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#4671789 - 02/20/18 11:07 AM AR-15 vs. M-16 Bolt Carrier Group ??
billt460 Offline


Registered: 03/30/15
Posts: 4411
Loc: Glendale, Arizona
Got a question for you AR guys. With all other things equal, (Buffer tube, and buffer tube spring), is running an M-16 bolt carrier group easier on the gun than an AR-15 bolt carrier group is? What I mean is, I swapped out the stock AR-15 bolt carrier group from one of my Bushmaster M-4's, and installed a Nickel Boron Coated M-16 bolt carrier group from Aries Armor. The gun runs fine. Both feeds and ejects beautifully. I'm thinking with the added mass of the M-16 BCG, it will be somewhat easier on the gun because it will slow down the cycle time.

Am I right or wrong? I'm asking because I have another BCM, M-16 BCG I'm thinking of putting in my other Bushmaster 20" rifle. I figure since I have the thing, why not use it? I bought it for an "emergency" spare. But I figure I'll run it and keep the original as a spare. I would rather not start switching buffer tubes and springs. Especially since what I've got already in there is working fine. What do you guys think? This is the M-4, and the 20" rifle I want to put the BCM, M-16 BCG in.






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#4671796 - 02/20/18 11:16 AM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: billt460]
Reddy45 Offline


Registered: 08/15/08
Posts: 2973
Loc: USA
That's rifle length gas right? I suppose you added some cyclic mass with the M16 carrier, but your gas system should already be optimized.

On the other hand if you ever buy yourself a pre-86 full auto lower, then you're all set for FA fire. Other than that, it's just minor differences.

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#4671972 - 02/20/18 02:02 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: billt460]
BlueOvalFitter Offline


Registered: 02/28/03
Posts: 6003
Loc: Cajun Country, La.
I will only use M16 BCG's in my AR's. And yes, it does slow it down a bit. I could actually tell the difference with the very 1st one I replaced. I use ToolCraft or PSA. And, I think ToolCraft makes BCG's for PSA.

http://www.monmouthreloading.com/shop/toolcraft-5-56-nato-black-nitride-bolt-carrier-group/

http://palmettostatearmory.com/psa-5-56-...logo-39339.html

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#4671986 - 02/20/18 02:15 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: billt460]
i_hate_autofraud Offline


Registered: 05/19/16
Posts: 706
Loc: Canada


Did you use go / no-go chamber gages to be sure clearances with a changed bolt is OK?

I understand the internal anti-bounce weight is different then the semi!

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#4672007 - 02/20/18 02:32 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: billt460]
bubbatime Offline


Registered: 03/18/08
Posts: 5627
Loc: South Florida
Yes the added mass is a good thing. Basically the same thing as adding an H-buffer. The additional mass slows cycling down, which allows the brass to contract, and puts a little less strain on the extractor and other components.

As to buffer springs, they really only have a life span of about 3000 to 5000 ish rounds before they need replaced. The aftermarket space age springs work good, but I've always just replaced my buffer springs with a $2 G.I style replacement. They are cheap enough to just replace.
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#4672020 - 02/20/18 02:43 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: i_hate_autofraud]
Reddy45 Offline


Registered: 08/15/08
Posts: 2973
Loc: USA
Originally Posted By: i_hate_autofraud


Did you use go / no-go chamber gages to be sure clearances with a changed bolt is OK?

I understand the internal anti-bounce weight is different then the semi!


Headspace on an AR is set with the bolt head and the barrel extension. The bolt carrier has no impact on headspace.

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#4672034 - 02/20/18 02:52 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: bubbatime]
28oz Offline


Registered: 04/20/17
Posts: 344
Loc: Utah, USA
Originally Posted By: bubbatime
....The additional mass slows cycling down, which allows the brass to contract.....


Interesting. Was wondering what benefit a heavier BCG could provide. Then I got to wondering if this would apply to steel casings as well? My Rock River AR hates steel cases. They will randomly stick solid in the breach forcing me to ram them out with a cleaning rod (it is flawless with brass cases). Of course, the lacquer or whatever polymer covering on the steel cases contributes to this sticking, I'm sure.
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1990 Nissan 300zx - Castrol Edge Euro 0W-40
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#4672073 - 02/20/18 03:38 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: bubbatime]
billt460 Offline


Registered: 03/30/15
Posts: 4411
Loc: Glendale, Arizona
Originally Posted By: bubbatime
Yes the added mass is a good thing. Basically the same thing as adding an H-buffer. The additional mass slows cycling down, which allows the brass to contract, and puts a little less strain on the extractor and other components.

