Suppressors Thoughts on Backpressure-- 5.56 RC2 vs Nomad-30

[Deepwoods]

I have 5.56 11.5" Triarc suppressor-only upper that currently has a Surefire brake and 556 RC2 suppressor, and I am pondering switching to a Xeno mounted Nomad-30 when it gets approved.

While I try to deconstruct Pew Science's very good test results, can anyone opine about the suppressors' relative back pressure? I shoot long guns lefty, and so am trying to minimize gas that escapes the ejection port. Baffle design, suppressor diameter/ volume, and .22 vs .30 cal exit holes...

This isn't a sustained high rate of fire upper, and for the purposes of this post, reducing port-gas is more important than sound suppression, flash, etc.

Triarc notes that low-flow suppressors (like OSS's design) don't provide enough pressure to cycle the bolt.

 

[alamo5000]

Here is a screen shot of the results of hearing tests Griffin did for an older version of their Recce 5 in a same day comparison test. The newer ECO baffles in the latest upgrade improve their model by a three DB at the ear over what is in this chart.

Regardless this is what a third party got using some expensive ass equipment for the RC2. It's actually really impressive. With a 30 cal can you will get about in the low 140 DB at the ear regardless of manufacturer (there are however exceptions). That is specifically referring to a 30 cal can being used for 5.56 in a 11.5" configuration. I say this because they published repeated comparison tests so that should be at least an indicator.

In short, the RC2 has my vote among the choices you presented. I don't own one but it seems like a really solid choice.

 

[Deepwoods]

Here is a screen shot of the results of hearing tests Griffin did for an older version of their Recce 5 in a same day comparison test. The newer ECO baffles in the latest upgrade improve their model by a three DB at the ear over what is in this chart.

Regardless this is what a third party got using some expensive ass equipment for the RC2. It's actually really impressive. With a 30 cal can you will get about in the low 140 DB at the ear regardless of manufacturer (there are however exceptions). That is specifically referring to a 30 cal can being used for 5.56 in a 11.5" configuration. I say this because they published repeated comparison tests so that should be at least an indicator.

In short, the RC2 has my vote among the choices you presented. I don't own one but it seems like a really solid choice.

I appreciate the chart. However, for the purposes of this thread, I am most interested in "gas coming back down the barrel and into my face." I don't know how to quantify that but I think this is byproduct of a can's back pressure...

 

[alamo5000]

I appreciate the chart. However, for the purposes of this thread, I am most interested in "gas coming back down the barrel and into my face." I don't know how to quantify that but I think this is byproduct of a can's back pressure...

I understand, and it is all related.

At least you aren't doing something dumb like trying to tune your gas block.

There are some cans that restrict gas flow so much that they increase gas in the face by a lot. On a bolt gun that kind of constriction is ok, but on a gas gun not so much.

Ammo, and particularly powder choice is IMO a huge factor here. Nothing at all to do with the can per se. Gassy dirty powders are much more prone to gas out a shooter for obvious reasons.

In my opinion there isn't a way to totally eliminate it, but rather just ways to make it a little bit less.

 

[Gasgun]

What are you trying to accomplish with a change to the Nomad? Your post doesn’t state your objective.
Is it greater sound reduction? Lower back pressure?
I shoot lefty and have the SureFire mounted on uppers with Colt barrels of 10.3”, 11.5” and 14.5” length.
All have standard gas ports for their length. No adjustable gas blocks, heavy buffers or any other such fuckery.
I have zero complaints about the gas out of the ejection port. They all run 100%.
I imagine that with a dedicated suppressed upper like your Triarc that blowback with the RC2 would just about be a non issue.
If you’re looking for greater sound reduction, I think that chasing decibels on a short barreled AR pattern rifle is a waste of time.
I have owned 5.56 and .30 cans from several manufacturers over a couple decades and shot them alongside others’ cans from other manufacturers. Between action noise and sonic crack from the bullets, a few decibels sound reduction from the suppressor is unnoticeable.
If you’ve already bought the Nomad, mount it up and see how it compares. I would be interested to hear about your experience with it.
I doubt that it’s going to be a drastic improvement over the SureFire, though.

 

[Deepwoods]

Thanks Gasgun,

Buried in the middle of the OP, I note minimizing ejection-port gas, and which options--the current SF or the pending DA--which is likely to have less gas out of the ejection port. While not offensive, less gas is better. I understand that a precise/ scientific answer for this may be elusive; I'm just interested in opinions.

I'm less concerned about sound reduction as with this rifle, I've got ear pro on.