What is the quietest suppressed centerfire round that is still fairly lethal and accurate out to 100 yards.

Lethal = lets keep it to a basic headshot
Accurate = fairly flat trajectory and repeatable shot placement
Quiet = overall sound, at the muzzle and at the target

Where is the sweet spot? Obviously a 25acp would be quiet but not very lethal and would require a major holdover.

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Suppressed .38 Special is hilariously quiet out of rifle.

Following out of curiosity.
I'd think a non semi-auto would lend to being quieter.
I remember someone here mentioning a suppressed 30-30, not sure if there's a subsonic 30-30 load.

quote:

Originally posted by P250UA5:
Following out of curiosity.
I'd think a non semi-auto would lend to being quieter.
I remember someone here mentioning a suppressed 30-30, not sure if there's a subsonic 30-30 load.

https://www.hornady.com/ammuni...-win-175-gr-sub-x#!/


There is also a subsonic .308 round. Would these all be on par with the 300 blackout ballistics?

I'm not a suppressor designer but I would think you want to minimize the amount of gas you have to manage so all these big rifle cased rounds seem unlikely to be winners. and again since you have to accelerate with more powder I think you want the lightest possible projectile that one would consider lethal. P220 Smudge is heading I would think in the right direction. A subsonic small bore center fire pistol cartridge. If the original suggested .25acp doesn't do it, them maybe the next step up might in .32acp. or .32 S&W. Or maybe .30 luger loaded to subsonic. Or maybe 5.45x18, tiny case subsonic light bullet... Depends on how far out of the mainstream you want to get and what you consider an acceptable threshold on lethal at 100y.

I find 300 blackout with the 220 grain bullets is pretty good, but are we talking only pistol rounds?

Nothing about the OP specified anything about the type of rounds other than center fire and some (unspecified) level of lethality at 100y. Some (myself included) have hypothesized that a pistol round is likely to be quieter than a rifle round. I said that because even small cans make .22lr very quiet and even large cans don't make .50bmg quiet so I theorized that there is some kind of linear relationship. That may or may not be true, its just my theory. And in the few situations I can say personally a 9mm hush round sure sounds quieter to me than a .300Blk subsonic round. But I don't have testing equipment and as we all know the ear is not a very sensitive instrument. Finding a bolt action 9mm sub test and a bolt .300bo test would probably answer the question, but I've not the time to search. Or some other small pistol round bolt results....300bo results are easy to find.

This question is not that simple. lol
I'm assuming you mean standard "off the shelf" cartridges and not ones made specifically for the task of being quiet.

I’ve seen a delisle suppressed carbine (45ACP) shot and it’s Hollywood quiet. I dunno the ballistics of a 230 grain fmj at 100 yds but I’d bet it would kill a human.

My buddy has a Handi rifle in 44 that’s suppressed and we loaded some rounds to be subsonic and they were stupid quiet and accurate. The round we loaded up was a 240 gr JHP.

A bolt gun or break action will be quieter than a semi auto, if you can get a semiautomatic to cycle.

I have a 300 BO in an AR pistol and a can and it’s quiet, but also loud as it has that semiautomatic pop from the ejection port, when it’s fired.

If your looking to shoot sentry’s, than a bolt gun is the way to go in my opinion.

There is zero question that you need a non cycling gun (bolt, single shot, no gas semi, etc.) to be really quiet. Its amazing the amount of noise in a semi action. I have a bren2 that has a gas option of no gas and when shut off the sound drops by half in perceived sound.

quote:

I'm assuming you mean standard "off the shelf" cartridges and not ones made specifically for the task of being quiet.

Not sure what you mean on this. You can commercially get .300bo subsonic and lots of other cartridges in various flavors are naturally subsonic. In my 9mm example the difference between hush (produced as you say to be quiet) and 147g (naturally subsonic) is like 2dba. So not a big amount. In any case the OP didn't say any restriction and of course the whole premise is just a fun discussion. Me personally if I want to make 100y shots that have to be lethal as a matter of personal safety and have to be quiet I'm using .300bo because it has lots of energy and is pretty darn quiet. But other than energy its not really different than a 9mm in terms of ballistic at 100y. So I wouldn't panic if all I had was a suppressed 9mm MP5 etc.
Of course YMMV on all this. When I have some time I'll see if we can find some bolt pistol caliber sound ratings.

I think we can all agree on a bolt action platform.

I know there are some crazy quite tiny rounds out there which is why I added the 100 lethality requirement. This was added to create some functionality other than putting a hole in paper.

I got curious about the subsonic 308 since I have a 308 bolt gun. There are commercial loads available but things get a little challenging when trying to made a custom load. Several other forums mention the need for a specific Trail Boss powder and magnum primers.

300 blkout does check a lot of boxes. Being available to purchase over the counter goes a long way too

Well, let's widen the scope just a hair from the other agreed on action types one more to lever action. There's a number of lever guns coming out now that have threaded barrels from the factory.

There's also this interesting new critter that's come out. 8.6BO wiith 165-220gr bullet weights should deliver better energy at 100 yards than .300BO, but again, I don't know that either of these is going to be as quiet as something like a pistol round in any given caliber.

On a side note, Jon, that gives me the only reason I've thought of not to have HBI do the gas plus on my Bren, and it's not a bad one, at that.

Man, I've been wanting to do a bolt gun next, being about sick of AR's now, and this thread isn't helping, lol.

I wish HBI would offer a cutoff as one of the choices on their Bren2 gas plugs. But I'm sure demand for it is probably low.

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being about sick of AR's now

Hold your tongue!

quote:

I wish HBI would offer a cutoff as one of the choices on their Bren2 gas plugs

That looks very similar in function to a 55X valve. It would just require a half-competent machinist to get you a fourth detent notch on there, to orient an undrilled portion of the valve over the port.

What I really want is for CZ to sell me an undrilled gas plug and then I can make what I want. But alas you can't get any parts out of CZ for the Bren at the moment which is the real underlying issue. HBI is just filling that gap with a product that works for most anybody.
Off topic for this post.
I looked really hard to try and find a 9mm bolt gun and some decent sound data, but it doesn't seem to exist. But I did find a 9mm bolt gun that I now want!.
P220Smudge is a way better internet warrior than I am maybe he can find some 77/357 actual data because the videos I saw of that were pretty darn quiet firing .38 special subsonic. But nobody had any actual meter data...
I was able to satisfy myself that 9mm subsonic is actually quieter then .45ACP subsonic under any circumstances FWIW>

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