Suppressors 30 Caliber Suppressor on an AR-15 Question

[Longshot231]

I've been thinking of putting a 30 caliber can on a 5.56mm AR-15 to avoid a lot of the back pressure and subsequent need for any weapon modification.

I was wondering if anyone has attempted this and what were your results?

 

[Zak Smith]

It will reduce backpressure, but not eliminate it. I shoot gas guns like that all the time.

 

[Longshot231]

It will reduce backpressure, but not eliminate it. I shoot gas guns like that all the time.

Thanks for the information.

I'm thinking of putting a QB 30 caliber on the AR-15. I am not into doing mag dumps so it is not like I'm worried about overheating the can or building up a lot of fouling in the action.

The comments that I've read on the QB is that, other than heavy, is that the drilling fixture they provide has a larger than normal hole for the caliber it is intended for.

My guess is that they do that is to mitigate the chance of a baffle strike as they have no control on drilling the holes or the host weapon.

Anyway, my theory is that even though it's for a 30 caliber the amount of gas blowing by the projectile would be even more and thus avoiding a lot of back pressure.

 

[Kadams1563]

Just about everyone puts a .30 cal can on their 5.56 guns. I would say most suppressor users are. It using 5.56 dedicated cans.

regardlessit will add a pretty good amount of back pressure unless you get something like an OSS can. My 11.5 runs like a top with my can attached. If I take the can off the bolt doesn’t even cycle enough to pick up another round. Half the time it doesn’t even eject. Lots of gas added with a can.

 

[loveha]

I think most here run 30 CAL cans on 5.56 rifles. But the amount you think is actually going to help is not a lot. If I was looking for a dedicated AR can, would probably pick up an OSS.

OSS HX-QD 762 FC KIT

The OSS HX-QD 7.62 is built with patented Flow-Through technology, it delivers 136-139 dB performance, is full-auto rated up to 5.56, and is cross-platform compatible up to .300 WM.

www.silencershop.com

 

[Longshot231]

Just about everyone puts a .30 cal can on their 5.56 guns. I would say most suppressor users are. It using 5.56 dedicated cans.

regardlessit will add a pretty good amount of back pressure unless you get something like an OSS can. My 11.5 runs like a top with my can attached. If I take the can off the bolt doesn’t even cycle enough to pick up another round. Half the time it doesn’t even eject. Lots of gas added with a can.

I got several OSS suppressors and they work as advertised. MY AR-15s don't have the carbon build up or gas blowing back in my face. They work just as well as if there wasn't anything screwed on the muzzle.

I'm doing another AR build and might even use the QB on a 224 Valkyrie. Yes, I know that might be stretching it but wanted to start asking the question anyway.

 

[Lunchbox27]

I run an Omega on my SBR, 18” SPR, and 22” Valk AR’s. All .224 cal.

All still have a ton of back pressure, all have adjustable gas blocks and run great.

 

[NighthawkCG]

SDN-6 on a 10.3" isn't bad for me. Sounds just fine too.

 

[Sniperwannabee]

Thunder Beast Arms Corporation [TBAC] | Products | DOMINUS-SR

 

[Mike_in_FL]

I've been thinking of putting a 30 caliber can on a 5.56mm AR-15 to avoid a lot of the back pressure and subsequent need for any weapon modification.

I was wondering if anyone has attempted this and what were your results?

I only have one can. I have a TBAC Ultra 9 .30. Mine attaches to either the CB brake or FH. I have the FH on a 10.5 BRN-180 which has a gas setting for suppressed and this can works great on it. I just shot it on my .260 this past weekend. I will probably buy more specific cans later but you can't beat this one for all that it will do well.

 

[Hateca]

I use my TBAC 338 can on bolt guns with 419 attachment for all kinds of calibers. I use a Sandman S .30 cal can on both AR15 and AR10 works great on both rifles.

 

[Strykervet]

I like dedicated cans. Back pressure and gas face is just something you gotta deal with on DI weapons.

Some cans have less back pressure than others, just do your homework if it's an issue. Like with Mk20 --FN won't warranty the rifle if a can is used IIRC due to this --but if you use the right one then there shouldn't be a problem. In this case, it's a Surefire can. I think they're known for lower back pressure?

But regarding DI AR's, yet to have one that didn't blow gas back to some degree. I use H335 powder and it's a bit dirty too but yields a true M855 for the most part. It's a trade off.

Sico Saker will be best of both worlds if you want a .30 can on a 5.56 --they make various end caps for 'em so you can get a .30 can and put a 5.56 end cap on it. Or one with a flash hider. Or some other implement. Not to mention a plethora of mounting options.

.30 cans are usually a bit louder for similar size, usually bigger in general and heavier, they have a deeper, throatier report vs. the higher pitch snap of a dedicated 5.56 can. A 5.56 dedicated can is worth it for size alone. I like the 5.56 Saker. Bomb proof and they're pretty cheap now but they used to be expensive when they first came out. Back pressure? Don't have a clue.

