Gunsmithing MIRS screw issue

onechance

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Minuteman
Oct 1, 2003
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I've got a MIRS mounted on my FN SPR A3G. I was shooting the other day and my shots were all over the place with the first 5 shots. This rifle will stack shots normally at 100 yards.

I checked to see if the scope rings were loose, but it turned out to be the mount. I removed the scope and looked down in the screw holes and noticed one of the heads was missing. I started to remove the others, but the heads popped off the other 3 with little effort.

I was lucky that they did not crack off in the receiver. I was able to remove the screws with pliers. All the heads cracked off at the top of the screw. There was no rust, bends or deformation. I placed the screws as per McCann's instructions. I tried to call McCann's, but no one answers, I was hoping they could explain this issue.

I think that possibly that there was an issue with heat treatment of the screws. What do you guys think?
 
Re: MIRS screw issue

Torqued to specs. I spoke with Debbie @ McCann Industries, she mentioned, that there were issues in the past with the screws. She's sending me a new kit today. Thanks for looking guys!