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fell off

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xyon View Drop Down
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    Posted: 22 Jun 2017 at 4:26pm
I got round to reassembling the Gamo hunter I have been restoring. I had noticed that the previous owner has epoxied the scope rail on to the compression tube. It was hard to miss the globs of epoxy on the sides of the tube, which I cleaned up, but as it looked secure I left it alone.
After about 5 test shots the bloody thing fell off Angry

Question is how to repair it?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 6:42pm
Does the gun have dovetails cut into it? Can't quite see. Otherwise looks like there were bolts probably tapped into the action that have sheared off. You would have to remove those from both rail and action and if the threads are still ok, you could simply replace them and use some loctite. Your biggest thing would be to watch, will be the other end of the screw/bolt extending into the compression tube, as they may obstruct the piston or spring as they move.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 8:22pm
the newer gamos have dovetails cut into the tube. But not this one. The rail has circular bumps on the bottom that are pressed down from the top. These fit into the holes in the tube. Then they must have been expanded/riveted (or possibly spot welded) from the inside, I presume using the cocking slot for access.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pauly5 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 9:27pm
Interesting. What about countersinking a screw from inside and bolting down the scope trail if it clears all the internals.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nunga Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2017 at 10:09pm
that rail is not mounted on the compression tube its self by the looks so it shouldnt be that hard to fix. its on the spring retaining part on the gun...the compression tube is located at the front of the rifle.

you should be able to drill the holes out and tap a new thread in the part of the gun without to many problems then bolt it to the gun. just make sure the screws are not to long. it looks pretty bad to look at...but shouldnt be too hard to fix  Thumbs Up


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Post Options Post Options   Thanks (0) Thanks(0)   Quote dvlnme Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2017 at 6:36pm
This used be real common prob with old mauser 98 rifles n others as well ,screws used sheer off if made 
 soft steel,fact is springer airguns lot harder on mounts than any firearm, due recoil being forward, 
 rather than reward as with firearms,and there being less depth metal to put screws into on the tube etc
 Fact is it can be harder to keep a scope on springer airgun than biggest magnum firearm,modern airgun
 rated scopes much stronger than equivelent firearms scopes,these days i only use good airgun scopes
 evan on my firearms,simply coz they tougher.
 I used to put cap screws threaded into tube,then drill two holes in mount for cap screw heads as anchors
 then screw mout down as normal,never had one shoot loose,
 Cheers Mike 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 25 Jun 2017 at 9:55pm
I've drilled out the rail and tube with a 5mm bit and tapped the rail with a 6mm thread. I'm trying to decide how to secure the bolt to the tube. The tube is 1.7mm thick. As nunga says its behind the compression area, so a super smooth finish is not required, but the back of the piston rides over this area so can't really have anything protruding.

I was thinking about drilling the tube to 6mm, and turning a bolt down to have a tiny head tapering from 6.0 to 6.3mm. Maybe file the tube to have an approx matching taper.

Other idea I had was more of a quick and dirty. Tap the tube too (with the rail clamped to it) Peen a grub screw to expand the end and squash the thread. Then screw in from tube side. When expanded end of screw binds on tube it should pull the rail snug and be difficult to undo, so hopefully won't come lose.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nunga Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jun 2017 at 2:31pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jun 2017 at 5:19pm
I'm not sure how I could use a cap screw and have it be flush with the inside of the tube, or did you mean for the head to be countersunk into the rail and have the bottom of the screw flush with the inside of the tube?


Edited by xyon - 26 Jun 2017 at 5:19pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nunga Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jun 2017 at 5:38pm
yep countersink the head into the rail and cut down the screw to suit.
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