As to buffer springs, they really only have a life span of about 3000 to 5000 ish rounds before they need replaced. The aftermarket space age springs work good, but I've always just replaced my buffer springs with a $2 G.I style replacement. They are cheap enough to just replace.


Thanks Bubba. That's pretty much the information I've read, and why I went to them. And when it comes time to change out buffer springs, I'll use the G.I. style as well. They work well and have a fairly good service life. And you can't beat the price.

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#4672336 - 02/20/18 07:05 PM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: 28oz]
BlueOvalFitter Offline


Registered: 02/28/03
Posts: 6003
Loc: Cajun Country, La.
Originally Posted By: 28oz
Originally Posted By: bubbatime
....The additional mass slows cycling down, which allows the brass to contract.....


Interesting. Was wondering what benefit a heavier BCG could provide. Then I got to wondering if this would apply to steel casings as well? My Rock River AR hates steel cases. They will randomly stick solid in the breach forcing me to ram them out with a cleaning rod (it is flawless with brass cases). Of course, the lacquer or whatever polymer covering on the steel cases contributes to this sticking, I'm sure.

Add a BCM extractor spring upgrade kit and this will cure the problem. BCM states that the o-ring is not needed. I tried without/with. It extracted the steel casing much better with the o-ring.

https://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm-exspring-1.htm

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#4672618 - 02/21/18 12:01 AM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: billt460]
bubbatime Offline


Registered: 03/18/08
Posts: 5627
Loc: South Florida
You want the Colt Gold spring for the AR extractor. There was a high dollar spring comparison done and the Colt was the winner. It was found to be the most durable, with the proper spring tension (you can have too much, or too little). Just the spring and black insert by itself, no o-ring needed (or desired)

All of my rifles have these and I can confirm that they are on the money.

https://www.brownells.com/rifle-parts/bo...y-prod4840.aspx
_________________________
17 Chrysler Pacifica Mobil 1 5W30
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12 Suzuki S40 Rotella 15W40
10 Acura TSX 2.4 PZL Plat 5W30
06 GMC Sierra Nextgen 10W30



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#4672639 - 02/21/18 01:11 AM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: bubbatime]
BlueOvalFitter Offline


Registered: 02/28/03
Posts: 6003
Loc: Cajun Country, La.
Originally Posted By: bubbatime
You want the Colt Gold spring for the AR extractor. There was a high dollar spring comparison done and the Colt was the winner. It was found to be the most durable, with the proper spring tension (you can have too much, or too little). Just the spring and black insert by itself, no o-ring needed (or desired)

All of my rifles have these and I can confirm that they are on the money.

https://www.brownells.com/rifle-parts/bo...y-prod4840.aspx

BT, what makes this spring better than the BCM spring kit?

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#4673052 - 02/21/18 10:44 AM Re: AR-15 vs. M-16 Bolt Carrier Group ?? [Re: BlueOvalFitter]
28oz Offline


Registered: 04/20/17
Posts: 344
Loc: Utah, USA
Originally Posted By: BlueOvalFitter
Originally Posted By: bubbatime
You want the Colt Gold spring for the AR extractor. There was a high dollar spring comparison done and the Colt was the winner. It was found to be the most durable, with the proper spring tension (you can have too much, or too little). Just the spring and black insert by itself, no o-ring needed (or desired)

All of my rifles have these and I can confirm that they are on the money.

https://www.brownells.com/rifle-parts/bo...y-prod4840.aspx

BT, what makes this spring better than the BCM spring kit?


Thank you both for that info. I will look into them. Thanks!
_________________________
-----------------
1990 Nissan 300zx - Castrol Edge Euro 0W-40
2004 Nissan Quest - Pennzoil Platinum Euro 0W-40
2003 Ford Excursion 7.3 PSD - Mobil 1 TDT 5w-40

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