Tuning Gamo CFR build / tune

[270windude]

I decided to make some videos here... clearly I have spend zero effort at production as I’m not trying to do anything but contribute my hobby. I’ve spent even less effort on editing. 

The is a video of me doing some touch up work to the glass bedding of my CFR. I was planning on drilling out the holes for the stock screws and doing a real pillar bedding but they seemed loose enough from the factory to where it’s already essentially pillar bedded. It’s not perfect yet. I still need to do a lot of work and finish ensuring that I have the entire tube free floated except the rear block and the forend. I’ll just use this thread to detail my trials and tribulations with this particular gun. I have 3 other projects that will be getting some attention once I have everything I want done with this one. 

https://m.youtube.com/watch?v=YqGIpAiAvG8&t=13s

 

[270windude]

Here’s the accuracy from the day after doing the touch up on bedding. Today actually. I managed to get 4 shots under a dime at 43 yards with a little flier but they were also unsorted pellets. The 4.53 Exacts did quite well too so I’ll keep tuning for those as well. 

https://m.youtube.com/watch?v=lhgroKMEjAs

 

[Odoyle]

So do all Gamo springers require such effort to make them shoot decently? 

 

[270windude]

I honestly don’t really know. I can’t help but tinker.

The underlever guns seem to be accurate out the box. Out of the 3 I’ve had though I will say I would never at all expect half inch at 43 yards nor under .2 at 35 from a stock Gamo anything non PCP. If someone claimed that they were getting that I’d assume it was a lie. On another forum a member is telling me he has a standard gamo break barrel and is shooting .5 to 1 inch groups at 50 yards. I DO NOT believe that. If I struggle at 50 I have no idea how someone else could pull it off unless I see it on video. It really just depends on how lucky you are with pellet choice for a new shooter.

I’ve significantly tamed the recoil in the CFR, weighted and stiffened the stock, new trigger, specialty bedding, all new internals, etc. most of this is for shot cycle and just to have something that’s custom. All the little changes certainly helped accuracy though. When I played with spring load vs piston weight I noticed changes in accuracy as well. I’ve gone though several pellets that tested as the CFRs favorite since I’ve started. 

As far as break barrels my experience is limited to the Hunter series. They’re not bad but some pellets are literally 4 inch groups at 20 yards or even less. I can see how someone could pick up a Hunter Varmint and shoot a 5 inch group at 20-25 yards (specifically of my older gamo or Crosman pellets) and give up on it. With the break barrels I mostly like to tune them for shot cycle. I do the basics. Tighten spring guide, install a piston sleeve that will vary in thickness and coverage depending on what velocity/ smoothness-of-recoil trade off I want. If you get the right pellet off the bat it’s not surprising to have one that shoots half inch at 20 yards right off the bat with like several pellets all touching and a flier about half inch away every 3-8 pellets depending. At distances past 20 yards I haven’t had luck with untuned guns. I haven’t tried much either though just enough to determine my breakbarrels are best at sub 30 yards for small game hunting or plinking. Today I took my Gamo Hunter Varmint out to the mountains all day. It’s received the mildest tunes I do as standard and with Crosman brown box 10.5 I was shooting 10 shot groups under or at a dime off hand at about 20 yards. I tried several other cheaper pellets I desperately hoped would work, to include the hollow points and didn’t have any accuracy. I’d say on average with cheap pellets it’s a 4 inch 20 yard gun with the extreme being like 5.5 inch flier groups. The CP 10.5s were spot on though. 

Overall I’ve found gamo barrels to be a happy medium between top quality piston gun barrels and piss poor barrels. I’ve had other guns that I can’t ever shoot accurately and others that shoot everything consistently and some great. Gamos have always shot well enough to keep my interest and fan boy status for the price. 

 

[KWK]

And you did it your way! You make great contributions. Thank you.

The RB2 rotary breech is really nice. No bear trap to snatch fingers. I wish they had used that on the Stutzen (as was used on the later BSA Airsporter Stutzens). The Stutzen's pop up breech is annoying to use. 

 

[xsarfc9x]

Good efforts man. I got an older tuned CFX and a BSA Polaris and enjoy then both. Ill post some groups to compare at next time I go shooting. 

@KWK you mean Gamo Stutzen with the pop up breech? I thought the BSA Stutzens only came in tap loader and RB2. 

 

[KWK]

Yes, "they" being Gamo. The subject of the OP. I find the pop up port to be fumbly. I have Gamo Stutzens and both type BSA Airsporter Stutzens. The Gamo Stutzen will never be your favorite shooter as manufactured. IMHO the best thing you can do is fit a milder spring so you don't need the cocking lever extension. Milder firing behavior too. Then install a gold aftermarket trigger. Works better and it's pretty. You'll have to live with the fumbly loading port.

The Gamo underlevers are known for very good accuracy potential. BSA Polaris is practically a CFX Royal with a better BSA trigger. Is the barrel from Birmingham? That would be good.

 

[xsarfc9x]

I didn't mind the pop up breech on the Gamo Stutzen but the RB2 would have been better. Ive had the 2 BSA Stutzen variations as well, but prefered the Gamo overall. Your probably right on detuning the Gamo version. I never got great accuracy out of the BSAs even after adjusting the barrel tension. I still have a Airsporter RB2 and a Superstar which I like alot and are tack drivers.



Polaris is basically a newer BSA Silverstar which Russ Best said was the most accurate spring gun he'd ever shot. Sadly it doesn't seem the Polaris lived up to its predecessor. Out of the box it was horrible and probably the twangyiest gun I've shot even with the heavy beech stock. 

I had a spare Rich in Mich tune kit i had it installed in it, swapped the BSA trigger unit for a standard Gamo trigger unit and a gold trigger in mine. Standard trigger unit didnt fit into the original stock so now its in a synth CFX stock now. Haven't dont alot of accuracy testing but it's better then before and consistent. Probably needs to settle in some more.



The Polaris uses BSA barrels but not many ppl reported good accuracy from them and there was a guy in NZ and a few others who found tooling marks at the end of the barrel and even after addressing it never got the expected accuracy. They have the recessed crown and maybe the Gamo techs messed it up. I believe it says made by Gamo for BSA on the barrel. I checked the barrel width and it wss 16mm barrel so it is a BSA . At the time I gladly paid $250 for my Polaris in hopes of getting a CFX with a match grade barrel but seems the execution was let down.