Noise level from 16" vs 20" AR

[Hammer059]

I'm planning on getting a Colt MT6700 in the near future. I would really like the AR15-A4, but it seems they are impossible to find, so AFAIK the MT6700 is pretty much the closest thing and that's what I'm planning on purchasing.

Anyway, not that it matters a whole lot, but for those of you that own both carbine and rifle length AR-15's, do you notice less noise from the 20" than the 16"? If so, how much of a difference?

And since I kinda touched on this in the first paragraph, what are the differences between the AR15A4 and the MT6700? Just the HBAR on the MT6700? Is the MT6700 barrel chromed?

 

[C-grunt]

MT6700 has a chrome lined 1in9 Hbar. I had an older model several years ago. Was an A2 though. Nice rifle but heavy.

Have you considered BCM, FN, or PSA for an A4 rifle?

 

[C-grunt]

http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=AR15A4

Colt A4 in stock.

 

[benEzra]

I don't have any experience with a 20", but I will say that a 16" with a SEI Vortex flash suppressor isn't bad. Avoid anything with a muzzle brake, though; one of the loudest guns I have ever shot next to at the range was a 14.5" AR with an aggressive brake.

 

[Hammer059]

I wouldn't want a muzzle brake, mostly for that reason!

C-grunt, thanks but no it's not in stock. Try adding it to the cart. I'm not asking before I look, I have looked around pretty thoroughly for the A4. If anybody can find me one I'll be astonished.

However, I think I'll be just as happy with the MT6700

 

[C-grunt]

I'd give them a call tomorrow. I noticed that to but it gave me the same message on everything I tried to add to cart. I think the website might be having problems. They are normally pretty good at marking things in stock or not.

 

[briansmithwins]

The muzzle device makes a lot more difference than barrel length.

The worst I've experienced is the old Bushmaster mini Y comp. Those things make the nerves in my front teeth hurt.

BSW

 

[Hammer059]

Ok thanks C-grunt, I'll do that.

Brian: Hah, ouch!

So what exactly are the differences between the A4 and the MT6700? Just the fact that the 6700 is HBAR and different twist? I assume they're both chromed... Same BCG and everything else?

 

[HankC]

If you are talking about 5.56, I had a 20" rifle length AR, don't think it is much quieter, if any, than my 16"s. There is only that much powder in 5.56! 308 would have a huge difference between the 2!

 

[bluetopper]

Try it out of a 14" Contender barrel filled with H335.

Boom and fireball deluxe.

 

[Welding Rod]

With ear plugs I have never noticed a meaningful difference. Without, not sure. I shot my Colt AR15A2 carbine 30 years ago without plugs and I still remember it vividly as it was quite painful. My ears now occasionally ring and buzz and I always wonder if it is related to to that day.

 

[Snowdog]

I don't really see the need for a muzzle brake on anything that has mild recoil to begin with. I put a KDF muzzle brake on my FAL and the difference it made in recoil was somewhat noticeable, but the difference in perceived muzzle blast was atrocious.

If I ever get around to buying something in .338 Lapua or some such beast, I'll make sure I have a brake, otherwise no thanks.

In a mild-recoiling AR15 that's not select fire, absolutely not.

On that note, I've seen brakes made for the 10/22. I have no words....

As for 16" vs 20" in terms of "loudness", I've only ever owned a 16", but a few buddies have 20" ARs and at the (outdoor) range, I've never noticed a difference. Perhaps indoors there's a difference, I wouldn't know.

 

[NWcityguy2]

Anyway, not that it matters a whole lot, but for those of you that own both carbine and rifle length AR-15's, do you notice less noise from the 20" than the 16"? If so, how much of a difference?

There is essentially no difference in noise or concussion, all other things being equal.

 

[C-grunt]

Ok thanks C-grunt, I'll do that.

Brian: Hah, ouch!

So what exactly are the differences between the A4 and the MT6700? Just the fact that the 6700 is HBAR and different twist? I assume they're both chromed... Same BCG and everything else?

Also doesn't have a muzzle device.

 

[HGM22]

http://www.bravocompanyusa.com/BCM-M16-Government-20-Upper-Receiver-Group-p/bcm-urg-gov-20.htm


BCM has the complete 20'' upper in stock.

 

[Hammer059]

Thanks for the responses guys. I was mostly just curious. I think if anything I'll get another M4/6920. I figure if I ever use it indoors I'll have a suppressor on it and I'd rather have the 16" for indoor use. Outdoors, I doubt I'd ever shoot at distances where the extra velocity would make a difference. So I guess I really have no practical need for a 20", although I'll admit I like the look of the classic A2 style rifles..

 

[d2wing]

I have both but haven't really noticed much difference in noise and muzzle flash. For close range there isn't much difference. At longer range the 20 inch will give you a little more bullet effectiveness and the increase in velocity will give you a little more range. My 20 is more accurate but heavier.