Ok. Besides all the legal ramifications and rules I am aware of w/ suppressors and making a short barrel I have a question.

My dept. wants to take some 16” AR’s and put 11.5” barrels on them w/ suppressors. Besides the obvious barrel change is a buffer and/or spring change needed?

Thank you.

quote:

Originally posted by 357fuzz:
Ok. Besides all the legal ramifications and rules I am aware of w/ suppressors and making a short barrel I have a question.

My dept. wants to take some 16” AR’s and put 11.5” barrels on them w/ suppressors. Besides the obvious barrel change is a buffer and/or spring change needed?

Thank you.

Possibly. It depends on the size of the gas ports in the barrels, and how much backpressure is generated by the suppressor. Not all suppressors generate the same kind of backpressure.


If the barrels are ported to run without a silencer(which they almost definitely are), then they will probably be overgassed with a suppressor is in place.



This can be mitigated somewhat by spring rate and/or buffer weight.

There are also options like the Noveske Switch Block, which can allow you to adjust your rifle without tools to be optimized with or without the silencer.

A likely situation is that you will have carbines that function fine without the silencers in place, but are mildly or perhaps majorly overgassed with them in place.


The most likely side effect of this is that you will notice a little more recoil, and possibly a little more gas to the face when shooting suppressed.

It is possible for an overgassed rifle to have function issues because premature unlocking, exacerbating normal wear and possibly breaking extractors over time.

I would recommend that you consult a qualified law enforcement armorer regarding how to optimize your carbines.

I am just a sport shooter, but I do have an 11.5 AR that I use a silencer on. And I know a thing or two about the AR platform.

I demand reliability from my rifles, but I have leeway to utilize equipment that may not be appropriate for law enforcement use. All of my rifles (except clones) have adjustable gas blocks. To me they are an important part of tuning the overall system.

Aside from the Noveske Switchblock, I doubt many LE armorers would be a fan.

Buffers are cheap and easy to change. I find I need an H2 on colt factory 11.5 barrels for what you are describing, but the buffer is the tuning item for an AR. And you don't say what's in tehre now. But that's not full auto, so maybe that changes the situation, no experience. But I can't see the buffer issue as a big one...

All our rifles are 16” Colts. We have 11.5” barrel Colts for the SWAT guys. I have one of those. I have put my own suppressor on it just for fun. I had no problems. But, then it was only 100 rounds.

You should probably contact Colt and see what they recommend.

quote:

Originally posted by hrcjon:
Buffers are cheap and easy to change. I find I need an H2 on colt factory 11.5 barrels for what you are describing, but the buffer is the tuning item for an AR. And you don't say what's in tehre now. But that's not full auto, so maybe that changes the situation, no experience. But I can't see the buffer issue as a big one...

Yes I agree with this. You will probably want H2 buffers.


The gas CAN be a tuning element on some ARs but duty rifles are their own animal and some things are not options because of the .01% chance of failure.


I have more rounds on my 3 gun rifle than most cops will ever shoot and the adjustable gas block still works like new.

But that doesn't mean that liability and reliability concerns don't rule out some options that are available to sport shooters.

Like triggers under a certain weight, and other things.

Most likely be OK chopping a 16 carbine down to a 11.5 for suppressor only with a A5H2 or Tubbs spring/H2. Colt publishes a .062 gas port size for their 16 carbine. Use pin gauges to confirm gas port size. A .062 gas port is just about ideal for a dedicated suppressed 11.5. Still could be slightly over gassed depending on suppressor.. Different suppressor have different back pressure. If it did not function, can very simply drill out the gas port in .001 steps. One thou is a big change! Probably will not function w/o a suppressor.

I have an 11.5 with a carbine +1 gas system with .063 gas port that I spec'd for 100% suppressed TBAC Ulta 7. Runs 100% with MK262 pressure and a little softer handlooads with a Tubbs/H2 or a tuned JP silent captured spring.

Or you could buy a 11.5 barrel that is gas ported for suppressor only use, gas port will be in the .060-.063 range.

There are several variables, gas port size has been mentioned, but Ammo is also a factor. I'm assuming that they will be carbine length gas and not full auto. FWIW BCM uses an H buffer in their 11.5" carbine, Colt uses an H2 in USGI M4s, Specialized Armaments Warehouse packages an H-3 buffer for both their Commando and MK-18 stock kits and H buffer for their longer barrel carbines. What buffer do you have now? Are you going to be using 5.56m or .223 ammo?

I recommend contacting Colt or Specialized Armaments and getting their recommendation. I'd also recommend replacing the existing buffer springs, they an inexpensive wear item and it will not hurt to replace them as long as you use the right parts.

Confirmed a buddies 11.5 set up. He picked up a Colt FBI HRT 11.5 barrel. Way over gassed with his Ultra 7. Put on one of these gas blocks with a .060 insert for 100% suppressed. Runs great with a Tubbs spring/H2.

http://blackrivertactical.com/...Block-750-p102156493

When I added a can to my carbines, I added an adjustable gas block, because factory barrels are over gassed so that almost any ammo will function.

If your dept chops the barrels and adds cans they will need to regulated the gun in general. Be it. Adding a heavier buffer or choking down the gas.

When I did my guns, I made sure my gun would run with any 55 grain regular ammo, by adjusting the gas lock until it worked reliably from the various ammo. Then I was assured the gun would run w/o the added gas of the can.

The amount of gas I get now out of the gun with the can on it is wayyyyyyy less than it was before I added the adjustable gas lock.

Pose this to your departmental Armourer, he should come to the same conclusion.

He doesn't say chop the barrels. And my experience is that factory 11.5" barrels will run fine with a slightly heavier buffer. I'm guessing in this specific case the ammo is known, the barrel is known and the buffer is known to test.

I use an H3 buffer in my Colt 6933 w/ AAC M4-2000. Runs like a top.

An 11.5 with suppressor looks cool but the overall length with the suppressor makes getting in and out of your vehicle and operating in close quarters just as busy as having a 16”. A “suppressor” on any length rifle barrel doesn’t decrease the decibels much. Everyone will still need hearing protection and with a short barrel decreasing much needed velocity and increasing flash and smoke, the suppressor just amplifies all that and blows it back in you face. It is a cool look though.
Either way just do what Knight’s does as your starting point for any configuration and tweak until everything meshes with your chosen ammunition.

I'd be pretty confused by that post. Good suppressors definitely reduce both noise and flash. And you get that in a package that is no longer and can be shorter than the 16" it replaces.

Yea your right. It’s just all that stuff blowing back at you that’s not so nice. Especially indoors. That class I went to kinda put me off to it indoors and in the truck. I think the decibel reduction was like -7 and still over 140 but there’s probably better cans out there.

This message has been edited. Last edited by: Zero1911,

quote:

Originally posted by Zero1911:
An 11.5 with suppressor looks cool but the overall length with the suppressor makes getting in and out of your vehicle and operating in close quarters just as busy as having a 16”. A “suppressor” on any length rifle barrel doesn’t decrease the decibels much. Everyone will still need hearing protection and with a short barrel decreasing much needed velocity and increasing flash and smoke, the suppressor just amplifies all that and blows it back in you face. It is a cool look though.
Either way just do what Knight’s does as your starting point for any configuration and tweak until everything meshes with your chosen ammunition.

Disagree. My 11.5 with a can would be much much more ear friendly with no ear pro than a 16 with no can.