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Posted: 12/25/2003 12:30:58 AM EDT
Well, I took the PWA out again today and put about 100 rounds through her.  Cleaning tonight I noticed some serious finish wear inside the upper.  It looks like the bolt carrier is rubbing away the finish.  Is this normal and if it isn't should I replace the carrier.  This pisses me off because I have never had this hapen in an AR I've owned before.  There is corresponding wear on the carrier so I know something's rubbing.  Also,  When I close the upper on the lower, the rear of the carrier takes a gouge out of the face of the buffer.  What the hell is wrong with my weapon???
Link Posted: 12/25/2003 12:37:23 AM EDT
Well, I know this is not much help, but maybe your carrier just sucks, try another.  It's normal for some carrier/receiver wear as they break in and wear into each other, but not excessively so.  One and/or the other may be slightly tight, but I don't see why it should gouge the buffer as the rear of the carrier face should be flat, unless you are using an open circle carrier and the corners are sharp and scrape the buffer.  If it really freaks you out, I would just swap the carrier out.  However, I am no guru.  You need TWEEK or somebody who knows what they are talking about...
Link Posted: 12/25/2003 5:48:45 AM EDT
Note that the carrier has four long "ribs" that are the actual contact points between the carrier body anf the inside of the upper receiver (toal of eight surfaces).  So the only wear marks inside the UR should be along those lines.  Correspondingly, these are the only areas that demand lubrication.  I have never trusted an "oil" to provide lubrication and protection to these four corresponding surfaces because thery are so narrow and gravity is working against four of the eiight surfaces, consequently, I like a light grease, something like TW-25 unless you are in very cold weather.
The two most common(of the 8) "normal" wear marks should appear as "burnishments" along the inside roof of the UR caused by the two bolt carrier ribs alongside the carrier key ( i.e., gas tube).  The degree of burnish or outright wear threw the black anodization into the base aluminum is somewhat dependent on how much pressure is pushing up on the carrier from the top round in the magazine, as every time the carrier reciprocates, its being pushed straight up by action of the compressed magazine spring. SO if you have taken apart your magazine and stretched the spring to obtain more positive feeding, the back end of such compromise is increased friction between the top of the bolt carrier and the roof of the UR.
Likewise, if the LR magazine catch slot is machined "a little high", then this would aggrevate the situation.
But probably the mose likely cause is a less than mil-spec hard coat anodization applied to the inside of the UR, lack of proper lubrication, etc.
Also, using an extended charging handle latch will twist the front end of the handle and cause asemtrical wear areas to both the hanle and the UR, where they would not normally occur if one used the standard handle and used two fingers to pull it backwards symetrically.
On the face of the buffer, I have seen this several times.  What I do is chamfer the the edges of the inside bore, and lightly stone the rear face of the bolt carrier looking for "high spots."
If this does not help, then maybe the aluminum buffer material is not proper, but was selected for ease of machining or manufacture, vs what the US Gov demands.  I find many non mil-spec parts out there that are just cheap shit.  They may look good, but after a few hundred rounds they give it up.
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