Suppressors Thunder Beast Dominus, Dominus-K and 338 SR on 18" 308 SP10

[TBACRAY]

Dominus K
MR- 146.1, 145.2, 143.7, 144.6, 143.3 Avg- 144.6
ML- 144.5, 144.2, 141.3, 143.9, 141.3 Avg- 143.0
MR/ML Avg- 143.8
SE- 139.3, 139.9, 138.9, 138.3, 138.0 Avg- 138.9

Dominus
MR- 141.2, 140.7, 140.2, 142.4, 140.3 Avg- 141.0
ML- 141.6, 139.0, 141.5, 140.6, 140.4 Avg- 140.6
MR/ML Avg- 140.8
SE- 139.1, 139.5, 140.5, 139.9, 140.9 Avg- 140

338SR
MR- 135.4, 134.5, 135.9, 136.5, 136.2 Avg- 135.7
ML- 134.8, 134.0, 134.4, 135.0, 135.2 Avg- 134.7
MR/ML Avg- 135.2
SE- 141.5, 141.9, 140.9, 141.3, 140.9 Avg- 141.3

 

[BikePilot]

The K is the quietest at the shooters ear? Is that due to less back pressure?

 

[Zak Smith]

Yes

 

[Zak Smith]

The lesson I take away from this data is, "Put a Dominus-K-SR on all gas guns." Pending more data for categorical statement, but as a general rule..

 

[BikePilot]

Just curious, were these done with the same gas setting or was the gas adjusted for each one?

 

[SDet]

Just curious, were these done with the same gas setting or was the gas adjusted for each one?

Same gas

 

[BikePilot]

Same gas

Thanks, I wonder if the results would change dramatically with a gas block adjusted for each one.

 

[Sniperwannabee]

The lesson I take away from this data is, "Put a Dominus-K-SR on all gas guns." Pending more data for categorical statement, but as a general rule..

no matter what caliber 300AAC or 556? SE is all that matters for most

 

[Zak Smith]

Thanks, I wonder if the results would change dramatically with a gas block adjusted for each one.

There will be a change, not sure if it will be dramatic until we do it. In the past, gas changes have accounted for up to 8 dB @ SE. It depends on the setup.

 

[Zak Smith]

no matter what caliber 300AAC or 556? SE is all that matters for most

It appears so far that it holds for 308 and 556. I suspect it will for 300 BO based on the G2 U5 vs U7 numbers, but I don't have that data yet.

 

[samb300]

@Zak Smith does less back pressure on the Dominus-K-SR definitively mean less gas in the face? I shoot lefty, and my Dominus-K on order is earmarked specifically for my SCAR 17 (currently a 16", thinking about a 13" SBR). Even tuning the gas control screw size, it's still really gassy with my SiCo Omega.

Should I consider switching to the Dominus-K for this application?

 

[Zak Smith]

In general, less backpressure should mean less gas in the face. At present we don't have a way to directly measure backpressure, let alone other cans' backpressure, so I hesitate to promise it would be different enough in your case. I am pretty sure it would, but that's just my own speculation.

Another thing about backpressure, is that gun design and setup can make a huge difference in the amount of gas in the face. On an AR15/AR10 pattern rifle, my strategy is to go with the longest possible gas system for the given barrel length, and then tune the adjustable gas block (analog or "many click" types), starting with no gas, until the bolt just barely locks back on an empty mag when shot. If you want more margin, add a tiny bit more gas.

If you need the gun to function without the suppressor, do this but without the suppressor. When you put the can on, it will have increased back pressure (compared to paragraph above) but it'll still have less than it would have had without adjustment.

Basic rules of thumb for AR-15's chambered in 223/556:
* 17" and longer barrels (16" for suppressed only) should not have a gas system shorter than: RIFLE
* 16" barrels should not have a gas system shorter than: INTERMEDIATE (ie, Vltor/Noveske Intermediate)
* 13.7-14.5" barrels should not have a gas system shorter than: MIDLENGTH
* 10-12.5" should not have a gas system shorter than: CARBINE

I don't have enough time testing a SCAR to give good guidance on it, other than their threads seem to always lack a proper shoulder.

 

[samb300]

In general, less backpressure should mean less gas in the face. At present we don't have a way to directly measure backpressure, let alone other cans' backpressure, so I hesitate to promise it would be different enough in your case. I am pretty sure it would, but that's just my own speculation.

Another thing about backpressure, is that gun design and setup can make a huge difference in the amount of gas in the face. On an AR15/AR10 pattern rifle, my strategy is to go with the longest possible gas system for the given barrel length, and then tune the adjustable gas block (analog or "many click" types), starting with no gas, until the bolt just barely locks back on an empty mag when shot. If you want more margin, add a tiny bit more gas.

If you need the gun to function without the suppressor, do this but without the suppressor. When you put the can on, it will have increased back pressure (compared to paragraph above) but it'll still have less than it would have had without adjustment.

Basic rules of thumb for AR-15's chambered in 223/556:
* 17" and longer barrels (16" for suppressed only) should not have a gas system shorter than: RIFLE
* 16" barrels should not have a gas system shorter than: INTERMEDIATE (ie, Vltor/Noveske Intermediate)
* 13.7-14.5" barrels should not have a gas system shorter than: MIDLENGTH
* 10-12.5" should not have a gas system shorter than: CARBINE

I don't have enough time testing a SCAR to give good guidance on it, other than their threads seem to always lack a proper shoulder.

Thanks. I have an 18" AR with a GemTech adjustable bolt carrier group and that greatly helps the gas blowback since it does not have an adjustable gas block.

The SCAR is a bit of a beast, and has a 2-setting gas block for suppressed and non-suppressed. I should probably play around with it some more; the only way to tune it is replace the gas port screws with a different aperture size and test exactly like you described. The last time I shot it with the SiCo Omega it was offensively gassy in my face, even with a reduced gas port screw...I'd definitely sacrifice some dB reduction for reducing that gas.

I wonder if the 13" SCAR SBR will be any gassier than the 16" considering they have the exact same length gas system...

I use a Parker Mountain Machine "shoulder ring" on my SCAR and the alignment rod shows I'm good with the Omega using an un-timed flash hider.

 

[Zak Smith]

My guess is that the SBR would be less gassy because there is less barrel past the port.
The "louder at the muzzle" suppressor should, all other things equal, be quieter at the SE, at least this it he general rule we've found with gas guns.
And FWIW, basically all my gas guns are going to shoot the Dominus-K-SR or the Ultra 5.