by B.B. Pelletier
Photos and test by Earl “Mac” McDonald
Gamo CFR underlever air rifle.
One of our readers asked if we would test the Gamo Whisper CFR underlever air rifle, and I asked Mac to do it for you. That was a couple months ago when I was unable to cock a spring gun. In the meantime, I’ve grown stronger and now I’m able to cock most springers that are easier to cock, so I’ve started testing the BSA Polaris, which is another underlever that has the strong look of its Gamo heritage. However, these two rifles are not different versions of the same airgun. Despite their similarities, there are significant differences between them.
The Whisper CFR is an underlever spring-piston air rifle. It’s currently available only in .177 caliber. It has a synthetic stock with an open thumbhole pattern and an adjustable cheekpiece. Although it comes with fiberoptic open sights, front and rear, it also comes with a 4×32 scope and rings.
The cheekpiece is adjustable for good eye relief when using a scope.
Mac commented that the fiberoptic sights are smaller and sharper than others he has tested. They also adjust with crisp clicks. he was unimpressed by the scope that comes with the rifle, but we’ll learn more about that in the accuracy report.
Gamo advertises the rifle as capable of 1,100 f.p.s. with non-lead PBA pellets, so I would imagine the velocity with lightweight lead pellets will be in the 900 f.p.s. range. The rifle features the same rotary breech that’s also found on the Polaris, which makes this a safer rifle to load than guns with sliding compression chambers.
The rotary breech works like the breech on the BSA Polaris. The piston must be withdrawn before the breech will open.
Once open, the breech provides a groove to guide the pellet into the end of the barrel.
The rifle is large, at 46.85″ long, but relatively lightweight, at 8 lbs. even. It feels lighter. The stock is synthetic, with rubber panels that serve the same function as checkering. The length-of-pull is a long 15 inches.
The cheekpiece is adjustable with about an inch of travel. Mac found it could be tipped forward and back, though he doubts that was part of the original design.
Being a Whisper, the rifle has a baffled muzzlebrake built right on the end of the muzzle. It reduces the sound of the report that comes from the muzzle, although shooters will still hear the powerplant noises through the bones in their cheek.
Mac also felt the arc of the underlever was too large to be dealt with easily. I’d reported that the Polaris cocks easily, and both rifles have the same amount of travel for the lever. The difference is in the effort required to cock the rifle. I measured the Polaris at just 26 lbs. maximum effort, while Mac measured the CFR at 40 lbs. That 14-lb. difference apparently makes all the difference in the world.
Just like the Polaris, the CFR underlever comes way back, but it takes considerably more force!
It’s interesting to see Mac’s reaction to this new rifle, because I’ve been associated with it for many years, except for the Whisper addition. Mac is showing me many things I never saw when I reviewed it, plus he’s proven that it’s not just a rehash of the Polaris or of the older Gamo CFX.
Morning B.B.,
Glad to hear that your strength is coming back and that you’re feeling better! A 15″ length of pull seems great for me, being a slim 6″2″ , but seems like a lot for most folks. Can it be shortened some how?
Bruce
B.B.
Glad to hear that you are getting stronger by the day. Can you say or show where the transfer port is located in that rotary breech design??
Thanks
Pete
Pete,
The rotary breech itself is the transfer port. When you rotate it closed, the port is aligned with the rear of the barrel. The piston actually touches the rear of the rotary breech.
B.B.
Hi All,
was leafing through this month’s Rifleman magazine (National Rifle Association’s publication) and happened to look at the article on page 66. For those of you who don’t get or can’t get this publication, it’s a picture of a Marine sniper in Vietnam sighting with a Winchester Model 70 bolt action with a 8x Unertl scope. What I find most interesting, however, is the position he’s in. Left arm across his knee, rifle resting on the crux of the elbow, the air rifle Field Target competition position most recommended today. Probably not news to many but it is to me.
Fred PRoNJ
Fred,
When I was in the 3rd Cav., we had a model 70 sniper rifle in our arms room. It was always in a hard case and not issued to anyone. It was not part of our TOE, but for some reason we had it.
