GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: Toolmaker on December 11, 2010, 06:11:48 PM
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I really like my Gamo Varmint Stalker but I like short rifles and I don't like the plastic muzzle brake. I chopped almost 6" off the barrel and re-crowned it. It's 12.5" long now. To finish it off I added a metal Crosman muzzle brake. I cleaned the barrel good with goo gone, put moly on all the pivots and reassembled. The rifle has a much better feel to it now and looks much better without the plastic muzzle brake, IMHO. I put about 60 - 70 rounds thru it this afternoon and it still shoots great. Here are a couple of before and a couple of after pics:
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Nice work.
Had a chance to check accuracy and muzzle velocity yet?
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Nice work.
Had a chance to check accuracy and muzzle velocity yet?
The accuracy is at least as good as it was before the chop, maybe better. I am far, far from being a great springer shooter so at this point I'd say it shoots better than I do. I don't (yet) have a chrony so no way to check muzzle velocity.
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That looks great. Nice work.
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Nice shooter I have a remmington summit chopper that I like howie chopped it and I bought it
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How u recrown?a barrel
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How u recrown?a barrel
What he said!
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How u recrown?a barrel
Here's how I do it:
1) I remove the barrel from the gun.
2) Cut it to the desired length with a band saw or hack saw.
3) Square the end. I use a milling machine / end mill for springer barrels. Crosman 13xx and 22xx barrels I put in a lathe.
4) This is the most important step: I put a chamfer / bevel (aka crown) on the end. The actual angle is not really important. What you want is for this to be the same size all the way around the bore (concentric). I've used a variety of methods for this. A round head or button head screw chucked up in a drill with some lapping compound works well. A pushrod from an old engine makes a good lapping tool too. I've found that using a tapered grinding stone in a die grinder / dremel first works good for getting the crown to size then lapping to get it smooth and burr free.
5) Clean the barrel real good.
6) I stick a cotton swab in the muzzle and pull it back out. Use a magnifying glass to see if any fibers are caught on the crown. If there are then there is still a burr that needs more lapping.
7) Use a little cold bluing compound to re-blue the chopped end.
8) Put it back together and shoot it to see how it performs!
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Is it signifigantly harder to cock with the shorter barrel?
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Is it signifigantly harder to cock with the shorter barrel?
I cut almost 6" off and I was afraid it would be but I really don't notice much difference. It might be a little harder to cock but it's not difficult. I don't think I'd want a magnum springer with a barrel that short though.
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I've thought about shortening my own barrel too, I guess to see how it is to cock it at the shorter length, I just hold it at that length and cock it. I'd love to see chrony numbers on this mod, I have a feeling that my barrel is too long and I might get more speed with a shorter barrel.
Crosman .22 Titan GP with 17" stock barrel.