M4 carbine bolt

[trbon8r]

With the exception of the different extractor insert (black vs. blue) is there any difference between the M4 carbine bolt and carrier assembly and the basic M16 bolt and carrier assembly?

Without wanting to get into a Colt vs. (fill in the blank) argument, is there really any reason to pick a Colt bolt carrier over a CMT assuming you buy a CMT with the MP tested bolt? Thanks.

 

[sarduy]

i believe that AR-15 and M4 carbine use the same bolt assembly as long as the M4 is a semi-auto version, and yes you can use M16 bolt and carrier in a Ar15 or M4, but not the auto sear or trigger system, because that would make it illigal to own unless you do the paperwork and pay for the tax.

as a general rule; AR-15, M4, M16 AND AR-PISTOL can use the same Bolt assemby, as long as it keep it semi-auto,(legal to own, without any paperwork or tax stamp) and use the same caliber.

 

[nicholst55]

I can state with some authority that the M16 series of rifles and the M4/M4A1 carbine use the same bolt and carrier with the exception of the extractor spring and insert. The rifle uses a black-colored spring and black insert; the carbine uses a gold-colored spring with black insert. The carbine spring has one more coil than the rifle spring.

I don't know if the gold springs are available commercially from Colt (or anyone else), but Wolff makes an extra-power extractor spring. Try that, a black insert, and a #60 O-ring around the spring for the problem rifle or carbine.

Edited to add: I checked the latest change to the TM (Change 8) when I went back to work, and found that I was mistaken about the color of the current M16-series RIFLE extractor spring - it is silver-colored, rather than black. The insert is black, as mentioned earlier.

 

[taliv]

the M16 carrier is different than the AR15 carrier as sarduy mentioned.

 

[Bartholomew Roberts]

With the exception of the different extractor insert (black vs. blue) is there any difference between the M4 carbine bolt and carrier assembly and the basic M16 bolt and carrier assembly?

The M4 also uses a stronger extractor spring in addition to the different insert.

Without wanting to get into a Colt vs. (fill in the blank) argument, is there really any reason to pick a Colt bolt carrier over a CMT assuming you buy a CMT with the MP tested bolt?

The Colt bolt should also be shot-peened and have the correct surface hardening. I imagine the CMT bolt will have the correct surface hardening; but probably isn't shot-peened.

Realistically, none of my rifles have the shot-peened, MPI, etc. bolts and they are all doing nicely in fairly demanding shooting (500+ rounds in a day with a lot of suppressed usage - though I haven't done much shooting this year.)

 

[johnson_n]

From ar15barrels.com

 

[Soybomb]

Without wanting to get into a Colt vs. (fill in the blank) argument, is there really any reason to pick a Colt bolt carrier over a CMT assuming you buy a CMT with the MP tested bolt?

What BR said, plus note that colt proof fires every bolt and then MPI's every bolt. I believe CMT fires no proof loads and only MPIs a percentage of each lot. How important is it? Thats probably up to the user to decide. Most of us are casual plinkers and a bolt failure doesn't mean anything.

 

[cbrgator]

Arent LMT BCG's supposed to be excellent as well?

 

[Onmilo]

Lewis Machine and Tool bolts and carriers are excellent too.
If you aren't shooting a full automatic M4 Type carbine you will see no benefit from spending the extra money on an LMT enhanced bolt and carrier,

Colt does offer both carbine and rifle extractor springs seperately to the commercial market.

 

[taliv]

compared to what, onmilo?

 

[Gary G23]

The only BCG I will buy is this one:

http://www.bravocompanyusa.com/BCM-...Auto-M16-p/bcm bolt carrier group auto mp.htm

 

[Sgtanderson]

I Love my M-4, my Uncle Sam gave me a high speed Sure Fire light to go on it and Aimpoint sight and a Gangster lookin tommygun handle witha pop-out bipod. Hell what more can a soldier ask for? OK I took the Beretta 9 mil also but they offered it!

 

[Ragnar Danneskjold]

Could someone in the armed forces use a civilian AR bolt carrier in a .gov FA M4? I'm thinking that pulling out the bolt carrier for some cleaning during down time while deployed is a great idea, but I don't want to take my weapon out of commission. Could I pull the M4 bolt carrier out, put the AR one in, and still have a working weapon while I scrub the dirty M4 one?

 

[Rubber_Duck]

Yes, but the full-auto feature will be lost with an AR bolt carrier, because it lacks the "fullness" in the rear to trip the auto sear. Otherwise, the two will interchange just fine. If you are buying a backup BCG, might as well get the FA one if you have the choice.

 

[Sgtanderson]

Hey Sarge- If ya switch bolts just dont tell anyone---the Armorer might get kinda pissed about that,not to mention Top and a few others in the chain!And dont forget to switch'em back. just a thot.

 

[Onmilo]

Compared to a standard LMT or Colt bolt and carrier.
That is what is being discussed here right??