B.B.
So why did the military switch from the Winchester 70 to the Remington 700? That cost Winchester a pretty penny I do believe. I’m starting to believe the issue was not performance but convenience. There is some discussion that the push-feed is more accurate than the controlled round feed like the Winchester 70 model because the bolt head is more enclosed. But David Tubb used the Winchester 70 action before switching to his own gun, and the FNH SPR built on the Winchester 70 and used by FBI HRT is as accurate as anything else.
Matt61
Off topic. I’ve been very busy ,but I just saw the posts by Matt 61 and Kids Again in regards to the Savage rifles from the weekend and yesterday, on both the bolt action 110 and lever action 99. I handloaded a lot for a 99 in .243 cal and can tell you from much experience that you will need small base dies to reload for it. You will have chambering problems with your reloads in that caliber if you don’t. Also case life is limited compared to a bolt action, and trim to length is important with that one. It’s a easy carrying and good rifle. I shot more woodchucks with it than with any other rifle I’ve used , except another Savage which was in .22 hornet. That was because you weren’t tempted to mount a set of wheels on it,to lug it around the hills,like some varmit rifles need. The 99’s barrel is not installed like the ones on the bolt action 110. On the 110, the barrel is finished chambered and screwed into the receiver with the bolt in place ,then a minimum headspace gauge is placed in the receiver the bolt closed and the barrel collar tightened . The Savage 110 is also accurate because the receiver is not cut down as far on the right side , there is more metal left in it’s tubular receiver than in others. Because of this it is stiffer, but it comes with a price in my opinion. It is harder to feed cartridges into the receiver opening than say, on a 98 Mauser style rifle. The scout rifle idea in the Savage 110 model is most inferior to a Mauser 98 because of this. The 99 is a faster to load rifle than a 110 , and is the best lever action scout rifle.The barrel on the 99 is just treaded into the receiver in the usual way. I’ve shot a few 99’s and still own one in .250-3000 . That was the cartridge that was necked down to make what we now refer to as the .22-250. If you are looking for used $200 varmit rifles, try a Savage 340 series. That one is like the bumble bee anology . You would never believe to look at it , but it is more accurate than a lot of fancy stuff that is supposed to be. Sorrry for the off-topic rambling , but I’ve had more than a passing interest in Savage rifles and shotguns , and have messed with a few. Robert.
Robert,
I have a question for you. That Savage .22 Hornet you mentioned. Was the bore .223″ or .224″? I’m reloading for a Savage .22 Hornet that’s a model 23D. That’s the one in which the barrel is made integral with the receiver. It’s got a .223″ bore and I’m trying out some .223″ Speer bullets, to se if they are more accurate. The larger bullets do work without signs of excessive pressure (factory loads), but since the smaller bullets are available I figured I’d try them.
A couple years ago I had a Stevens 225, which is the same as a Savage 340 in .22 Hornet, but I only shot it with factory loads and it was mediocre.
B.B.
BB: it had the .224 bore , it was the 340 series type, a 322 , (if I remember correctly as I no longer have it),not the 23 which I’m very familar with as I do have the 23 in .22RF,. 25-20, and 32-20. It was supposedly a surplus item that were once issued to pilots in WW2 and it had the butter knife bolt handle, but was otherwise stock 322,325-340 series type. My old man bought it from Kleins of Chicago back in the 1950’s. The book “Hunting With The .22” C.S. Landis, and “Twenty -Two Caliber Varmint Rifles” by the same author, have a lot of information on your gun, and loading for it. The first was a Samworth book(latter Stackpole) and the latter a Wolfe publication, ISBN 0-935632-97-2(1991). If you don’t have them, tell Edith you need an early Easter present, they are invaluable references, and good reads.A word of caution on the 23 is in order though. They can develope headspace issues. According to Frank De Haas’s writings on gunsmithing them ,it can be remedied easily. That is done by making a shim washer and placing it between the boltsleeve and bolt body. This is a perfect fix as you noted, the barrel and receiver is one peice. Take care ,Robert.
