Front Sight loose from firing rifle grenades?

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   Have a GI Inland carbine that used to have a tight front sight.

After firing ten or so Services of Supply rifle grenades using a M8 grenade launcher and blank (not grenade launching rounds) rounds (and several hundred rounds of GI ball), front sight was loose both front back and side to side.

When I removed front sight and key noted that half moon in key was elongated and key was loose laterally in slot in barrel.

Never have heard of this result from firing rifle grenades discussed before. 

In that the M8 grenade launcher is anchored on front sight, is this loosening of front sight and distortion of key, due to forces on front sight when firing a rifle grenade, a common and at one time, well known problem?  

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Jefe73 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Sep 19 2019 Location: Fortson, GA Status: Offline Points: 3	Post Options Post Reply Quote Jefe73 Report Post Thanks(0) Quote Reply Topic: Front Sight loose from firing rifle grenades? Posted: Jan 14 2022 at 9:29pm
	Have a GI Inland carbine that used to have a tight front sight. After firing ten or so Services of Supply rifle grenades using a M8 grenade launcher and blank (not grenade launching rounds) rounds (and several hundred rounds of GI ball), front sight was loose both front back and side to side. When I removed front sight and key noted that half moon in key was elongated and key was loose laterally in slot in barrel. Never have heard of this result from firing rifle grenades discussed before. In that the M8 grenade launcher is anchored on front sight, is this loosening of front sight and distortion of key, due to forces on front sight when firing a rifle grenade, a common and at one time, well known problem?

GotSnlB28 Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Jan 01 2016 Location: WI Status: Offline Points: 843	Post Options Post Reply Quote GotSnlB28 Report Post Thanks(0) Quote Reply Posted: Jan 15 2022 at 8:05am
	I have an M8 setup with a dummy but no M6 cartridges so I haven't been able to test. But I have purchased used front sight keys where the half moon is elongated as you described. The elongation is clean of burrs, etc. My first thought was that when the front sight was put on, the half moon may have not been lined up perfectly with the pin hole, and being as the key is softer metal the pin elongated it when driven through as front sights are often very tight on the barrel. But then I would have expected the edges on the half moon to not be so clean (though it is tight against a keyway). How does your key look, is there any evidence of uneven edges or mushrooming?

Smokpole Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Oct 21 2019 Location: Madison ohio Status: Offline Points: 960	Post Options Post Reply Quote Smokpole Report Post Thanks(0) Quote Reply Posted: Jan 15 2022 at 7:01pm
	I shot plenty of practice grenades from my carbines. I never had any problem from firing them. It sounds like you have a loose sight that was held only by the pin and key and the recoil stretched it. Front sights are normally very tight on the barrel so little or no stress is placed on the key.
	OGCA Life member NRA Life member Ashtabula Rod and Gun Life member

Jefe73 Members Profile Send Private Message Find Members Posts Add to Buddy List Recruit Joined: Sep 19 2019 Location: Fortson, GA Status: Offline Points: 3	Post Options Post Reply Quote Jefe73 Report Post Thanks(0) Quote Reply Posted: Jan 15 2022 at 9:02pm
	Gentlemen, thanks. GotSnlB28, yes, uneven edges and mushrooming. Smokepole, yep, front sight was loose, held only by key/ pin. That must be it.