M16 owners.. Barrel length question

taymag · July 20, 2017, 03:48 PM

So I bought an M16

and was wondering a few things while I wait...

If I pick up a 10.5 upper and its ejecting at 3:00 without any bolt bounce and is running fine is there anything else I need to look into? To be honest I don't think twice about wear shooting my other Ar's, but I feel like I am going to be overly cautious now. When I add a suppressor to my current setups with a 10.5 the extra weight and a brake keeps it from feeling overgassed and running hard enough though it may be, and I really dont think twice cause I shoot it well and it "seems to be running right"

So can I just buy any quality 10.5 and 14.5 upper and as long as I am ejecting around 3:00 and it doesn't feel like its being beat to hell I am good? I feel like I am asking an extremely novice question but I have never had a single worry about "wearing out" my $100 lowers so it never really came up to ask.

I figure maybe a gemtech adjustable suppressor bolt so I can just switch uppers (and take a suppressor on/off) without running/adjusting a block on an a2, and I've seen some reputable people vouch for the bcg toning things down.

Mobuck · July 21, 2017, 06:38 AM

"So I bought an M16 and was wondering a few things while I wait..."
You're talking about a select fire(FA registered lower) rifle?

"If I pick up a 10.5 upper "
That makes it an SBR and that's another application(and stamp).

If you add a suppressor to most any DI platform, it changes the gas volume at/in the system. I haven't any experience with the adjustable bolt assembly so no opinion either.
I have one piston upper for full time suppressor use and others with adjustable blocks if I decide I want to put the can on them.

Theohazard · July 21, 2017, 10:03 AM

Quote:

Originally Posted by Mobuck

That makes it an SBR and that's another application(and stamp).

Not if it's a registered machine gun. A registered machine gun can have any length barrel with no extra stamp needed.

Theohazard · July 21, 2017, 10:20 AM

Taymag, I'm assuming you're talking about a registered full-auto? Sorry if that seems like a dumb question, but often people refer to their AR-15 as an M4 or M16 even when they're just semi-auto.

I'll admit I have very little experience with tuning a full-auto AR-15. I work at an FFL/SOT and I know that my boss uses extra-heavy machine gun buffers in his full-auto ARs. I used one of his lowers with one of those buffers on my 10.5" 5.56 LMT upper with my Saker 5.56 and it ran great.

Typically the best option for controlling gas is to use an adjustable gas block, though those can be finicky and hard to set up depending on which one you get. And I don't know how well an adjustable gas block controls bolt bounce compared to a heavy buffer since that's not really an issue I worry about much.

Under normal circumstances, if you're not getting bolt bounce and you don't seem to be way over-gassed, I wouldn't worry about it. That said, your lower is very expensive and irreplaceable, so tuning the gas down to just as much as you need sure wouldn't hurt (though over-gassing doesn't put much stress on the lower itself).

I have a Gemtech adjustable bolt carrier on my 300 Blackout SBR. I like it a lot, its an easy way to adjust the gas down when you put your silencer on. I want to get one for my 10.5" 5.56 upper.

taymag · July 21, 2017, 05:08 PM

Yes full auto, and I know I will be overly paranoid at first but maybe I will get over it lol. My main reason in asking is cause running suppressed with that weight makes it "seem" way smoother, but "technically" it should be overgassed at that point. And yet the BCG seems like an easier way if I am going to be from suppressed/unsuppressed a few times in a day. I'm still waiting on my form so just trying to get excited while I wait

JT-AR-MG42 · July 23, 2017, 07:36 PM

Colt commercial M16A1 here.

I shoot an 11.5" with either an H2 or a two piece 'dead blow' carbine buffer in addition to the standard upper and buffer.

Both with the A1 fixed stock, just have not found a carbine stock that was comfortable enough for me.

Turned down a length of delrin 1" rod that slides inside the carrier return spring
to act as a spacer in combination with the carbine length buffer in a rifle length stock.

On the whole, I've seen as many headaches with 7" - 10 1/2" barrels as success stories, although you seem to have it figured out.
Happy with my 11.5".
From re-reading your post I'm a bit unclear as to how you are already working with a 10 1/2" and no mention of paper for a sbr. To each his own.

Part I do not understand is how over-gassing is a concern to the lower.
Can only speak from my own experiences - the only lower problems I've seen were all with improperly set-up 9mm blowback uppers.