 

[Tacovrd]

I use my TBAC 338 can on bolt guns with 419 attachment for all kinds of calibers. I use a Sandman S .30 cal can on both AR15 and AR10 works great on both rifles.

How much less effective is the suppression using a .338 bored suppressor on something like a 6.5 chambered rifle? I kinda like the idea of this for versatility down the road regardless of what I'm shooting to give me options......

Also, are there any negatives on accuracy using something that is letting more gas out the front in terms of turbulence or something like that within the suppressor.

 

[Zak Smith]

How much less effective is the suppression using a .338 bored suppressor on something like a 6.5 chambered rifle?

The part everyone leaves out of the question is-- compared to what? A 338 Ultra will be quieter than anything 1.5x9" (ie an Ultra 9) because it is gigantic.

Also, are there any negatives on accuracy using something that is letting more gas out the front in terms of turbulence or something like that within the suppressor.

No, that all happens way after the bullet has left the building..

 

[vinniedelpino]

I use a tbac ultra 7 on my 14.5 mid with an H2 buffer. Its lighter than a lot of 5.56 specific cans from what I can tell. It makes for a seriously dirty gun, but I wouldn't swap it out for anything other than maybe the ultra 7 in 5.56.

 

[sirhrmechanic]

I have a hybrid and unless I am shooting .45, I just keep the 9mm/.380 cap on it for .30 and 5.56.

The difference in sound moderation going down to the smaller caps is negligible. ESP with supersonic ammo.

Sirhr

 

[Hateca]

How much less effective is the suppression using a .338 bored suppressor on something like a 6.5 chambered rifle? I kinda like the idea of this for versatility down the road regardless of what I'm shooting to give me options......

Also, are there any negatives on accuracy using something that is letting more gas out the front in terms of turbulence or something like that within the suppressor.

Some claim they can tell a difference but I can’t tell any distinguishable difference with my ears. And no there is no difference in accuracy. I also use a .45 can with my 9mm can’t tell a difference there either.

 

[Zak Smith]

In our R&D for the 6.5 and .30 cal Ultras, we found that changing just the endcap did basically nothing to suppression level.

 

[Tacovrd]

The part everyone leaves out of the question is-- compared to what?

I guess I was thinking compared to a dedicated can for the caliber being shot....

If it doesn't really matter with respect to degree or suppression or accuracy, and the only advantages are size/weight savings, then it seems advantageous to run say a .30 cal suppressor for anything .30, 6.5 or 5.56 unless I'm missing something else.

 

[Zak Smith]

Typically the 338's are larger than the .30 cal family, so it works out kind of different.

Also, even with a dedicated caliber-specific baffle stack, it doesn't necessarily guarantee it will be quieter. We don't make a 6mm Ultra 7 or 9 because the prototypes of them metered identical to the 6.5mm Ultras on .260REM/6.5CM. It just depends on a bunch of factors that can't always be predicted.

 

[WyCoShooter]

I have spent a fair amount of time reading on this same topic but have no experience first hand since all my cans are still in jail. The one thing for certain is with a gas cycled rifle there is no escape from gas blowback. It seems to me from what I have read that the more the gas is resisted and slowed down at the muzzle the more pressure is sent back to the ejection port. With a larger bore diameter can however there is more room for the gas to escape at the muzzle so you should in theory have less blowback. I have also read that because of this the decibel rating at the shooters ear tends to be better with .30 cal cans on a 5.56 but less effective at the muzzle. Just some thoughts on what I have read, I look forward to reading the opinions from the guys with a lot more experience on here.

 

[DCAN]

I've been thinking of putting a 30 caliber can on a 5.56mm AR-15 to avoid a lot of the back pressure and subsequent need for any weapon modification.

I was wondering if anyone has attempted this and what were your results?

Have done this several times on different guns. The gas blow back is still there. Went to a "gas buster" charging handle. That helped a lot. Tried a side charging handle and problem was gone. The one consistent issue if the gun is filthy dirty in short order. Adding weight to the bolt carrier to slow down the unlocking after firing has helped a little bit.
If there is a cure out there I can't wait to read how to do it!

 

[Longshot231]

Have done this several times on different guns. The gas blow back is still there. Went to a "gas buster" charging handle. That helped a lot. Tried a side charging handle and problem was gone. The one consistent issue if the gun is filthy dirty in short order. Adding weight to the bolt carrier to slow down the unlocking after firing has helped a little bit.
If there is a cure out there I can't wait to read how to do it!

How did you add weight to the BCG? Wouldn’t installing a heavier buffer and spring accomplish the same thing?

 

[DCAN]

How did you add weight to the BCG? Wouldn’t installing a heavier buffer and spring accomplish the same thing?

I purchased a weight system from David Tubbs web site. I checked the site several months ago and they were out of stock at that time. The heavier bolt carrier group delays the unlocking at the time of firing for just a fraction of a second. I really liked the way it changed the feel of the firing cycle. I believe Glen Zediker talks about the system in one of his books. I've heard there are other ways to add weight, just haven't looked into other options.
Not sure if the heavier buffer would do the same thing. I run a hydraulic in all my ar's. The springs I run are the ones sold by Tubbs. They last forever.

