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6/19/2005 9:34:00 AM EDT
Question for some of you realy knowledgeable guys. (Mongo - I know you know the answer to this one!!)

I've got 3 bolt carriers, and they are all slightly different. By reading all the related threads here and some of the EE postings, I've figured out most of it, but not all.

One of the carriers is a brand new CMT (purchased from RBPrecision), and it has built-up ("enhanced") area beneath the rear end of the firing pin. One is a Colt carrier, and it also has the "enhanced" feature. The 3rd is a DPMS, which does not have the enhancement - the lower area beneath the rear end of the firing pin is cut back about 0.5 inch, thus exposing the rear key screw and the FP retaining pin.

All three are "full circle" carriers (if I understand this correctly), in that the rear ends of the carriers are cylindrical (with a small groove cut into the bottom surface of each). The differences which I don't understand is that the length of these "cylinders" are all different (from the rear of the carrier up to the feed and eject cutouts). The CMT is about 0.75 in., the Colt is about1.6 in., and the DPMS is  only 0.42 in. Are these differences significant functionally? Is one of these possibly an M16 carrier? Can I use these carriers interchangeably?

Thanks in advance for your input.

6/19/2005 9:56:44 AM EDT
[#1]
Sounds like your Colt is a M16 carrier.
6/19/2005 9:58:30 AM EDT
[#2]
I have a LMT M16 BCG and it measures 1.6 inch from the rear of the carrier to the front edge of the cutout.

This is the same dimension of your Colt carrier and I would guess that it's a M16 carrier also.

You could interchangeably use your carriers, but not your bolts. You might try and see which carrier works best on your gun.

I usually use my M16 carrier on my carbines and standard or enhanced carriers on my rifles. YMMV
6/19/2005 10:32:18 AM EDT
[#3]
Thanks for input. Why can't I use the bolts interchangeably? (None of my bolts are "mated" to any of my barrels). Ray
6/19/2005 11:28:27 AM EDT
[#4]
If your barrel and bolt are brand new, then from what I understand, you can interchange bolts (if everything is new).  However, once the bolt and barrel extension wear in and become mated, then swapping bolts between 'mated' rifles can lead to differences in head spacing.  To much or to little head space can lead to catastrophic damage to your weapon.

I think if you replaced your bolt with a new bolt, then it is not suppose to matter.

This is from the info I have read here.
6/19/2005 12:05:42 PM EDT
[#5]
I have one rifle that is on it's 4th barrel and I have reused the bolt every time.  I have headspace guages and it guages out just fine.  I wouldn't go around needlessly swapping bolts but I would not worry about using a bolt over again.
6/20/2005 1:52:53 PM EDT
[#6]
The original design of the whole system was based on the M16 carrier and it's weight.  The M16 carrier is probably the smoothest and most reliable design, but not the most politically correct.  There are no legal issues with running an M16 carrier by itself in an AR, but for some reason, somebody thought it was illegal and started a rampant myth about it.  I actually prefer them, if I'm not using an aftermarket equivalent.  All these carriers are 100% interchangable.  The only worry is the bolt to the barrel fit.  A headspace check is recommended for bolt swaps between barrels.
6/20/2005 5:27:54 PM EDT
[#7]
Thanks to all of you. I learn something on this website every day!!
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