fell off

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   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 

Question is how to repair it?

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xyon Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 20 Dec 2016 Location: Canterbury Status: Offline Posts: 135	Post Options Post Reply Quote xyon Report Post Thanks(0) Quote Reply Topic: fell off 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 Question is how to repair it?
	--- My favourites springer - Diana 52 PCP - FX Wildcat III

Pauly5 Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1410	Post Options Post Reply Quote Pauly5 Report Post Thanks(0) Quote Reply 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.

xyon Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 20 Dec 2016 Location: Canterbury Status: Offline Posts: 135	Post Options Post Reply Quote xyon Report Post Thanks(0) Quote Reply 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.
	--- My favourites springer - Diana 52 PCP - FX Wildcat III

Pauly5 Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Moderator Joined: 10 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1410	Post Options Post Reply Quote Pauly5 Report Post Thanks(0) Quote Reply 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.

nunga Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Forum Moderator Joined: 08 Mar 2013 Location: Pukekohe Status: Offline Posts: 1009	Post Options Post Reply Quote nunga Report Post Thanks(0) Quote Reply 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
	2nd place HP springer - WFTF World Championships 2014

dvlnme Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 30 May 2017 Location: taranaki Status: Offline Posts: 519	Post Options Post Reply Quote dvlnme Report Post Thanks(0) Quote Reply 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

xyon Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 20 Dec 2016 Location: Canterbury Status: Offline Posts: 135	Post Options Post Reply Quote xyon Report Post Thanks(0) Quote Reply 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.
	--- My favourites springer - Diana 52 PCP - FX Wildcat III

nunga Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Forum Moderator Joined: 08 Mar 2013 Location: Pukekohe Status: Offline Posts: 1009	Post Options Post Reply Quote nunga Report Post Thanks(0) Quote Reply Posted: 26 Jun 2017 at 2:31pm
	you can try flat head cap screws or a button head cap screws they should do the job http://www.steelmasters.co.nz/stainless-steel-fasteners/countersunk-csk-flat-head-socket-capscrews/m6-x-10-g304-csk-socket-screw/afa.asp?idWebPage=41063&CATID=147&ID=101322&SID=932800749
	2nd place HP springer - WFTF World Championships 2014

xyon Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 20 Dec 2016 Location: Canterbury Status: Offline Posts: 135	Post Options Post Reply Quote xyon Report Post Thanks(0) Quote Reply 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
	--- My favourites springer - Diana 52 PCP - FX Wildcat III

nunga Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Forum Moderator Joined: 08 Mar 2013 Location: Pukekohe Status: Offline Posts: 1009	Post Options Post Reply Quote nunga Report Post Thanks(0) Quote Reply Posted: 26 Jun 2017 at 5:38pm
	yep countersink the head into the rail and cut down the screw to suit.
	2nd place HP springer - WFTF World Championships 2014