The ones I have shot were both in 30-30. One was a Stevens and the other a Savage. Both were scoped and would shoot one inch 100 yard groups using Remington 170 gr factory ammo.
Mike
Robert, I agree with you about the Savage 340 series. Another is the Remington 788 series. With those, be careful with the bolt stop, it’s just a small pin and and can shear if the bolt is worked with force over a period of time.
BB has one in 30-30, hows it working out?
Mike
Mike,
I haven’t shot the 788 since getting sick last March. It’s another gun I need to get back in action.
B.B.
BB,
Is the 788 the rifle you are using for your ’30-30 the most accurate cartridge’ project?
ka
KA,
Yes, it is. Though with the Ballard now on board I see that the .30-30 has a lot of catching up to do.
B.B.
Ahh, I just saw this response… nice!
ka
You own a Remington 788?! I’m jealous.
Matt61
Rob’t from Arcane,
I plan to reload for the Savage 10 in .243. The Savage 99 in .243 is a deal I won’t pass on and was wondering if and how I would load for it, thanks. Small based dies??? Not to take up bandwidth on this site… my email address is dan@dswhite.com and I would like more info if you could contact me.
Matt, your reference to Tarzan and the apes is priceless!
ka
Small Base Dies, they are made for improved chambering of reloads in pump, lever, and semi-auto rifles. They more fully re-size the case head. Other companies may have them but RCBS are the ones I have seen and used.
Mike
Mike; that’s the brand I used too , and I had regular dies that I used first which is how I discovered the issue with that gun. You are very right on the 788 also, as I have one in .222 and it is very good. Faster lock time than most and smoother than the Savage 340 I still have in .222 as well. Two hundered dollar rifles ,you gotta love them ,(and another secret of gun buying/ trading)! Robert.
Mike,
My dies are RCBS, but not small base specific? Gonna have to look into my RCBS catalog. With small base dies will I need to pay closer attention to trim length?
ka
KA: As long as BB doesn’t mind ,I will have to waste the bandwidth ,as E-mails are hit and mostly miss with me. (BB or Edith: Feel free to delete this if it’s too off-topic,no hard feelings) In my experience you will need the small base dies for the 99 lever, and you will need to keep your reloads specific for both rifles. I used mostly 75 gr HP and 80gr SP in the 99, Speer and Hornady brand . I also used IMR3031 powder as I had a lot of it back when I reloaded for that gun. There are probably better powders for it ,especially now. The few 100gr. jacketed bullet loads ,factory or handloaded, I used, did not shoot as well in that 99’s barrel. I also shot cast bullets in it,using Red Dot shotgun powder,cast from a Lyman mould.It was a Lyman #245496 , a Loverin style ,gas-checked ,hard cast bullet of about 80grs. The cast bullet loads were OK ,but the long hard bullets ricochet badly, and the grease grooves are exposed in the .243 cartridge because of it’s short neck. This meant that they were prone to picking up crap ,and had to be carried in a leather or plastic case with a lid. My take on the 99 as to caliber selection is this, as far as the ones I’ve used. IMO,a 99 is best in the original .250-3000, and .300 Savage. It’s handy ,but not spectacular in .243 and .308. The .243 and the .308 have it all over the other two calibers though ,in ammo availability and power. But, note that the .300 is almost as powerful ,practically speaking as the .308 ( was actually the inspiration for the 7.62), but I personally found .250-3000 more useful for my needs than the .243, in both handloading for it, and shooting it . That is why I only kept the .250-3000. However ,if I was you ,I certainly would not pass up any 99 for under $300.You would not lose on it.Regards ,Robert.
Robert From Arcade, BB, Edith,
Yeah, I was concerned with my “off topicness” lately and the few here that get bothered with non airgun discussions. I would have NO PROBLEM at all if this topic got ‘bumped’ or deleted here, either.
