Suppressors Sub-caliber suppression levels for QD/BA cans

[BurnOut]

I have a feeling that this question has been asked before, but has anyone checked for differences in suppression levels when shooting sub-caliber rounds (as compared to the can) *through a caliber-specific brake-mount*?

For example, let's say that you're shooting .223 through a 30-caliber can, and you have two brake-mounts from which to choose... one designed for use with .223 rounds, and one designed for use with 30-caliber rounds (the difference, for the sake of this discussion, being the diameter of the bore in the brake-mount). Are suppression levels going to be different depending upon which brake-mount is chosen?

My thinking is that the smaller bore of the .223 brake-mount will offer less clearance between the bullet and the brake, thereby "stripping off" more of the gasses surrounding the bullet than would the 30-caliber brake-mount, which in turn could affect the amount of those gasses channeled in to the first (maybe second? depending on how far in to the can the brake-mount extends) expansion chamber within the can... which in turn could affect suppression levels.

Might there be something to this, or am I over thinking it?

 

[RollingThunder51]

BO, a thoughtful question.
If we set aside the great variations to be found in the QD brakes designs themselves, the can's entry galley, the design of the blast baffle and its primary chamber, the variations in the equally critical secondary chamber/baffle, the short answer is that impact on dB is immaterial and may actually increase the potential for frp and temp dwell.
The issue is the actual effective disruption provided by any port now closed off to the outer environment and the real effectiveness of the final last brake facing that redirects the gas jet towards those blocked ports. There is no effect, except potential hot spotting and potential carbon buildup, again design dependent. More trapped 02 near unspent powder (first round) and the potential for hot spotting and the residual heat retention (dwell) can increase dB for subsequent shots quickly. If one was to actively manage their brake components, the best possible outcome in regard to dB would be to remove any ported brake and thread on a port-less tight bore tolerance QD transition piece. This would allow for full gas jet impact on the disruptor facing to be realized at the initial blast baffle. A potential exception would be the rare case of early reflex cans that used a brake for active suppression, there sub-caliber rounds might provide superior suppression if the brake was swapped out and had tight tolerances. There the sub caliber gasses benefit from the increased rear chamber volume, all working to your advantage.

 

[BurnOut]

RT51- I appreciate your response. If I understand you correctly, you're essentially saying that running ANY brake-mount has the potential to disrupt the gas flow through the suppressor, diverting more gas in to the 1st/2nd chambers than the design (of the can its self) was intended to handle, leading to poor heat distribution (specifically, the 1st/2nd chamber being abnormally hot). This, in exchange for what would likely be an unnoticeable difference in sound attenuation at best, and at worst, marginally worse sound suppression (especially on the first shot).

Is my understanding correct, or do I need to have another go at it?

 

[jasonfaz]

In short, a high quality 5.56 can will suppress 5.56 better than the best .308 can. It gets pretty close however, if you can change a 30 cal end cap to a .223. Even then you're giving up multiple benefits of a dedicated 5.56 can provides you.

 

[krw]

I shoot my YHM QD ti 30cal can on my bolt 223. I am pleased with results but am shopping for a dedicated 223 can as I shoot 223 more than all the rest of my stuff put together.

 

[RollingThunder51]

My fault for not making it clear enough.

"that running ANY brake-mount has the potential to disrupt the gas flow through the suppressor"
No, the disruption provided by a QD brake with its ports closed off to the external environment is so minimal as to not matter in regard to suppression. The exception can be some reflex designs.

"diverting more gas in to the 1st/2nd chambers than the design (of the can its self) was intended to handle,"
No, the brake does not divert any more of anything into a standard blast can, it can only potentially and marginally disrupt the gas flow prior to reaching the can.
Again, with some reflex designs, sub calibers that can divert gas efficiently reward will find the additional volume of the larger caliber can an advantage.

"leading to poor heat distribution"
This is the only potential effect that the brake can provide. A small dwell at the brake with poor thermal radiant attributes. The brake can also potentially cause higher frp.

" would likely be an unnoticeable difference in sound attenuation at best, and at worst, marginally worse sound suppression (especially on the first shot)."
Correct

Suppressing .223 in general is difficult, it is the can most likely to disappoint. Can designs today, with the current trend towards "mini" only make that situation worse.
The tail jet gas is problem and stripping it is hard to do in the .223.
One wants:

1. Fully featured facing on conical baffles,
2. More volume means much better performance, especially with higher firing schedules.
3. Staged and timed baffles (with core bore diversion cuts) and staged chambers

Changing an end cap requires a thorough understanding of the law and that last stage is the poorest place to do it.
A good rule to remember is that a properly designed suppressor for the exact caliber used will always outperform shooting through a higher caliber can.

 

[jasonfaz]

Very thorough, spot on response.

To clarify, rather than suggesting one might consider changing the caliber of one's suppressor (which is illegal), I was referring to the 7.62 Saker when I mentioned end cap changes. To rollingthunder's point, I'd agree that's a really bad spot to forego fully welded components to incorporate a much weaker design that may be perceived to be effective, yet still won't get suppression levels down to where the top 5.56 cans will.

 

[jasonfaz]

My fault for not making it clear enough.

"that running ANY brake-mount has the potential to disrupt the gas flow through the suppressor"
No, the disruption provided by a QD brake with its ports closed off to the external environment is so minimal as to not matter in regard to suppression. The exception can be some reflex designs.

"diverting more gas in to the 1st/2nd chambers than the design (of the can its self) was intended to handle,"
No, the brake does not divert any more of anything into a standard blast can, it can only potentially and marginally disrupt the gas flow prior to reaching the can.
Again, with some reflex designs, sub calibers that can divert gas efficiently reward will find the additional volume of the larger caliber can an advantage.

"leading to poor heat distribution"
This is the only potential effect that the brake can provide. A small dwell at the brake with poor thermal radiant attributes. The brake can also potentially cause higher frp.

" would likely be an unnoticeable difference in sound attenuation at best, and at worst, marginally worse sound suppression (especially on the first shot)."
Correct

Suppressing .223 in general is difficult, it is the can most likely to disappoint. Can designs today, with the current trend towards "mini" only make that situation worse.
The tail jet gas is problem and stripping it is hard to do in the .223.
One wants:

1. Fully featured facing on conical baffles,
2. More volume means much better performance, especially with higher firing schedules.
3. Staged and timed baffles (with core bore diversion cuts) and staged chambers

Changing an end cap requires a thorough understanding of the law and that last stage is the poorest place to do it.
A good rule to remember is that a properly designed suppressor for the exact caliber used will always outperform shooting through a higher caliber can.

Rollingthunder51,
Have you had the opportunity to study some of the most effective, patented baffle designs used in 5.56 cans currently on the market? If so, I'd be interested in your thoughts around those specific stack's design advantages and what measurable value can be had as a result. Any guidance would be very much appreciated!