SBR running super hot with silencer

[seemankyle]

I finally received my stamps for my SBR I built and my SilencerCo Specwar.

SBR Specs:
Anderson Lower
Aero Upper
Aero NiB BCG
7.5" Barrel
JP Adjustable Gas Block
223/556

After getting my gas block adjusted to cycle my rounds, I really started playing and around and testing out the SBR and silencer to see if I had any malfunctions with the gas block adjustments during rapid fire.
Now I realized I'm running a short setup and that guns are going to get hot, but is it normal after running approximately 60 rounds thru the gun for the gun to become too hot to hold my hand guard and even hold where the upper joins the hand guard?

Here's a link to my gun pic:
https://photos.app.goo.gl/U4PDFTs81yP33r4h7

[Aaron]

I finally received my stamps for my SBR I built and my SilencerCo Specwar.

SBR Specs:
Anderson Lower
Aero Upper
Aero NiB BCG
7.5" Barrel
JP Adjustable Gas Block
223/556

After getting my gas block adjusted to cycle my rounds, I really started playing and around and testing out the SBR and silencer to see if I had any malfunctions with the gas block adjustments during rapid fire.
Now I realized I'm running a short setup and that guns are going to get hot, but is it normal after running approximately 60 rounds thru the gun for the gun to become too hot to hold my hand guard and even hold where the upper joins the hand guard?

Here's a link to my gun pic:
https://photos.app.goo.gl/U4PDFTs81yP33r4h7

It doesn't surprise me that it is getting very hot with a barrel that short. Especially after a couple mag dumps. Have you checked your head space?

Aaron

[T-Rex]

Where is your brass landing, once ejected, in relation to the bore centerline?
What ammo are you using?
Does the bolt lock back on empty mag (last round hold open)?
What barrel? Specifically profile and thickness.

[John A.]

Yeah, 223 will get hot.

https://www.youtube.com/watch?v=BczhT1ByrXA

[seemankyle]

I finally received my stamps for my SBR I built and my SilencerCo Specwar.

SBR Specs:
Anderson Lower
Aero Upper
Aero NiB BCG
7.5" Barrel
JP Adjustable Gas Block
223/556

After getting my gas block adjusted to cycle my rounds, I really started playing and around and testing out the SBR and silencer to see if I had any malfunctions with the gas block adjustments during rapid fire.
Now I realized I'm running a short setup and that guns are going to get hot, but is it normal after running approximately 60 rounds thru the gun for the gun to become too hot to hold my hand guard and even hold where the upper joins the hand guard?

Here's a link to my gun pic:
https://photos.app.goo.gl/U4PDFTs81yP33r4h7

It doesn't surprise me that it is getting very hot with a barrel that short. Especially after a couple mag dumps. Have you checked your head space?

Aaron

Yes, my head space is good.

[seemankyle]

Where is your brass landing, once ejected, in relation to the bore centerline?
What ammo are you using?
Does the bolt lock back on empty mag (last round hold open)?
What barrel? Specifically profile and thickness.

I don't recall where brass was landing, I'll check when I go back out to shoot over memorial day weekend.
Ammo was various, Federal .223 brass, winchester .223 brass and a few Tul Ammo Steel.
The bolt locked back all but one time and that was during when I was adjusting the gas block if I recall.
This is the only info on the barrel I have from the online receipt when I purchased, sorry if that doesn't help: AR15 5.56 223 NATO 7.5 M4 BARREL 1-7 CARBINE AR-15

[mbogo]

Could your gas block be leaking?

