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Posted: 12/28/2003 11:26:28 AM EDT
is there any fix to tighten up the upper and lower receiver at the front hinge pin?  my gun seems to have play at the front hinge pin and allows the upper to move.

Link Posted: 12/28/2003 5:27:04 PM EDT
You can buy shim stock form Brownels. Cut to fit and drill the hole for the pivot pin.
Do not use your upper or lower as a drill guide.
Instead, buy yourself a set of center punches from Harbor Freight to mark the hole.
Drill the hole a bit larger than the pivot pin.
Shim both sides equally to keep the upper centered. The shim stock kit comes in different thicknesses.
My Colt lower measures .500 between the ears, my BM upper measures .497 on the stub. It has some play but I left as is with no shimming.
Be advised, the shims will fall out when the upper is removed. You may try to epoxy them to the upper stub, but the epoxy may add to much to the shim and the upper stub will be to wide to fit in the lower.
Link Posted: 12/28/2003 9:16:08 PM EDT
The marine corps tech manual shows the gauge that is used to mesure the space between the 2 front pivot holes.Although shimming is a quick fix the manual does give examples of when its too loose up front that the receiver becomes unserviceable.
Link Posted: 12/29/2003 5:31:08 AM EDT
[url=http://www.bushmaster.com/shopping/gunsmith/artp.asp]EXPANDABLE TENSIONING PINS[/url]
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