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Posted: 5/5/2008 6:20:02 PM EDT
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I began the process of breaking in my new AR-15 (Armalite M-15A4) this weekend and after 50 rounds I noticed that the top of the cam pin was gouging the rear edge of the upper receiver recess as the bolt carrier moved to the rear in the operation cycle. I contacted the manufacturer and was told that this is a rare problem but it does happen. They also stated that once the cam pin cuts ahttp://C:\Documents path the rifle will function without problem. I do not like this answer. There is more happening here than just aluminum being removed. I believe this problem could be caused by one or more of the following: - cam pin out of spec - carrier cam cut out of spec - incorrect index of locking lugs on barrel Has anyone else experienced this problem? I have been through four other AR-15's and this is the first.http:// |
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I can't see your photo's. but have an idea of what you taking about. The cam relief indent edge can get a bit corner-whacked if there is a great deal of slop between the cam and the carrier slot. Instead of the cam turning right away as when the carrier starts to move back, the cam will run straight for a few thousands with the carrier, and catch the corner. Although you don't like to see it, the problem is semi normal on commercial rigs. As for the sides of the key removing anodizing off the upper receiver key slot, that is normal and will be self-limiting as the key mates with the upper track. Bottom line is the B/C is going to mate with the upper receiver (read have it's way) and this is a normal function for break in. Keeping the upper bearing areas of the rifle lubed with CLP will slow this wear (read get a longer service life out of the parts), but it's going to happen on every rig. P.S. Welcome to the site!!! |
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For everyone's reference, here's a picture that works...showing the gouge created by the cam pin: http://i304.photobucket.com/albums/nn198/dconline54868/HPIM0461.jpg |
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