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Posted: 3/2/2006 2:19:49 PM EDT
I have a colt 6920 and I just purchased a spare m16 BCG for the weapon.
My original 6920 came with a m-16 BCG however they look different. The differences are in the bolt itself. The spare bolt is marked MPC and has diagonal cuts at the rear edge of the locking lugs. The bolt that came with the 6920 is marked CS and has no diagonal cuts.

Also i notice the bolt carrier that came in the 6920 has a dimpel on the back part of it directly in the middle of the back and the spare one is totally smooth ath the back


So does anyone know why?
Can anyone post a pic of their Colt M-16 BCG
Thanks


Link Posted: 3/2/2006 2:30:39 PM EDT






My bolts range from MPC, to C, to MP
Link Posted: 3/2/2006 2:37:01 PM EDT
redfisher

Thanks for the pics
Do you have any close up pics if the back edge of the bolt lugs

Do your bolts have diaganol cuts at the back edge of the lugs

The dimple i am talking about is 180 degrees from the groove in your second pic and is in the middle.
Link Posted: 3/2/2006 2:49:51 PM EDT
[Last Edit: 3/2/2006 2:59:58 PM EDT by redfisher]
I'll take a couple quick ones

In the interim................here's a text book carrier comparison pic




quick pix




Link Posted: 3/2/2006 3:58:31 PM EDT
Thanks redfisher


The bolt that came with the 6920 looks like your pic however the spare BCG i purchased the bolt is different. I purchased it from SAW and have no doubt that it is a Colt BCG but i just don't understand why they are different. also i can't figure out what the CS marking on my original bolt.

Anyone else have any pics of their Colt BCG particularly the rear of the lugs.
Link Posted: 3/2/2006 4:45:29 PM EDT
I have never seen a colt bolt marked CS
Link Posted: 3/3/2006 7:36:27 AM EDT
Never seen a CS bolt either, but we have seen some odd stuff in regards to Colt bolts/carriers and there markings in the last few years.

In regards to the bolt from SAW, is the M & P run together, or is there a space between them.

Link Posted: 3/3/2006 8:26:58 AM EDT
Ekie
The mpc marking is right on top of each other looks like this MPC
I called colt and they couldn't tell me what the CS stands for they said they will be getting back to me
They also couldn't tell me why there are diagonal cuts on the rear of the locking lugs on the spare bolt. Have you seen this before.
Thanks
Link Posted: 3/3/2006 8:36:13 AM EDT

Originally Posted By PrivatePile:
Ekie
The mpc marking is right on top of each other looks like this MPC
I called colt and they couldn't tell me what the CS stands for they said they will be getting back to me
They also couldn't tell me why there are diagonal cuts on the rear of the locking lugs on the spare bolt. Have you seen this before.
Thanks



The run together MP and the diagonal cut bolt are just how Colt use to make them. I don't think Colt has made them this way since 1982 or so.
Link Posted: 3/3/2006 8:48:22 AM EDT
Ekie

So then this bolt is real old yet I just purchased it and it is sealed in a bag marked
MIL-B-117G
TY. 1-CL. B-ST2
EDCO 10/01

I guess i am going to return it. Where can I get one that doesn't have these diagonal cuts.
Thanks
Link Posted: 3/3/2006 8:58:26 AM EDT
[Last Edit: 3/3/2006 9:03:29 AM EDT by Ekie]

Originally Posted By PrivatePile:
Ekie

So then this bolt is real old yet I just purchased it and it is sealed in a bag marked
MIL-B-117G
TY. 1-CL. B-ST2
EDCO 10/01

I guess i am going to return it. Where can I get one that doesn't have these diagonal cuts.
Thanks



Brain storm here..........

Hmm, that is a more current bag. Don't know what to tell you. You are going to have to post pictures before I weigh in 100 percent that your bolt is an old one.

Another clue, what color is the extractor buffer?

Another clue, firing pins from the 1970's have a heat treat mark on the head of them. Current production do not.

Another idea, I have received old parts that were just released from Colt.

Any how, even if it is a 24 year old bolt, a new one is not going to be any better of a part.
Link Posted: 3/3/2006 9:05:09 AM EDT
Do you have or could you post a picture of this odd bolt?


For new Colt M16 BCG you could contact and I recommend Jim (dealer name GunDealer3).
Phone: (850) 622-6251
e-mail: jim@policesupplyinc.com
website: www.policesupplyinc.com
Link Posted: 3/3/2006 9:12:32 AM EDT
Ekie

I didn't cut the bag open once I noticed the diaganol cuts I didn't think i had recieved the correct part.
Do you know why colt stopped making the bolts with the diagonal cuts?

Thanks again
Link Posted: 3/3/2006 9:47:07 AM EDT

Originally Posted By PrivatePile:
Ekie

I didn't cut the bag open once I noticed the diaganol cuts I didn't think i had recieved the correct part.
Do you know why colt stopped making the bolts with the diagonal cuts?

Thanks again



The why has to do with how the bolt bevel is cut on the left side of the locking lugs. Not being familiar with machining I can't say why.

Have seen such cuts show up in later bolts, but it is rare. For example I have a 1995 Colt both that has them, but that bolt has a space between the M and the P.

But, there is a limit here on what I can tell you about a bolt group you describe to me that is still in the wrap.

Like I said before, if it is an old bolt a newer one is not going to be any better, save perhaps the extractor spring/buffer.
Link Posted: 3/3/2006 9:56:40 AM EDT
[Last Edit: 3/3/2006 10:30:34 AM EDT by Ekie]
Here are some examples.

Colt bolts from late 1967 until the early 1980's are very consistent in marking and machining, they look like this:



Note the diagonal cuts and the MP ran together. Color can be anywhere from light matte gray, to a near blue looking black.

More recent production bolts vary quite a bit on how they are marked. Typically they look like this:



They tend to be a light matte gray, and so far the M & P are spaced.
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