Consider removing the handguard(s) and putting one course of masking tape around the gas block. Fire one round and look for telltale evidence of a leak.

mbogo

[CanOfWhooppass]

The Specwar has a good amount of volume, so after the bullet leaves the can, it is holding a lot of high pressure fire ball.
If the bolt opens before pressure drops that heat comes back down the barrel into the action. How dirty is it running and is the reciever as hot as the handguard?
Did you adjust the gas block for silencer on or off? If for suppresdor off, try turning it down and see how it runs this way.
If it is much better, the problem may be that the difference in back pressure is dramatic due to the short barrel. If so you may want to leave it that way or try something like the bootleg adjustable bolt carrier that let's you adjust gas block for SBR and bolt for suppresdor use.
Barrels that short are finicky. I find my 5.56 10.3" prefers my 7.62 Saker over a 5.56 Saker because of less back pressure.

[seemankyle]

The Specwar has a good amount of volume, so after the bullet leaves the can, it is holding a lot of high pressure fire ball.
If the bolt opens before pressure drops that heat comes back down the barrel into the action. How dirty is it running and is the reciever as hot as the handguard?
Did you adjust the gas block for silencer on or off? If for suppresdor off, try turning it down and see how it runs this way.
If it is much better, the problem may be that the difference in back pressure is dramatic due to the short barrel. If so you may want to leave it that way or try something like the bootleg adjustable bolt carrier that let's you adjust gas block for SBR and bolt for suppresdor use.
Barrels that short are finicky. I find my 5.56 10.3" prefers my 7.62 Saker over a 5.56 Saker because of less back pressure.

I could not believe how dirty the gun ran, I'd never seen a gun so dirty for so few rounds.

Yes, eventually the receiver become as near as hot as the handguard as I couldn't hold it by the mag-well without starting to burn my index finger.

I adjusted the gas block for the silencer on. I do know when I shot the rifle for the first time a week before I received my silencer that it didn't run this dirty, however, I didn't shoot near as many rounds as I did with the silencer.

Thanks for your input!

[CanOfWhooppass]

I would adjust it again, a new build can be pushing more gas after some shooting as areas get opened by that hot jet of gas. Kind of surprised it got that dirty and didn't start to short stroke. It should just lock back on an empty magazine.
If you brass is falling around 3 O'clock spitting distance it is good.
If that is good I'd try a tape test as mentioned, let it cool so the tape doesn't become a permanent addition to the rifle and hit every spot that could leak. Gas block, gas tube both ends and around back of can. If you are leaking around your mount, with your handguard that close, could do it also.
It's a little late now, but advice if you were still planning the build would be go 300 blackout if you want that short, or go 10.5-12.5 if you are set on 5.56.
Barrel swap might be easiest fix if she keeps fighting you.

[gsyoung54]

The Specwar has a good amount of volume, so after the bullet leaves the can, it is holding a lot of high pressure fire ball.
If the bolt opens before pressure drops that heat comes back down the barrel into the action. How dirty is it running and is the reciever as hot as the handguard?
Did you adjust the gas block for silencer on or off? If for suppresdor off, try turning it down and see how it runs this way.
If it is much better, the problem may be that the difference in back pressure is dramatic due to the short barrel. If so you may want to leave it that way or try something like the bootleg adjustable bolt carrier that let's you adjust gas block for SBR and bolt for suppresdor use.
Barrels that short are finicky. I find my 5.56 10.3" prefers my 7.62 Saker over a 5.56 Saker because of less back pressure.

I don't think the Bootleg bolt carrier will like being fired fast or full auto or slide fire or double magic triggers... I think they state that so you may want to spend the extra bucks and get a Gemtech. I run mine fast all the time with no problems, and having the Gemtech plus the Odinworks adjustable gas blocks gives me a lot of possibilities to play with. I do have a few JP gas blocks too, they make one built into an A front sight that works pretty well but used two set screws instead of the one click adjustable Odin one. I do like the way Bootleg puts the adjustment part right in view where I have to take the Gemtech out every time to set it... not a big deal but i do wish they had done it like the Bootleg.

[hardcase]

Typical length for the manufacturer to do any warranty work is minimum of 8", some 9" with 5.56/.223. 7.5" is really to short for routine rapid fire, mag dumps with a can. Might be prudent to check with the can manufacturer to see what they recommend.