That said, here goes… I value your input on the subject and am saving to file. I won’t be loading .243 right away, as I’m starting with .45auto this weekend. (finally bought bullets). I’m not sure If I will even be shooting it much, as it’s one of those purchases that BB mentions in his “the art of collecting airguns” post, it’s not an item I need or was looking for, but rather an item I was aware of and looks like it has more value than the price tag it was wearing. Who knows, I might trade it for a Ballard some day! Though if I find another 99 in 250-3000, or .358winchester I’m buyin’ it as well! Already have one in .300 Savage and like you said that’s close enough to .308 for me.
Anyway… I have learned from this that there is specific loading requirements for bolt action vs. lever/auto actions. Makes sense. Did you try lighter bullets than 80gr? Is the twist not enough for the heavier bullets?
ka
No, every thing in regards to trim to length stay the same.
Mike
BB,
The CFR looks like a nice one, though I’m not sold on it’s price range. The stock looks pretty gimmicky and for the price it should be laminate wood, IMO. It’ll be nice to see how it does in the upcoming posts.
ka
KidAgain,
I’m not convinced that the stock is purely gimmicky. The adjustable cheek piece might come in handy for those who prefer high scope mounts. Just a thought.
Victor
And, the thumb-hole stock might help with trigger control. That would be a very nice feature, if it worked.
How does this compare to the new Gamo Whisper IGT that has just arrived?
Dave,
I just ordered a Gamo Silent Stalker Whisper with IGT for Tom to test. In fact, I just ordered a whole bunch of guns for testing:
Dragon Claw with dual reservoirs
Air Arms Pro-Sport (.177)
BSA Comet (.177)
Crosman Outdoorsman 2250XE (.22)
Ruger LGR Co2 rifle (.177)
Edith
B.B. –
Good to hear that you are getting stronger. I hope to read that you are testing more and more of the airguns yourself. After reading your post this morning, I clicked on the image of the CFR at the top of the article and checked out the additional images on the P.A. website. What is the projection on the underside of the stock, just in front of the trigger guard?
Regards,
– Jim in KS
Jim, if it is anything like the synthetic stock on my Whisper Camo .22, it’s just a small swell to rest the gun on your opened palm/hand (artllery hold, etc) Makes it easy to find the balance point each time.
Jim,
Do you mean that thing that looks like the safety on a Garand? It’s cast into the triggerguard and serves no function of which I am aware.
B.B.
How much longevity should one expect to get out of a gas ram as opposed to a metal spring? For example, the Crosman Nitro Piston. Should it be expected to have 10x the longevity of a traditional coiled spring? 20x? Is there maintenance to perform that will make it last longer? What about replacement upon failure? Can that be done by someone with tools and ambition, or does it HAVE to be done by a gunsmith?
What does the future of the gas ram look like? Is it going to have a long life in the airgun industry, or do you see it as a nifty gimmick that came and went? As I read reviews of guns that include a gas ram, I haven’t seen any down sides, so I am curious why they aren’t being included in more guns. Is it purely for cost alone? The Crosman Titan seems to run a pretty low price point.
jmdavis,
I have a gas spring that’s 13 years old and it’s still functioning fine. But I guess with the power that they are getting from those guns that have them, a steel spring will develop a cant in a couple of years. Plus, you can’t leave a steel spring cocked for weeks without some power loss/canting.
When the gas spring wears out, you replace it. They can be made to be repairable, but there are no repair stations set up that I know about.
B.B.
jmdavis984,
I have a Gamo CFX that I had considered modifying by changing from spring piston to Nitro Piston. I contacted Gamo about that, and they referred me to someone that they recommend for gunsmithing. I spoke with this gentlemen about what I wanted to do. He was emphatic about NOT recommending gas pistons, and would never do it. He said that they will tear your gun apart. Mind you, this is the ONLY person that Gamo recommends. For what it’s worth.
Victor
Victor,
Gas spring won’t “tear a gun apart.” That expert is sowing discord.
B.B.
B.B.,
Yeah, that’s what it sounds like. I love my Titan! It’s smooth and accurate.
