300 blackout subsonic question- scientists jump in

it can if the bullet is designed for the intended velocity. 308 bullets are designed to stay together at high velocity's, and then expand when hitting something, bullets like the .45 are designed for slow velocity. If you fired a 45 ACP hollow point at 2000+ fps it might not even stay together.

There are a few .308 bullets that are a little less 'gee whiz', like the Barnes Tac TX, the Hornady VMax, Speer TNT etc that can expand in the 300 BLK if Lehigh or Makers etc aren't your cup of tea. Of course, they aren't subs. I've seen guys shoot the Hornady 95 grain XTP subsonic with some success, but a 180+ grain bullet that is designed for 2500+ fps is almost never going to expand subsonic.

It could with a properly designed bullet, but that's a tall order with a long, skinny, pointy pill at such low velocities.

I have a .300 BLK, but I seldom use it. I'd rather run large bore handgun rounds for subsonic stuff to be suppressed. I'm still working on it to sort out feeding issues, but I built a 10mm Magnum AR upper with the intention of swaging 300 gr (or heavier) JHPs to run at subsonic velocities.

.45 bullets are designed to expand at 800-900fps. Most +200gr .308" bullets are not. Plus, due to a significantly lower sectional density, it's easier to get a 230gr .45 to expand at 800fps than a .308" bullet. Thus, companies like Lehigh have to get really creative in coming up with a .308" design that will expand at subsonic velocities. I've got some of the Nosler 220's to test but haven't yet.

This is a primary reason I question the utility of sub-sonic rifle rounds in general and regard the .300 BO as a fad cartridge you probably don't really need. I would rather have a .458 SOCOM, but even then you're better off with specialty projectiles if you go sub-sonic, and the SOCOM obviously requires more modification from the AR to function properly.

As noted, most rifle bullets are designed to perform at rifle velocities. In order to get rifle bullets to expand below 1600-1800 fps, you need specialty projectiles with thinner jackets and larger hollow points, hence the Lehigh and others. But these are very specialized projectiles that fill a very small niche--hence the reason the are expensive and not very popular outside that market.

I have seen evidence that you can cast your own projectiles and powder coat them. A soft lead projectile can deform at subsonic velocities and the powder coating is supposed to keep too much fouling from gunking up your suppressor.

https://www.youtube.com/results?search_query=.300+blackoutpowder+coating

But that of course requires you to acquire some lead, molds, manuals, ect. In the long run it might be cheaper than a steady diet of Lehighs, but in the short term, definately not. And it certainly requires more work from you.

I'm relatively new to the 300 Blackout cartridge and loading for it. Wisdom if found by following threads like this and casting your own subsonic .308 bullets does seem to be the next thing I should try

MTMilitiaman said:

This is a primary reason I question the utility of sub-sonic rifle rounds in general and regard the .300 BO as a fad cartridge you probably don't really need. I would rather have a .458 SOCOM, but even then you're better off with specialty projectiles if you go sub-sonic, and the SOCOM obviously requires more modification from the AR to function properly.

As noted, most rifle bullets are designed to perform at rifle velocities. In order to get rifle bullets to expand below 1600-1800 fps, you need specialty projectiles with thinner jackets and larger hollow points, hence the Lehigh and others. But these are very specialized projectiles that fill a very small niche--hence the reason the are expensive and not very popular outside that market.

I have seen evidence that you can cast your own projectiles and powder coat them. A soft lead projectile can deform at subsonic velocities and the powder coating is supposed to keep too much fouling from gunking up your suppressor.

https://www.youtube.com/results?search_query=.300+blackoutpowder+coating

But that of course requires you to acquire some lead, molds, manuals, ect. In the long run it might be cheaper than a steady diet of Lehighs, but in the short term, definately not. And it certainly requires more work from you.

Click to expand...

I personally drilled the 220gr. round nose projectiles but in order to have enough size to the hollow point to insure expansion the bullets were more in the 180gr. range after I drilled them. I did develop a good consistent sub sonic load for my use using 220gr. comercially available bullets.
Thanks for your post OP

I usually dont do this, but, why do you need them to expand ?

And do you need them to expand so often that buying 20 of the specialty bullets wouldn't work for you ?

Shooting deer ?
Thats 20 deer.

Hot off the press:

https://www.hornady.com/ammunition/subsonic#!/

"Performance of the Hornady® Subsonic 300 Blackout load meets or exceeds FBI Protocol terminal ballistic test requirements."

As designed they are expected to hold up to 2500 FPS. Cant have that AND subsonic performance there. can help make those 308 win style bullets work a little better at slower than designed speeds if you want to anneal the tips a bit, and maybe do some drilling. Search around a bit and you can find some decent results. Nothing as good as the purpose built bullets, but they can be quite decent!

All that said, the lehigh ME bullet is worth every penny. The black tips are worth every penny if you are going supersonic.

