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Quoted:
Looks like a Colt transitional BCG to me. . . What makes identifies it as GM? I was told by another member that the bolt was a GM. I am not familiar with the GM bolt markings. I do know that the bolt carrier is a Colt. I am thinking it is a transitional carrier, but not sure since I have never seen one up close. I have never seen another bolt carrier finished like this one. |
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Far as I know, "Transitional" just means it's vintage and a mix of chrome and parked parts. You have a parked Key, with later style staking, on a chrome, carrier marked with a C ('67 or later).
The Bolt itself looks like the colts I have/have seen, MP marked, with the little diagonal tick marks behind the lugs. I would be curious to know what identifies it as GM? The only odd thing that struck me about the bolt, is the surface texture on the neck behind the lugs. It almost looks pitted, but it's all chrome, so. . . ? Most I've seen have been smooth, or had machining marks (fine ringed or diagonal ridges). |
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Quoted:
Far as I know, "Transitional" just means it's vintage and a mix of chrome and parked parts. You have a parked Key, with later style staking, on a chrome, carrier marked with a C ('67 or later). The Bolt itself looks like the colts I have/have seen, MP marked, with the little diagonal tick marks behind the lugs. I would be curious to know what identifies it as GM? The only odd thing that struck me about the bolt, is the surface texture on the neck behind the lugs. It almost looks pitted, but it's all chrome, so. . . ? Most I've seen have been smooth, or had machining marks (fine ringed or diagonal ridges). I am hoping that someone who is really familiar with the older bolts and carriers can weigh in. My main interest for knowing is that I need to be able to know if I need to use a partial-fence or full-fence lower for my 604 build. If the BCG is early enough and correct enough for an early 604, I would really like to use a partial-fence lower. |
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Sorry, I stand corrected. - http://bpullignwolnet.dotster.com/retroblackrifle/ModGde/RflGde/604.html
Admittedly, I am not the uber-knowledgeable person you seek, but it seems like it fits the bill to me. I'd build with a partial fence. |
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jrs93accord, if you're looking to do an "early" 604, the carrier you have is post 1968. Colt didn't mark their carriers with the C until GM and H&R got their contracts in 68.
I was also under the impression that only Colt bolts have the "tick" marks behind the lugs as mentioned above. I could be wrong on that as I never studied the non Colts. |
| Looks like a late production 69+ Colt carrier and a GM bolts. Colt MP marked bolts don't have the M and the P joined together. A joined MP running left to right is a GM characteristic. And some GM bolts have the slash machine mark like Colt bolts. A joined MP running front to back would be an H&R bolt. |
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It's not a chromed carrier, it was parked at one point. Some G.I. or most likely series of G.I.'s cleaned the hell out of it with wire brushes and who knows what kind of chemical concoction.
We liked carburetor cleaner and sometimes brake cleaner...you know, whatever was cheaper in the auto care section at the shopette.  
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Quoted:
jrs93accord, if you're looking to do an "early" 604, the carrier you have is post 1968. Colt didn't mark their carriers with the C until GM and H&R got their contracts in 68. I was also under the impression that only Colt bolts have the "tick" marks behind the lugs as mentioned above. I could be wrong on that as I never studied the non Colts. The tick marks were present on both GM and Colt bolts. Both GM and Colt bolts have the MP markings, but Colt had their MP bolts separate, whereas GM has the markings running together (which is interesting to note, since on all C MP C or MP C barrels for ALL makers, the MP are joined together, even on the Colt barrels. H&R did not have tick marks, but the MP ran latitudinally across the bolt face. v/r, Jon |
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Quoted: Irregardless of who made the bolt I would want the head space checked on it along with the barrel. That bolt looks pretty beat. I love having retros with all original parts, but I wouldn't risk getting hurt over it. Stay safe  
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