GTA
Gateway To Product Reviews => Air Gun Mods and Tunes => : Rixtrix April 11, 2007, 03:53:21 PM
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Continuing with my thread from The Shop, I think I found what may be the problem with "Twang" and vibration after installing the spring and lube. I used polyolefin shrink tube to try and tighten up the guide to spring clearance, but it acted the same as before the spring broke. Brought some measuring tools home from work to check the clearances:
New spring ID-.533"
Tophat OD-before: .500"
-after: .522"
Guide OD -before: .483"
-after .509"
Only problem I see is that there is still way too much clearance between the guide and spring. The problem might be solved by putting on another layer of shrink tube, but then the plastic sleeve the spring sits on probably won't go onto the guide: Sleeve ID-.517, Guide OD under sleeve-.510. If I reamed the sleeve to fit over the shrink tube layers, then it would be too loose on the guide, unless I put the second layer all the way down the guide. Gonna talk to CDT on this tomorrow AM
Ric G :o
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Put a double layer of shrink tube on the rear guide and it miked out the same as the spring ID. Didn't ream the plastic spring stop, just added another layer of shrink tube over the first. CDT said it may break if I reamed it. Pushed it into the spring and assembled the gun. No more twang! Didn't have time to go get it chronyed or check it for accuracy.
Besides, the winds blowing an unusual 30 mph.
Ric G :D :D :D
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According to CDT, A stock Gamo spring is .520-.525"ID. The one I put in was .533". Don't know what it was out of as I got it used from Rich. The stock, broken, spring measures .521" as does the other spring I got from Rich in Mich.. The one I used seems to work OK as the chrony showed it shots about what a Shadow should(855 fps with CPL's), so I'll leave it in until....... Sure is a lot smoother and quieter now. Only about 50 pellets through it, but hope to do a lot more this afternoon.
Ric G