I need some help - Gamo Bone Collector accuracy

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flyawaydoug

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Sep 22, 2015
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Hi All,

I am a 62 year old grandfather of 4 and I have been away from shooting sports for about 30 years. I used a Benjamin .20 pump in the 70's to teach myself how to shoot right handed. I am a lefty, but my master eye is my right eye. My accurracy went from miserable to marksmanship award quality from that experience. We moved to Louisiana recently and bought a home. I counted over 20 squirrels in my back yard and knew I had to do something. I purchased a Gamo Bone Collector .177. My experience with this gun has been dissapointing to say the least. I have installed Charlie da Tuna's GRT4 trigger and mounted a BSA 3-9x40 AO scope. I have practiced the artillery hold. Even when shooting from a bench with a soft rest I struggle to get groups under 1" at 10 yds. Most groups have 1 or 2 fliers out sometimes as much as 2" or 3". I have tried 5 different pellets. I haven't remove the shroud (I'm not really sure how) but a close inspection of the bore hole does not show any markings.

In frustration, I ordered a .22 Disco. I had the scope zeroed in 4 shots. I consistently shoot 5 round single hole groups and 10 and 20 yards. I have taken 10 squirrels in 11 shots. All but one were well placed head shots. So, I don't think it's me but I could be wrong. Any help would be appreciated.
 
Oh man, you did right ordering the Disco!

"Cheap" springers, especially higher powered ones can be a real pain to get right, if at all.

As for the springer, how many total shots so far?

It often/usually takes several hundred pellets to get lubes settled/burned out, and things smoothed in. Besides that, ensure stock screws stay tight, ensure your scope is staying put (and not damaged from the recoil!), and just shoot. After a tin or two of pellets, try some paper again. Then try several types of quality domes, If all fail, IMO, sell it and cut your losses. 

 
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I have the same Gamo Bone Collector as you in .177. The most accurate pellet I found to be is the JSB Diabolo Exact Heavy in 10.34 gr. I knocked a tree rat off a branch at 90 yards with only a few shots. I had to get the holdover right.
So the accuracy is not that bad at all with the Gamo. Just make sure you add good glass because the vibration of the gas ram is tough on scopes.
 
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I have a Gamo Varmint Hunter in .177 and it shot the same as your bone collector. Binfordw is correct. They shoot too hard to sbe accurate. The manufacturers build them to be more "powerful" to attract buyers. Most people assume more is better. I built myself a spring compressor and "detuned" my rifle. I cut 3 coils off the spring and cleaned then re-greased it. It now shoots at 950 fps and I get .105 one hole groups at 10 yds. With less recoil your accuracy will increase. I shoot Air Arms 8 gr, AA 10.3 and Predator Poly mags. All shoot great. JSB in the same weight pellets as the AA shoot identically.With my limited knowledge I would recommend in a springer to not get one that shoots over 1000 fps or perhaps a 1200 fps. They all regularly shoot less than advertised. I also have a .177 Discovery that can shoot under 1" at 50 yds from a bench with no wind. I have shot a couple of 3/4" groups when everything was just right. 
 
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My gratitude to all for responding. I will put another couple of hundred rounds through the BC before doing anything drastic. I am particulary intrigued by unclebuk's mod. But, unfortunately the NGT spring piston is what it is. One thought that occurred to me is timing. Specifically does the pellet leave the barrel before the piston reaches the end of it's travel. I suspect that it doesn't. Most of the recoil comes at the end of the movement. I wounder if shortening the barrel would help. Just a thought. 
 
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I'm no expert, but there should be some online animated gif's that depict a springers firing habits. Basically EVERYTHING that causes recoil and movement happen while the pellet is still stationary- and/or in the barrel. This is what makes harsh firing ones so tricky to shoot well. I would not bother with barrel length in my opinion.


Ah, here are some good ones

http://www.arld1.com/pistonpelletdynamics.html


http://www.arld1.com/rifledynamicssmaller.html
 
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The BC does not have a spring. It is a gas ram unit. The rifle is very hold sensitive because it is light and has a long second stage trigger. Try pellets over 10 grains for accuracy. If the groups don't get any tighter, shortening the barrel will probably not get it done either. Good luck. I have had my BC for two years now and it is still holding up fine.
 
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