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Posted: 6/22/2005 5:51:47 PM EDT
| im buying a colt a1 upper and the description says its marked c mp c. what does this mean??? |
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1st C= Colt MP= Magnetic Particle Tested 2nd C= Chromed Chamber A Colt with Chromed Bore would be denoted by the stampings "CB" or "CHROME BORE" If it is a M16/AR15 Full Auto Upper, and post 1970, it will more than likley have a Chromed Bore, even if it is not stamped "CB" or "CHROME BORE" You can identify the particulars by logging on to: www.biggerhammer.net and going to: AR15/M16 FAQs |
If it says MP means Magnetic Particle, then yes it is wrong. The P is for Proof fired. Early bolts were just marked P. |
Yet another Colt people checking in!  Proof load firing is actually a pretty interesting (and dangerous) process. An M197 high pressure test (HPT) round is fired to expose any cracks, flaws, or imperfections in the barrel. Once the proof load has been fired the barrel is then magnaflux particle inspected to detect any potential problems. In case anyone here cares about worthless trivia, here is a pic of an M197 high pressure test round (the silver case, 4th one down): 
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Not only don't forget it---it's the correct designation for early fully chromed barrels  There is no "CB" barrel; unless he was referring to C MP B. While there were some very early 1 in 12 barrels marked "12" to delineate them from the very earliest 1 in 14 twist experimental jobs, the overwhelming majority of the pre A2 types were marked either: C MP (totally unlined) C MP C (chrome chamber)* C MP B (chrome chamber and bore, early) C MP CHROME BORE ( later fully chromed) *We've had some posts from people who swear they have fully chromed C MP C barrels, but I've never seen one, nor do I know anyone personally who has. |
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To RAMBOSKY and CJAN..hey fellas I didnt mean to make you feel segregatedHey I used to be a Colt rifle people model 6601 HBAR..I have to admit though all 4 of my 1911s are Colt.I love Colt 1911s because every thing wilson combat makes is geared to Colts dimensions
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I know, I was just having some fun with ya! |
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Ill tell ya though CJAN I have seriously considered a 6920 and sending out the lower to the smith that does the FCG pin holes to standard diameter..its like $300 to have done but I figured $1500 is not bad to have the rifle as close as possible to satisfy my neuroticism with the FCG being a standard size.I have a Dealer who can get one around my way for a little over $1100.Im to a point now where 4 Bushmasters and an Armalite and RRA is enough Im doing the collecting an AR from the best companies thing and with that train of thought I think its time for a Colt again.
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Well, maybe I can persuade you with the virtues of large pins  From a standpoint of long term wear, the larger pins have more bearing surface-and will go longer before wearing out the holes in the lower. I know, I know, since we're talking about semiauto it's weak-but it's all I could think of on such short notice ETA: If it's a matter of compatibility with your current parts inventory I will gladly donate a spare large pin factory Colt FCG for you to have onhand 
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Thanks CJAN..Ill be getting my Colt in the next few months and I will definatel take that FCG off your hands..thanks.Im starting to mellow back in 92 when I had my first Colt parts were no where to be found but now are alot easier to get...so the larger diameter I guess is no big deal besides spare parts are cheaper then spending $400 just to have smaller pins..thanks again
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