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Posted: 6/11/2014 5:09:59 PM EDT
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I am new to the forum wasn't sure if this was the right place to post this or not but anyways I have seen when bullets get scratched from hitting the feed ramps and it leaves a long scratch down the length of the bullet, well I just noticed on one of my BCM midi uppers that when a round is chambered it leaves like circular marks towards the base of the projectile near the case mouth. I have fired a few thousand rounds through this rifle with no problems to date but I was just curious if anyone else was as anal as me and notice things like this. I am pretty sure the marks are coming from the beginning edge of the chamber it self not sure though.
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It took me a second to figure out this occurrence. As the bullet rides up the ramp, towards the top of the ramp when it pushes forward into the chamber, the top corner edges nick the jacket. I found this out by riding the charging handle to see where the ball was catching. Rounding the corner edges, as the blueprint calls for of the lugs that each feed ramp is between will correct this. Disregard the missing anodizing from the upper receiver (lower portion of M4 ramp) In my diagnosis, I was eliminating out both sections of the feed ramps not messing 100% (I'm not referring to rotational alignment either; though this can affect your bolts lugs when unlocking.)
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