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Posted: 7/4/2008 4:09:18 AM EDT
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I recently finished a M4 build and spent the last two days shooting it. I ran into a few problems. Once in awhile I get a feed jam. Sometimes on loading from a open bolt and sometimes right in the middle of a mag. Not often.. ejection is forward and once inawhile one case just dripples on to the table. Finally at the end of the day yesterday a empty case got stuck in the chamber. I got the case out and took it down to my shop. I found the extractor spring was thicker and heavier than a spare I had and had a black bumper. I replaced it with the lighter spring with a blue bumper. The gas rings would not hold the carrier when I stood it up on the bolt , so I replaced it with a Mcfarland gas ring. and I polished the feed ramps lightly with the dremel. I noticed a bunch of Brass particles in the locking lug recess of the barrel. Anybody got any other Ideas? The mags are fine and I shot a few differant brands of ammo. Both worked 100% in my other m4. |
So, for an over view: 1- Ensure the bolt and carrier are properly lubed for break-in. I like to go a bit heavy with the lube during this time. 2- Re-install the heavier extractor spring for starters. An o-ring might not be necessary at this point, but could be added insurance later on. 3- Clean the chamber with a GI chamber brush and solvent. 4- Ensure your ejector operates smoothly, apply a drop of lube IAW the Army -10 Operators manual. 5- Re-install your old gas rings, and check for serviceability. |
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