General Discussion To Gateway To Airguns > Gamo Gate
Gamo Whisper tuning
Bob Fairchild:
Guys:
In answer to Jared's question about sideward torque at the tip of the barrel - yes I do get movement . I was not aware of that and am somewhat surprised at how much movement is there. I guess you have raised an interesting question for an expert, which I can assure you I am not.
Bob or Gene or another tuner or Gamo tech should be able to explain that phenomena to us. Sorry I didn't respond sooner. Stuff!
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Bob
airiscool:
"In answer to Jared's question about sideward torque at the tip of the barrel - yes I do get movement . I was not aware of that and am somewhat surprised at how much movement is there. I guess you have raised an interesting question for an expert, which I can assure you I am not. "
I did the same as Jared asked with my 22 Whisper and yes, there was movement, but no 'perceptable shake' to use an old tolerance term.
Then, the question is where is it moving?
To take my greasy-left-paw-holding-the-reciever out of the test, I clamped the reciever in padded vice jaws and got less deflection with the same moderate push-pull.
Then, to take any breach/reciever play out of the test, I clamped just at the breach and got just about the same amount of deflection.
To further test breach/reciever play, I measured the gap on either side of the rear most part of the breach in the reciever forks and got .007 inch on one side .009 on the other. I cut some .008 shim stock and put that on either side, repeted the reciever vice clamp deflection test and it was about the same as the first time.
Without using a standard force and measuring the amount of deflection each time, I think a major portion of the precieved movement is barrel deflection . The steel barrel is only 7/16 inch od inside the plastic. Not much meat for barrel ridgedity.
I have the gun apart now to install a gas spring and do a general inspection and de-burring. The real test of reciever/breach play will come when I get this thing back together and see what affect the .008 shims have on shot groups.
Paul.
DWM:
First off, sorry for the delay. I've been away from the computer for a few days. I love the wood stock! Really beautiful.
I also have a very slight shift in the front end of my in both directions. A little disconcerting! I wonder if other break barrels have the same issue, like a RWS 34. It must snap back into the same spot when shooting, otherwise you would have pellets all over the place.
I'm so impressed with this forum, like Paul's response to your barrel issue... measuring the variance to .007 inch! Anyway, thanks to you all for responding to my original question.
It's sunny and calm right now. Time to go shoot some paper.
Don
gamo2hammerli:
Welcome to the two members DWM and Bob Fairchild to the GTA forum and family. Just shoot the airgun a few hundred times...a 500 count tin of pellets at least to find out what she likes....and it'll settle down some and season the barrel. After that you may consider a home tune or pro tune depending on the situation of the gun. All my airguns have not been tuned in any way...except the Crosman Sierra Pro because I had to change the spring....since I had her opened up....I gave her a home tune.....and after 200 to 500 shots (Depending on which gun) everything settled down and they are pretty accurate out to 30 meters (average distance for an airgun). If there's a miss.....it's most likely me.
CO_AirGunner:
Interesting. I am hoping we get some more people checking this. My whisper now has about 2,000 shots on the clock. I've noticed some accuracy issues lately, more specifically, two distinct groupings from the same pellet. That's when I found that my barrel was shifting almost 3/16" either side of center. :o
I am told that the pivot is sleeved (in other words - the pivot bolt rides inside of a metal sleeve pressed into the synthetic material). That being the case, all I can figure is that the synthetic has worn out a bit from rubbing on the steel receiver forks during the cocking cycle. I'm not sure if shimming is the answer or tightening the pivot bolt.
All I know is that I should be seeing worse spreads at the target than I am, so maybe the barrel kind of self-centers during the firing cycle; I don't know. Doing the math, 3/16" of movement at the end of the barrel is about 3.75" at the target at 10 yards (which would be 7.5" spread between the two groups). Since I noticed this, I typically nudge the barrel to the right after cocking. If I nudge the barrel to the left instead, my groups move about 1.5" - 2" in that direction. It is frustrating. Unfortunately, my groups (when nudging the barrel in the same direction) have opened up a bit to about 3/4" 5-shot groups at 10 yards from less than 1/2".
I've been messaging with CDT about this, but I haven't heard back from him since my last message. I'm wondering if this issue is reserved to the synthetic barrel Gamos or if the all-metal ones have the same problem.
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