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Posted: 5/13/2011 2:28:34 AM EDT
This is the inside of a BCM upper after about 500 rounds. You can see the long wear mark. Is this normal wear?
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500 rounds,NO.
Your upper may have been to shallow or your bolt carrier is to loose on the upper but most likely your gas key is the problem? Maybe the gas key is bent up slightly and someone bent the gas tube up to match. The rifle would have test fired fine but now the problem showes up |
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Normal. That is made by the charging handle. Ignor the other three. This is the correct answer as long as the charging handle isn't dragging when you manually cycle it. The gas key can't even touch the top of the receiver because there is a charging handle inbetween the key and receiver. |
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Normal. That is made by the charging handle. Ignor the other three. This is the correct answer as long as the charging handle isn't dragging when you manually cycle it. The gas key can't even touch the top of the receiver because there is a charging handle inbetween the key and receiver. The gas key is inside the CH trench/canal. Wear in that area is caused by contact of the top of the CH on that area everytime you use the charging handle to lock and load! |
| I stand corrected. Above posters are right. The charging handle makes contact in that area, so you need to look at the top of your charging handle. And as little as you pull the charging handle, that looks like a lot of wear, was it hard to cycle? Maybe something got caught up under the charging handle. |
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Normal. That is made by the charging handle. Ignor the other three. This is the correct answer as long as the charging handle isn't dragging when you manually cycle it. The gas key can't even touch the top of the receiver because there is a charging handle inbetween the key and receiver. It is extremely smooth when I manually cycle it. |
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See that little nub on the end of your charging handle - the shiny part - that's what's doing it. Once the two parts wear themselves enough (looks like it's already been done) it will stop. Winner! I knew thet when I saw the pictures. In fact a similar picture dashed through my mind when I saw the words BCM, 500 rds and Wear in the title. Any receiver made by (or outsourced) by any mfg or seller can do this. |
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New out box, after ... five rounds
Sabre Def. 
Uploaded with ImageShack.us Mister Moon for http://www.m9m4.com/index.cfm?fuseaction=engine&idcategory=1¤tpage=32 |
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I would say no, what does the top of your gas key look like? Here is the BCG and CH. The BCG a spikes that I blacked the spider out on. I am no expert but it seems to be ok. http://i1227.photobucket.com/albums/ee431/gangway83/DSCF2965.jpg http://i1227.photobucket.com/albums/ee431/gangway83/DSCF2970.jpg http://i1227.photobucket.com/albums/ee431/gangway83/DSCF2961.jpg Is that a crack in your CH latch or my eyes are playing tricks on me? |
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I would say no, what does the top of your gas key look like? Here is the BCG and CH. The BCG a spikes that I blacked the spider out on. I am no expert but it seems to be ok. http://i1227.photobucket.com/albums/ee431/gangway83/DSCF2965.jpg http://i1227.photobucket.com/albums/ee431/gangway83/DSCF2970.jpg http://i1227.photobucket.com/albums/ee431/gangway83/DSCF2961.jpg Is that a crack in your CH latch or my eyes are playing tricks on me? It was oil or something in the pic. I just checked and its not cracked. Thanks for stoking my OCD though. 
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Thanks for stoking my OCD though. That got me laughing! My best buddy worries about things so badly, that I have to be careful what I say when he asks for advice on ANYTHING. He is such an intense dude (and very large ex Marine), that things go critical real quick when he starts to obsess. I love the guy like a brother, so I feel it is my responsibility to help keep him sane. |
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Thanks for stoking my OCD though
Hahaha, man I hear you! I started worrying about MY setup when I was reading this, lol. I shoot it quite a bit, but I obsess over all the marks, spots, etc., when I'm cleaning. That and extraction/ejection marks on my brass. I'm a nutjob over this stuff, unfortunately. It's why I had to get out of turbo-charged cars as a hobby. Just too many noises and potential problems! 
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