Victor
Victor I have a CFX in .177. I sent it to PA a little over a year ago for the gas piston modification. I have run about 1000 pellets through it since then and have had no problems. The gun was already a smooth shooter and the gas piston just added to its accuracy. Mine is not being torn apart. Toby
Toby T,
Well, there you have it. It might be worth it to make this modification. Mine is very smooth and so easy to shoot well. Hopefully this CFR will be even better. My hopes are that the thumb-hole stock will provide for better trigger control, and that the adjustable cheek piece will allow for a better fit when using high scope mounts. Can’t wait for the next set of reports.
Thanks,
Victor
Victor, Do you have a Charlie da tuna trigger on your CFX ? I put one on mine and although it is much better than the original, I can’t get a decent feeling first stage out of it. Toby
Toby T.,
Yes I do. Unfortunately, one of the adjustment screws came loose and almost fell out. I need to use something like loctite to keep it from doing that. So at this point, I need to go back to the manual and readjust it, otherwise, it’s hard to say how it feels (or should feel). Mine is not well adjusted (like me).
Victor
Victor, I had the same problem with mine, the screws would move. A dab of blue loctite cured that problem. Then I went back to square one and put the screws in there original position. The second stage is right on but the first stage is inconsistent. Sometimes loose and other times creepy. I have gone to Charlie’s website and tried to get it adjusted right using the instructions found there but no luck. Please let me know how yours comes out after you fix it. Thanks! Toby
Their not there.
Oh, I have a Crosman Titan with Nitron Piston that I absolutely love.
Well, I see spring is here. The red squirrels have invaded the bird feeder. One Sunday and another just now. So, the Diana 52 in .177 gets a workout. No survivors.
Mike
Most of what I have read is that a baffled muzzle brakes are not effective on springers. I thought that until I got an old style BSA Supersport Lightning which came with a permanently attached baffled brake. From a shooter’s point of view, I would agree that the baffled muzzle brake makes little or no difference in perceived noise level. But, I have found that the noise level off to the side or downrange is noticeably decreased. This makes for a more neighbor friendly airgun and may help not to spook game. You can’t always believe what you read.
David Enoch
This one looks promising. The CFX cut a memorable swath, and as I recall the Whisper received a very favorable review. Some combination of those designs would be good. B.B., I’m feeling very challenged by your most difficult to cock springers. I’m reminded of this exhibit at a museum in Minnesota where you pushed on a plate and measured your power against farm horses. I didn’t do badly…
Wulfraed, thanks for your info about headspacing. I seem to recall now that headspacing is measured from the case head to mid-shoulder or thereabouts. The information about soft-seating of bullets had to do with jumping the throat to the rifling. Thanks for the clarification. I’m still concerned about headspacing because apparently if you don’t get it right, your brass will wear out faster and you can even risk damage to the gun or injury to yourself. But I suppose that if I work within the 1/100 inch tolerances listed for case length in my manual, I should be okay.
Victor, what do you think about psychological rhythm while shooting a string of targets in competition? I noticed the other day, which was a good one for me, that if you start well in a group of 10, you sort of fall into a groove. It’s easier for the mind to follow the successful process than to screw up. It’s not unlike running a long distance race where you start hard, settle for the middle, and then apply yourself for the end (in shooting engaging the anxiety of messing up your group). I’ve heard of elite shooters including David Tubb talk about getting into a rhythm. On the other hand, this does seem to work against the prime directive to focus on each shot individually.
You might want to look at a viral video about a boy fighting off a bully in Australia. One cannot help feeling gratified to see aggression checked although mostly the video is crude violence that should have been stopped by adults. But my attention was caught by a particular technique. After taking several licks unanswered, the victim suddenly reaches out and deflects a punch very naturally. No hard block or artificial technique. He just kills the momentum of the punch. I would have advised an earlier intercept and a more circular motion, but those are just nuances. That boy’s got talent. I’m reminded of this character from a Stephen Hunter novel who says approximately, “I was abused and bullied for years. My hygiene was not the best. But then, I began weightlifting and found that I had muscle tissue that responds spectacularly to resistance. I lifted millions of pounds of weights. I learned to fight, and discovered that I liked hurting people. I looked long and hard for a place that could use my talents and finally found it in the Mississippi State Department of Corrections….” This is taking advantage of some of the lurid stereotypes of the South but I couldn’t help laughing.
