Looking for help with lower power .223 loads

[crays]

Basically. Is the SS crack of a given projectile (55g FMJ) noticibly different at 1200FPS and 3000FPS, for argument's sake?

ETA: googlefu says supersonic is ~1125FPS at 68° in dry air at sea level. I've never seen dry air at sea level, at any temp...lol.

[ray1970]

Pulling targets in the pits at CMP matches years ago I never could hear a difference when the bullets whizzed overhead. To me the 5.56 stuff and the 30-06 stuff sounded the same flying over.

Of of course my hearing isn't much better than my vision. For whatever that's worth.

[crays]

Or will the sound level be the same, but take longer to hear (at 3000FPS)?

[crays]

Pulling targets in the pits at CMP matches years ago I never could hear a difference when the bullets whizzed overhead. To me the 5.56 stuff and the 30-06 stuff sounded the same flying over.

Of of course my hearing isn't much better than my vision. For whatever that's worth.

What's that? I couldn't quite hear what you saw?

ETA: I think bullets whizzing overhead is an entirely different discussion.

[Great-Kazoo]

Reliable in reduced loads are not going to happen, consistently. Hoser has some .308 sub loads see what he suggest. . For minimal Crack you need to be under 11-1200 FPS. A brief web search will give you some help.
. My halo and or AAC (halo is quieter) using standard factory or hand loads sound wise, does not produce this sonic crack at all. Sure it's fun to experiment load development wise, but....YMMV

[sniper7]

I'll try some out and see what I can come up with if there is a noticeable difference. I was shooting flat land, near river bottom and could hear the supersonic crack for probably 2-3 seconds after the shot.

[crays]

If your projectile travels faster than the speed of sound, it will produce a sonic crack. Unless the suppessor is impeding the velocity of the projectile, the crack is still there.

ETA: The suppressor is manipulating the report caused by the gases exiting the muzzle, not the sonic crack of a supersonic bullet. That is why sub-sonic round suppress so well. Lower gas pressures to deal with at the muzzle, and no sonic crack from the projectile.

[MarkCO]

I have been playing with reduced loads in .223 ARs, basically 22Mag levels. Yes, the noise is significantly reduced, but the sonic crack is still the same. 50 grain slugs at 2300 fps through an AR are kind of cool, but a lot of set-up and effort to get there if you are just plinking. You need a fast powder, empty buffer, reduced power spring. excellent gas block seal, and even then, you might have to open the gas port.

[Tim K]

Going back to fluid dynamics courses back in the 80's, I think the crack is more a function of projectile size than speed. A cannon round going the same speed as a bullet is going to make more noise because the shock wave is displacing more air around it. Probably a function of diameter, not weight.

I don't think speed will affect the sound level, but hell, those classes were 30 years ago. Plus I drink. And have kids.

[Great-Kazoo]

Going back to fluid dynamics courses back in the 80's, I think the crack is more a function of projectile size than speed. A cannon round going the same speed as a bullet is going to make more noise because the shock wave is displacing more air around it. Probably a function of diameter, not weight.

I don't think speed will affect the sound level, but hell, those classes were 30 years ago. Plus I drink. And have kids.

So are you placing blame age, alcohol issues , kids, or all 3 ?