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Posted: 9/27/2010 8:33:38 PM EDT
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In examining the chrome bolt carrier group from my green 601 clone, I noticed it had some noticeable differences from others I have. I was wondering if anyone can shed any light...do the differences indicate a later production date, perhaps?
Here's what I noted...While the carriers themselves look virtually identical, the keys are definitely different. Take a look at these pics: 
I have three BCGs just like "Carrier A"–– including the one in #748, which until I see reason to believe otherwise, I am assuming is all original. Carrier B is the newest acquisition. Do we know when Colt stopped using the full round gas key? I also noted the differences in the bolts (below). Again, do we know when Colt changed from the narrow band to the wide band bolt? The narrow band bolts were earlier, I'm fairly certain. 
The only other difference I noted is a mere possibility. My earliest samples seem to have a sharper radius at the top rear of the carrier cut-out. BUT I have one carrier that I believe is an older one, that has a more curving radius. I need more samples to examine! 
If any of you care to post photos of your slicksided chrome BCGs, please feel free! |
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Carrier A has the "full round gas key" and is the earliest one,carrier B is later and called the 3/4 round, and is what could be found on a late 601,all 602 and and early 604s
The thin band bolt is earliey and can be found 1st with just the P then slightly later with the MP,the P tends to be smaller and almost looks like the M was an after thought.(it basically was, as magnetic partical testing came out some time after the first bolts) Then comes the wide band, the wide band is the one that would be found on the early XM16E1 and early 604. Possibly a very late 602,but that's what I'm not sure about. So,in the case of your 3 digit 601 you want the full round gas key and a thin band P only marked bolt. |
| I don't think any of the 601's would have had anything but a full-round gas key and narrow band bolt. IIRC they changed the gas key in '64-65. That BCG would be correct for a mid-sixties 604 IMO. Colt got the okay to begin parkerizing bolts BCGs from the DoD in '65. DeWatters has much better info than I can offer on his 5.56 timeline. |
I say yes, on the narrow band being earlier too. If you notice the early narrow band has no oil hole for the ejector spring. Wide band and all after have the oiling hole.
But there are always exceptions to the rules. Here is a narrow band bolt with an oiling hole and is marked M P 
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I say yes, on the narrow band being earlier too. If you notice the early narrow band has no oil hole for the ejector spring. Wide band and all after have the oiling hole. http://i240.photobucket.com/albums/ff160/nosepiece/IMG_9814.jpg But there are always exceptions to the rules. Here is a narrow band bolt with an oiling hole and is marked M P http://i240.photobucket.com/albums/ff160/nosepiece/narrowband.jpg Another interesting observation––thanks! I have three thin-bands, all marked P and none of which have the oil hole. Never even noticed that. So we have (so far)... ...thin band, P-marked, with no oil hole; ...thin band, MP-marked, with oil hole; ...wide band, MP-marked, with oil hole. If anyone has other versions (maybe a thin-band, P-marked, with oil hole? MP-marked without oil hole?), please chime in! |
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You guys should IM "Log" about info on his Chromed bolt carrier for details about it. it is the M16A1 version but in chrome. I sold it to him, but no longer have pictures of it. Sounds to me suspiciously like an XM16E1 carrier. Wish I had one like that. (sigh)  Someday.
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I say yes, on the narrow band being earlier too. If you notice the early narrow band has no oil hole for the ejector spring. Wide band and all after have the oiling hole. http://i240.photobucket.com/albums/ff160/nosepiece/IMG_9814.jpg But there are always exceptions to the rules. Here is a narrow band bolt with an oiling hole and is marked M P http://i240.photobucket.com/albums/ff160/nosepiece/narrowband.jpg Another interesting observation––thanks! I have three thin-bands, all marked P and none of which have the oil hole. Never even noticed that. So we have (so far)... ...thin band, P-marked, with no oil hole; ...thin band, MP-marked, with oil hole; ...wide band, MP-marked, with oil hole. If anyone has other versions (maybe a thin-band, P-marked, with oil hole? MP-marked without oil hole?), please chime in! I won't be able to get pics of my chrome bolts, but I have (starting with the earliest): 1) Thin-band, unmarked (w/ unusual extractor shown in pics below) 2) Thin-band, small p-marked 3) Thin-band, large M and small p-marked 4) Wide-band, MP-marked Pics of unusual extractor on earliest bolt: 
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You guys should IM "Log" about info on his Chromed bolt carrier for details about it. it is the M16A1 version but in chrome. I sold it to him, but no longer have pictures of it. Sounds to me suspiciously like an XM16E1 carrier. +1 Very hard to find. |
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I-LUV-AR15s –– That is an interesting bolt––both in the extractor and the fact that it's unmarked. Is there any way to verify that it is a Colt piece? Are the bolts identical other than the extractor and P mark? All of my bolts are genuine Colt and all came from a reputable Arfcommer a couple years ago. As far as I can remember, the bolts are identical except for what I have mentioned. Sorry, I'm out of town for several months, so I can't actually take a closer look at them. Hope this helps you though. Here is the only other pic I have seen of an unusual extractor like mine. This one was from a transferable 601 that was for sale: 
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