An F-15E has been lost in operations for the first time in history in Libya! However, I understand that it was mechanical failure, so it doesn’t really count. And the main thing is that both crewmembers were rescued. Those planes must be getting pretty old by now.
More on John Browning. After being rejected by Winchester, he goes to Remington only to have the top executive drop dead within moments of their appointment! So, he goes abroad and singlehandedly resurrects the moribund Fabrique Nationale company. I always wondered about the connection between John Browning of Ogden, Utah and FN of Liege, Belgium. One of Browning’s innovative semi-auto pistols, an FN 1900 in .32 caliber was the gun that started WWI with the assassination of Archduke Ferdinand. Whew, not the kind of thing I would want on my conscience.
Matt61
Matt61,
Psychological rhythm is very real. Think of it as sort of a carrier wave that your signal rides on top of. For me, when I was “in a rhythm”, I’d have a certain song playing in my head repeatedly. It was always a feel good song (not annoying). You might say that it was somewhat like a chant for meditation. It’s essentially a good positive state of mind in which there is a natural flow that is somewhat like riding on rails. The good feeling is the carrier wave, and the details of shooting are the signal being carried. The carrier wave isolates you from distractions. It’s a stress reliever. At least this is how I have experienced it, and I’ve performed my best under such a state.
The point you make about the guy who learned that he could fight is a good one. You see, some people are natural athlete’s, much more so than others. Training enhances their abilities, but they are capable (dangerous) without it. What real martial arts training is about is giving an individual a method for building up a skill set that is almost natural. It’s about drill, technique, and experience. My understanding is that Okinawan Karate was developed for military purposes, meaning that it had to be something that was accessible to almost anyone. For it to work, it could not be such that it required special physical attributes or abilities (like size, flexibility, strength, etc.).
Victor
For what it’s worth, don’t worry too much about head space. If you start with a trimmed case that is resized according to the directions that come with the dies, you won’t have an problems. This comes from forty years of hand loading experience. You won’t damage your gun. The only rifles that I have used (and still do) that tend to have a lot of spring in the action resulting in short case life is the British 303 rifles with rear locking lugs. These would be the SMLE, No. 4 Mark 1 & 2, No. 5 and the like.
Even with these you won’t damage them due to headspace if you follow the directions.
Mike
You probably know this Mike, but it’s interesting to note that the SMLE series of rifles had an interesting way to allow for battle field wear ,that resulted in excessive headspace. The bolt heads were removeable, and numbered . The British ordinance folks just swapped the bolt head out for the next higher number . They went from 1-4 I think…
B.B.,
I like the ergonomics of the CFR over something like the CFX and Polaris. My guess is (I hope) that the thumb-hole grip would provide better trigger control. Is the trigger on the CFR replaceable with the GRT III trigger, or is it the “new and improved” trigger than cannot be replaced? Also, I’m surprised that it takes more effort to cock than the CFX, as the CFX supposedly shooters 100 fps faster.
In any case, if it’s as accurate as the CFX and the trigger is good, or replaceable, then the CFR could be a winner. I’d certainly consider it.
Victor
There’s supposed to be a new replacement trigger blade for the newer Gamo trigger group — though it doesn’t qualify as a “drop-in”; one needs a spring compressor.
https://www.charliedatuna.com/GRT-4G.htm
Google GRT-4G trigger (if the link doesn’t make it through)
Wulfraed,
Thanks! I knew that CharlieDaTuna was going to provide something, but wasn’t sure what, or when. I also forgot (wasn’t sure) if it was Crosman or Gamo that changed their trigger.
Much appreciated!