Elaborate on lower problems from over-gassing, I'm always ready to learn,

JT

July 20, 2017, 03:48 PM	#1
taymag Member Join Date: June 27, 2015 Posts: 79	M16 owners.. Barrel length question So I bought an M16 and was wondering a few things while I wait... If I pick up a 10.5 upper and its ejecting at 3:00 without any bolt bounce and is running fine is there anything else I need to look into? To be honest I don't think twice about wear shooting my other Ar's, but I feel like I am going to be overly cautious now. When I add a suppressor to my current setups with a 10.5 the extra weight and a brake keeps it from feeling overgassed and running hard enough though it may be, and I really dont think twice cause I shoot it well and it "seems to be running right" So can I just buy any quality 10.5 and 14.5 upper and as long as I am ejecting around 3:00 and it doesn't feel like its being beat to hell I am good? I feel like I am asking an extremely novice question but I have never had a single worry about "wearing out" my $100 lowers so it never really came up to ask. I figure maybe a gemtech adjustable suppressor bolt so I can just switch uppers (and take a suppressor on/off) without running/adjusting a block on an a2, and I've seen some reputable people vouch for the bcg toning things down.

July 21, 2017, 10:20 AM	#4
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	Taymag, I'm assuming you're talking about a registered full-auto? Sorry if that seems like a dumb question, but often people refer to their AR-15 as an M4 or M16 even when they're just semi-auto. I'll admit I have very little experience with tuning a full-auto AR-15. I work at an FFL/SOT and I know that my boss uses extra-heavy machine gun buffers in his full-auto ARs. I used one of his lowers with one of those buffers on my 10.5" 5.56 LMT upper with my Saker 5.56 and it ran great. Typically the best option for controlling gas is to use an adjustable gas block, though those can be finicky and hard to set up depending on which one you get. And I don't know how well an adjustable gas block controls bolt bounce compared to a heavy buffer since that's not really an issue I worry about much. Under normal circumstances, if you're not getting bolt bounce and you don't seem to be way over-gassed, I wouldn't worry about it. That said, your lower is very expensive and irreplaceable, so tuning the gas down to just as much as you need sure wouldn't hurt (though over-gassing doesn't put much stress on the lower itself). I have a Gemtech adjustable bolt carrier on my 300 Blackout SBR. I like it a lot, its an easy way to adjust the gas down when you put your silencer on. I want to get one for my 10.5" 5.56 upper. __________________ 0331: "Accuracy by volume." Last edited by Theohazard; July 21, 2017 at 10:25 AM.

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July 21, 2017, 06:38 AM	#2
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	"So I bought an M16 and was wondering a few things while I wait..." You're talking about a select fire(FA registered lower) rifle? "If I pick up a 10.5 upper " That makes it an SBR and that's another application(and stamp). If you add a suppressor to most any DI platform, it changes the gas volume at/in the system. I haven't any experience with the adjustable bolt assembly so no opinion either. I have one piston upper for full time suppressor use and others with adjustable blocks if I decide I want to put the can on them.

July 21, 2017, 05:08 PM	#5
taymag Member Join Date: June 27, 2015 Posts: 79	Yes full auto, and I know I will be overly paranoid at first but maybe I will get over it lol. My main reason in asking is cause running suppressed with that weight makes it "seem" way smoother, but "technically" it should be overgassed at that point. And yet the BCG seems like an easier way if I am going to be from suppressed/unsuppressed a few times in a day. I'm still waiting on my form so just trying to get excited while I wait

July 23, 2017, 07:36 PM	#6
JT-AR-MG42 Senior Member Join Date: December 27, 2008 Posts: 555	Colt commercial M16A1 here. I shoot an 11.5" with either an H2 or a two piece 'dead blow' carbine buffer in addition to the standard upper and buffer. Both with the A1 fixed stock, just have not found a carbine stock that was comfortable enough for me. Turned down a length of delrin 1" rod that slides inside the carrier return spring to act as a spacer in combination with the carbine length buffer in a rifle length stock. On the whole, I've seen as many headaches with 7" - 10 1/2" barrels as success stories, although you seem to have it figured out. Happy with my 11.5". From re-reading your post I'm a bit unclear as to how you are already working with a 10 1/2" and no mention of paper for a sbr. To each his own. Part I do not understand is how over-gassing is a concern to the lower. Can only speak from my own experiences - the only lower problems I've seen were all with improperly set-up 9mm blowback uppers. Elaborate on lower problems from over-gassing, I'm always ready to learn, JT