300BLK Reloads vs. Factory Suppressor Perfomance

[mikeF35]

I recently shot factory subs through my rifle with a supressor, followed up by some reloads. My perception is the reloads are much louder than the factory rounds, as in I could comfortably shoot the factory without ear pro, but not very comfortable with the reloads.

Setup: 10.5" barrel, pistol-length gas system, Dead Air Wolfman suppressor.
Factory ammo: S&B 200gr subsonic (I wish I had all the cartridge data, but I foolishly shot it all without getting data)
Reloads: I did some work without the suppressor to dial in the load, then just shot my "final" recipe through the suppressor. That recipe is...
Berry's 220gr SP, LC brass, CCI small rifle primer, A1680 11.7gr, 2.26" COAL, avg muzzle velocity 947 FPS w/ max 994 (measured ~1 ft from the muzzle)

As far as performance, the reloads are great; I would change nothing about this load outside of the sound volume. The Wolfman is exceptional with the S&B cartridges - amazing how quiet it is, so I know the suppressor is not to be blamed here.

Before this, I thought velocity was the only thing you had to worry about when building a load for supressors, but now I think I'm wrong about that. So hopefully some smart people out there can help me understand what it is about my reloads that make such a substantial difference (negatively) in the perceived sound level of my setup. I realize we're not exactly comparing apples to apples (220gr vs. 200gr for starters), but I'd like to think there are 220gr sub recipes out there that will be just as awesomely quiet as the factory rounds with the suppressor. Thanks!

[ReadyAimDuck]

Different powders are going to generate different sound levels even with the same bullet. I'm not 100% sure of the science behind it so I will let others chime in on that. Its enough for me to know that burn rates and pressure has a bit to do with it, and it took some experimenting to find the quietest powder for subs. You may end up with a compromise between sound level, accuracy, and cleanliness depending on what is important to you and your particular application.

[mikeF35]

That's a good point. Do you (or anyone else?) have recommendations on powders that yield best sound suppression? I'm not shooting animals/people with these loads, just range fun; I'm not concerned with terminal velocity/energy, and accuracy just has to be good enough to hit targets 100 yds and in.

[dellet]

This might interest you.
viewtopic.php?f=128&t=98869

Basically the faster the powder, the quieter it will be. There are a lot of other factors. Gas system length, bullet weight barrel length. But in general running the fasted powder you can, and have reliable cycling, will be the quietest and cleanest.

[30plinker]

TL;DR - burning more slower powder generates more gas volume than burning less, faster burning powder, and the more gas a suppressor has to handle, the louder it will be.

The longer version -

Pressure generation and gas amounts will affect what your can sounds like

Pressure generation is affected by how quick the powder burns and the amount of gas it generates when it burns. A faster burning powder will generate less gas over all (you are using a fraction of the weight of the slower powder), but it will do so earlier in the cycle and so it will generate similar peak pressures as a slower burning powder that will need to produce more gas volume to reach the same pressures later in the cycle (think about volume difference with bullet in case, vs. two or three inches down barrel vs 8 or 9 inches down barrel)

Your suppressor works by controlling the gas release/expansion from the muzzle and slowing it down but it only has however many cubic units of volume inside of itself to do that with. This is why for a given design a larger suppressor will be quieter - it simply has more space to hold the gasses it is controlling.