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Posted: 3/16/2013 12:31:42 PM EDT
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There are marks on the neck and the casing running all the way down on some cases.
The place where the extractor grabs the case is very roughed up. Notice the marks on the case neck. The marks on the case and on the head all line up. I am thinking the M4 feed ramps are scratching the case and the extractor is grabbing the case to pull it out a bit to soon before the pressure has come down enough? So perhaps 2 different things going on? Y/M M16 N/M bolt Carbine gas H buffer M855 and PCM 55gr cases Weapon fires fine, has never hung up once on anything Small brass filings in barrel extension and rough case are my concerns I have run about 350 rounds thru it so far 
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Normal.
You're running full power ammo so you very likely could run an H2 and maybe an H3 buffer. That will slow the action and possibly reduce the extractor marks. The longitudinal marks are from the ramps and/or lugs. You can sweep that area with some fine automotive sandpaper on your finger to take the sharp edges off. |
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Yama_raja,
Here's A webpage that talks about gas time of an AR-15. It's worth a read to see if you are having the problems they present, or your weapon or cartridges are showing signs of gas timing being off. http://www.ar15barrels.com/prod/operation.shtml |
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Thanks for the replies gents.
There is a smear on the case head so the timing is off. Its extracting while the pressure is to high. I know I can just run the gun that way but I want it right Going with a H3 buffer to see if that slows things down enough. That way I could always remove one weight if needed and turn it into an H2 if slows down to much. If H3 doesnt do it I see an adjustable block in my future. Also right about the feed lips being sharp 800 wet/dry took care of that. I suspected it was 2 problems at once. Thanks again |
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