Looking for help with lower power .223 loads

Well, between night vision and a suppressed AR, I want to load some lower velocity 223 loads. Went shooting the other night and it was pretty much magical, except for listening to the supersonic crack sound light a fighter jet going over. But even that was pretty cool.

ive researched subsonic and don't want to deal with it for 223. I have a .22 suppressed that shoots subsonic and cycles the gun. I'm not interested in a single shot AR

basically I was curious if you guys have done any load testing for lower power, and lower noise that will reliably cycle an AR. 16". Can be either 1/9 or 1/7 twist as I have both.

and also, is it even worth it? I'm sure I will still hear the supersonic crack traveling after I shoot. The suppressor is definitely quiet enough even shooting standard m193 rounds. But I think it could stand to be a but more quiet and possibly cut down on the supersonic noise as well.

let me know your thoughts

I think Kazoo played with low power .223 and the results where less than spectacular... Is your can 223 or 30 cal? .30 cal begs to have some blackout ran through it

Repost.

Seriously, I seem to remember a thread about this somewhere here. Although, it might have actually been about subsonic loads.

Or I could be thinking of something else.

Who knows.

I've got nothing for you I guess.

[Beer]

Yeah it was Kazoo who tried this and I think the result was to go with 300 blkout for suppressed.

I found his thread on subsonic loads but that's not what I'm after. I still want supersonic, just at lower velocities, and I wasn't sure what FPS value and bullet weight to try out so I figured I'd see if there was anyone here who tried it. And if it will make a big difference with a suppressor and the supersonic sound that can be heard after the shot.
i don't have a chrono yet so was mostly looking for load data to start with.

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Originally Posted by DFBrews

I think Kazoo played with low power .223 and the results where less than spectacular... Is your can 223 or 30 cal? .30 cal begs to have some blackout ran through it

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Unfortunately 223. I kick myself a little but for not just getting a .30 can.

guess I'll have to get another one...such a shame.[Coffee]

Once you hit supersonic speeds, will a projectile of that size/mass make that much of a difference in sound intensity within that range? I don't know the science behind it, so I am just asking.

ETA: SS crack of .223 projo at threshhold of sub/super vs same at 3000-3200FPS ?

So this brings up the question of whether all super sonic cracks are made equal. Is that pretty much what your trying to find out?

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Originally Posted by Irving

So this brings up the question of whether all super sonic cracks are made equal. Is that pretty much what your trying to find out?

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I guess that is pretty much it. I know the lower pressure/FPS of the projectile will produce a less decibels.

but the supersonic crack has me curious.

I suppose if you knew some dudes with different suppressed guns you could just have them run different stuff like .308 vs. .270 or something to save you time in the reloading room. Interested to hear what you find.

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.

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.

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

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Originally Posted by 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.

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

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

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

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.

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.

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.

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.

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Originally Posted by 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.

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

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Originally Posted by sniper7

Well, between night vision and a suppressed AR, I want to load some lower velocity 223 loads. Went shooting the other night and it was pretty much magical, except for listening to the supersonic crack sound light a fighter jet going over. But even that was pretty cool.

ive researched subsonic and don't want to deal with it for 223. I have a .22 suppressed that shoots subsonic and cycles the gun. I'm not interested in a single shot AR

basically I was curious if you guys have done any load testing for lower power, and lower noise that will reliably cycle an AR. 16". Can be either 1/9 or 1/7 twist as I have both.

and also, is it even worth it? I'm sure I will still hear the supersonic crack traveling after I shoot. The suppressor is definitely quiet enough even shooting standard m193 rounds. But I think it could stand to be a but more quiet and possibly cut down on the supersonic noise as well.

let me know your thoughts

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A 75gr bullet with H322 out of your 1:7 barrel should drop you into the 2500-2600fps range w/out any cycling issues. H322 is one of the fastest burning powders for the 223 and it may accomplish your goal. Start at 20gr and see if you can drop it from there and/or adjust for accuracy. I will ask a friend of mine who loads for his suppressed 223.

EDIT: I talked to my friend, who suppresses his 223 (among others). He doesn't feel as though this will accomplish much if anything