Victor
I’d checked the site for trigger options when I first ordered the Hunter Extreme .22 (which was rapidly returned — a test cocking, not even to full cock, showed me I wasn’t up to spending an hour at a range with it… The extra 15-20lbs needed over my existing models was too much… I replaced the idea with a Condor — wearing myself out the day before with the “belly” pump was a bit preferable [the last 500PSI requires me to lock my hands against my lower abdomen and then squat to get the air to flow into the tank, otherwise I just seem to bounce up like a pogo stick])
Yes, the Hunter Extreme is a beast of a gun. I have to put myself in a certain mindset to not be bothered by the amount of effort required to cock it. More than the cocking effort, what I don’t like is the stock’s grip. It’s very wide (too wide). I’m thinking of taking a Dremel to mine so that it’s more easy to grip it the same way each time. Hopefully, I won’t weaken the stock so that it breaks while cocking it. 🙂
BB The user manual associated with this gun on the PA site looks to be the generic, Gamo break-barrel guide. It does show a trigger adjustment for 2nd stage travel, don’t know if that goes with this gun or not?
Anyway, probably not much help for the new shooter or those who don’t know about underlever operation?
BB,
Although I’ve come on board with synthetic stocks (to the extent of owning one and liking it for a hunting rifle), the TH is still not my cup of tea. No matter, this does look like an interesting product and the TH is pretty popular with the younger crowd. We’ll have to see which one wins the accuracy race — this or the Polaris. Somebody mentioned a laminated stock. That would be a nice product variation for Gamo– an FT style laminated stock with some attention paid to making sure that power level and accuracy are optimized for target shooting. I won’t hold my breath :).
Hi Guys, off topic looking for suggestions. Just installed a Vortek kit in my RWS 350 Pro Compact with Leapers 3-12x TS series. Much smoother cocking now, shot cycle feels great, shoots 835 fps. 10 to 12 pellets in a row will go into a 7/8″ ctc group at 35 yards (which I am quite pleased with) but then zero will suddenly shift 2″ low and slightly left. She’ll stay there for 12 to 15 rounds, then walk right back to the bullseye for another 10 or 12 shots. It exibited this behavior before the Vortek kit also, but would not group as tightly then. I have resisted the urge to fiddle with scope settings this time around, in an effort to see if this pattern would repeat itself, which it does. It literally returns to dead-nuts zero for the 10 or 12, then drops low…and repeats. Stock screws, muzzle brake, scope mount have been carefully tightened and loctited where appropriate. Barrel pivot is properly snug, and technique is artillery-style and consistent.
The gun was quite dry when I disassembled it, and I may have under-lubed it when installing the Vortek kit (I prefer minimal and clean to excessive and yucky but I may have gone too far) My only theory is that, since the spring is free to rotate within the piston and guide, that the gun’s vibration cycle may “phase” in and out as the spring completes a full rotation and contacts the internals slightly differently from shot to shot while doing so, which perhaps it’s doing over the course of 10 to 15 shots. If this gun could only “stay put” when it’s grouping well, we’d have true love because I love holding it, shooting it, and looking at it! Help?
Ken,
I think there is something weak in the scope — don’t waste too much time until you try either open sights (if possible) or another scope. I had a scope on my .30-06 that would be dead on the first shot over several times shooting, but the second or third shot would be further away, and it was downhill from there — went from 1″ or better groups to 8 inches at 100 yards or something crazy like that. Because it was always dead on, I thought the problem was elsewhere (other than the scope) and drove myself crazy trying things. Finally, I just put on a spare scope and the groups were back, better than ever (probably all the things I did to “fix” the problem did a little bit of good :)).
Thanks for the reply, BG. I’ll try another scope, and also try putting this scope on another gun to check for consistency. I can say this scope is at least always very responsive to adjustments. Wierd thing is that this pattern I’ve observed is amazingly consistent. I’ve put 400 rounds through the gun over the last 6 days without a scope adjustment, and the pattern cycles like clockwork; 10 to 15 shots within a very tight group, followed by 10 to 15 shots in another very tight group, in a single different location. Then, it goes right back to bullseye for 10 to 15, then directly back to the spot 2″ low and 1/2″ left. I can fire 50 or 60 shots and end up with two distinct 1″ groups, and it never shoots only 1 or 2 or 3 in one group before shifting – always 10 to 15, in other words, it doesn’t jump back and forth – it’s always nearly the same number per “cycle”. I can’t help feeling like these guns would be more consistent if the spring were kept from rotating inside the gun and contacting the innards slightly differently as it does. I see this as a variable that should be eliminated. Just a “sixth sense” feeling I guess. I’m gonna follow your suggestion BG, and I’ll report back to you. Thanks!