 

[DCAN]

Just checked Tubb's web site. Don't see the carrier weight system listed anymore. I can take some photos and measurements of the one I have and post those if you need.
Midway still has the system on the web site, just shows it as "Discontinued". Good pic's though. It's listed as "Tubb AR15 Bolt Carrier Weight System".

 

[Zatchmo]

JP makes different weight carriers, and has adjustable weights on the spring as well. Not a cheap way to go, but an option.

 

[DCAN]

JP stuff looks really nice!
Some quick research shows a heavier buffer spring and heavier buffer should have the same effect as the carrier weight system. Going to have to give that a try. Research also showed the CWS from Tubb has been gone since about 2017.

 

[Zak Smith]

For tuning, I recommend an adjustable gas block (I've been using Seekins), a JP SCS (you can change the 3 weights for tungsten weights to get add'l mass, and you can change the spring strengths), and then for small-block AR's either a full mass or lightened (but still steel) bolt carrier,depending on which way I am trying to go. In the big-frame AR's, JP has their VMOS (variable mass operating system) which uses the same style of weights as the gen2 SCS.

 

[DCAN]

For tuning, I recommend an adjustable gas block (I've been using Seekins), a JP SCS (you can change the 3 weights for tungsten weights to get add'l mass, and you can change the spring strengths), and then for small-block AR's either a full mass or lightened (but still steel) bolt carrier,depending on which way I am trying to go. In the big-frame AR's, JP has their VMOS (variable mass operating system) which uses the same style of weights as the gen2 SCS.

I haven't been keeping up with AR stuff for awhile. Noticing the reduced weight carriers seem to be the new cool thing. What's the reasoning behind going lighter? Just functioning?

 

[Longshot231]

Gentlemen,

You all are giving me great information. The problem is that I wanted to avoid any other modifications to the weapon. I was hoping a .30 caliber can on a 5.56mm AR would mitigate a lot of the backpressure.

I usually run the OSS suppressors on the gas guns. They work as advertised and they don't get any dirtier or have stuff blowing back at me than they do unsupressed.

I just hate waiting for the ATF machinery to spit out a tax stamp 10-12 months later when I can get a QB can in less than a couple of months.

And as I'm thinking of this, maybe a weapon modification is prudent to get the QB can and still avoid the long wait.

 

[Zak Smith]

I haven't been keeping up with AR stuff for awhile. Noticing the reduced weight carriers seem to be the new cool thing. What's the reasoning behind going lighter? Just functioning?

They're not really new. JP has had lightweight bolt carriers for close to 20 years or so? I've been shooting them in various configurations since '04. It just depends on the application.

The advantage is that in the force -> mass movement -> recoil spring compression -> bottoming out -> accelerating mass -> returning mass (stripping round and chambering it) cycle, you have more options if can control the force (ie amount of gas) and the amount of mass (BCG+buffer). 3Gunners have long used lightweight components to reduce to a minimum the amount of inertia transferred to the rifle and to reduce the cycle time so the gun seems to "shoot faster" (ie cycle faster). But if you think about it, as long as you can maintain enough inertia when the bolt carrier returns to reliably strip the next round, and the whole system stays in battery long enough while firing, if you reduce the BCG and/or buffer mass, you can then reduce the amount of gas required to operate the rifle. Now there's more to it, and the caliber and length of gas system comes into play, but that's the overview.

Here are some old AR15 threads in which we discuss it to some degree

Mapgpul Magazine Upgrade - Page 1 - AR15.COM

Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.

www.ar15.com

Pair of new MSTN 17" lightweight uppers (PICS) - AR15.COM

Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.

www.ar15.com

27 months with the MSTN Lightweight 17 - AR15.COM

Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.

www.ar15.com

ETA, in particular, here's a post from the first thread

Mapgpul Magazine Upgrade - Page 1 - AR15.COM

Firearm Discussion and Resources from AR-15, AK-47, Handguns and more! Buy, Sell, and Trade your Firearms and Gear.

www.ar15.com

 

[YammyMonkey]

A well made adjustable gas block goes a long way toward minimizing the blowback. I use SLR blocks on my suppressed 5.56 guns and the stick one on my Seekins 308, and the gas isn't bad at all with AE, Surefire & TBAC cans. And I shoot left handed.

The Radian SD and Geissele charging handles with the RTV silicone modification seem to help some too.

 

[hlee]

My ar15 must be broken. Granted that it is a 6.5 Grendel, but it doesn’t behave the way I was lead to believe it should. Without a can, it functions perfectly- locks open on empty, ejects at 3:30-4 in a pile less than 2’ in diameter. It does have an adjustable gas block. But when I add a suppressor, and don’t adjust the gas block, it locks open on empty and ejects at 3:30-4 in a pile less than 2’ in diameter. I’m not mag dumping, and shoot outside (club level PRS style events) but haven’t noticed any “gassiness.” The suppressor is a thunderchicken, if that helps. Thanks.