Ken,
I does sound as though the scope is adjusted too high. You are describing the classic “scope shift” that results from this.
The solution is to install a drooper base so the scope can be adjusted down in the center of its range or lower. That will ensure adequate spring tension on the erector tube.
B.B.
Ken,
Your theory is interesting, but I would be a little skeptical about it given that the pattern has exhibited itself both before and after installing the vortek kit. So, you’ve seen it now across two different springs. The ability of the spring to rotate freely is needed to reduce torque that causes the gun to twist as the piston slams forward. From that perspective, I tend to view it as a good thing 🙂
I would be interested in whether a different scope changes the pattern or not also. Scopes affect firing cycles in odd ways sometimes if for no other reason than they change the center of gravity of the gun slightly. This effect tends to be more noticeable on magnum springers when using large scopes. I have just recently decided to forego a scope on my Ruger Airhawk because it’s so much less sensitive to hold when shooting iron sights. It may not be the case here, but it is something to consider.
One other thing you might try is having a buddy perform the shooting test and see if the pattern repeats when they are on the trigger. It would probably be good not to mention to them the pattern that you see when firing the gun just to keep the experiment as objective as possible.
Best of luck!
Thanks Bobby, gonna try another scope asap as you, B.B. and BG Farmer have suggested. I called a friend to borrow one last night. I do see what you’re saying about the need for the spring to rotate, but I wonder, if one end of the spring were secured and the other end were free to rotate, the shot-to-shot vibration cycle might be made the same each time while allowing the freedom of movement you speak of(?) I do want to stress that after the Vortek kit, when it’s “on pattern” this gun is shooting 10 to 12 shots within as little as 3/4″ ctc at 35 yards, which I’m happy about and consider to be excellent for any magnum springer. It’s murder on crows, pun intended haha.
Ken,
The theory about the spring is still an interesting one. And, your suggested test (nailing down one end) might be a good way to test the hypothesis. It wouldn’t be too difficult to go back to the original spring and simply remove the washers at one end or the other. Theoretically that would give a greater purchase to that end of the spring and slow or prevent the spring from precessing. Although, this might result in damage to either the spring guide and top hat depending upon their materials.
I am still skeptical though, because you have seen this scenario enacted over two different springs. Presumably, they would precess internally at different rates giving different results. That doesn’t seem to be the case from your experiments to date.
I would like to propose an alternate way to test your hypothesis. Since gas rams don’t exhibit the torque that mechanical springs do because of their design, were you to replace your spring with a gas ram, then you could truly test to see if a precessing spring were causing different harmonics as it rotated around from shot to shot.
Regardless of which approach you take, I would love to read about results that you get from each perturbation. Guest post! 🙂
Oops, I may have spoken too soon as there doesn’t appear to be an gas springs for the Diana rifles b/c of the piston and trigger design.
Thank you B.B. I have the RWS 1-piece mount with compensation. The scope never needed to be adjusted far from its out-of-the-box settings. Just now I turned the elevation knob “up” from current setting and stopped at 100 clicks before returning it and there was more to go, so it doesn’t appear to be near the limit. Your idea is something I had not thought of though. I’m going to try what BG suggested and swap out scopes for a while. Glad to hear your health is improving and that you are able to cock the springers!
When is part 4 of the RWS 350 coming?
EJBahnsen,
We got Mac a better scope for the fourth report, but I think I jumped the gun and had him return the gun to Pyramyd AIR.
He will check his gun safe this weekend, but he thinks it was returned.
I re-read the end of Part 3 and I did say we would run another accuracy test with the rifle. That was why we sent him the better scope.
I’m sorry, but I screwed this one up.
B.B.