I've heard a fair amount of chatter of poor performance on game of .300 BLK subsonic. So if I may engage in a small tangent of subsonic chamberings generally (if not, please delete) .... This issue is why I ditched the .300 BLK / .338 Spectre idea, and instead shoot these bullets:

https://www.badmanbullets.com/OnlineStore/proddetail.php?prod=38/357-230-WC-Bowling-Pin-Qty-500

...subsonic (reduced loads) from a single shot T/C Encore in .357 maximum. Full .357" meplat and soft lead - they will and do expand massively and do a lot of damage. They do stabilize from a 14 twist barrel too (not sure about 16 twist). Brass lasts nearly forever. Couldn't think of any possible use for a semi-auto subsonic rifle, so this is what I decided to play with for subsonic / suppressed (along with .22lr in turnbolt format with Aguila SSS's). Have yet to hunt with the .357 but I plan to (unsupressed in this state). Just food for thought.

However, I just recently decided to also try some subsonic loads in 5.56x45 out of an AR15 platform with 75 grainers, but don't expect them to cycle. Haven't made a load yet. The reason I decided to try this is for something a bit lighter than the .357 max, for varmints around the homestead near neighbors, since I can't get the Aguila SSS 60s to shoot accurately enough for my tastes (even WITH a 9 twist!) --and since the CCI "Quiet" is too loud and the Super Colibris are likewise lacking in accuracy. Plus the Aguila SSS is *too* subsonic out of a rifle barrel - it may only get to 800 or 900 fps. Heck if you're gonna be limited to subsonic, at least max them out up to the limit of the speed of sound (which is 1050 at 0 deg F up to 1160 at 100 deg F). Oh the 75 grainers won't expand of course, but their use is varmints smaller than yotes, so they are powerful enough for that, I think, even blowing right through. I'm thinking magpies & squirrels on the cherry trees mainly.

My view on the .300 BLK is that if your rifle is wholly dedicated to subsonic / suppressed, with all that that entails, to make it cycle well, the tighter twist rate, etc., and forget completely about using supersonic loads in it, then that is a potentially useful niche tool (for just fun, or a theoretical WROL scenario). But a supersonic? Nah, 6.8, 6.5G, 5.56 and several others are superior if willing to go supersonic. Dual purpose, switching back and forth? Nah - that's an even bigger fail - way too much hassle.

That Hornady .300 BLK 190 bullet / loaded ammo looks like it's what was sorely needed however - if you go that route.

Hornady V-Max bullets are varmint bullets and are totally unsuitable for anything but varmints. A-Maxes are not hunting bullets either. They're match bullets, but are suitable for varmints only. No deer sized game with either of 'em. Suppressed or not.
Varmint bullets are designed to expand rapidly upon impact with little penetration. Target/match bullets are not designed to expand at all. So if you're using either on deer, that explains any kind of "poor performance". It's the bullet's construction, not its velocity.
"...drilled the 220gr. round nose projectiles..." That doesn't work any more than cutting the points off milsurp FMJ's. It's the jacket that makes 'em expand or not expand reliably. And you very likely have bullets that are wobbling due to the inconsistent balance.

seems like if you want expansion and subsonic, cast lead would be a obvious answer. The BO is a round designed for reloaders https://www.midwayusa.com/product/1...n-300-aac-blackout-tumble-lube-5-ogive-radius I bet these expand fairly well with pure lead

seems like if you want expansion and subsonic, cast lead would be a obvious answer.

I've never tried soft lead 300BLK bullets, but I've used Missouri Bullets 240gr lead bullet designed for subsonic 300BO. Those are BHN 20. IIRC, he said they were harder than other subsonics because the soft ones had problems deforming during the trip from mag to chamber in the AR.

I happen to like my gee whiz bullets from Lehigh...they are a local company and are awesome to talk to in person. I find this thread to be silly as the OP clearly seems to have something against Lehigh and other companies that actually make an expanding bullet at subsonic speeds.

I hunt with my 300BO, so it's going to be 194gr ME or 174gr CF from Lehigh or the Outlaw State bullets. For me 300BO is pointless if it's not shot subsonic/suppressed and I hunt so expanding bullets only for this guy. I lost a deer using Hornady 208gr Amax.

ditto on that. 115 grain Controlled Chaos dropped a Minnesota white tail yesterday.

aubie515 said:

I happen to like my gee whiz bullets from Lehigh...they are a local company and are awesome to talk to in person. I find this thread to be silly as the OP clearly seems to have something against Lehigh and other companies that actually make an expanding bullet at subsonic speeds.

I hunt with my 300BO, so it's going to be 194gr ME or 174gr CF from Lehigh or the Outlaw State bullets. For me 300BO is pointless if it's not shot subsonic/suppressed and I hunt so expanding bullets only for this guy. I lost a deer using Hornady 208gr Amax.

Click to expand...

Cast lead!
I loaded a mag full of blackouts with some 194gr cast bullets I used to play with in my .308. It was awesome. Quite, cycled reliably, they would kill for sure based on my .308 experience with them. Just clip on wheel weight with Lyman moly lube and gas checks(not needed for sub sonic blk)

Id use a heavier bullet if I was buying a new mold. It would be smart to powder coat if your suppresser isn't serviceable.

Cast lead with a wide meplat kills good, really good in calibers .308 and up. In something like a 45 acp you won't find a better quality hunting bullet in any price range.
My belief is when something is under powered (like a subsonic blk or a 45 acp) for hunting say a deer or pig. The lead lubricates its way through the flesh. The meplat cuts a nice channel too if the shape is right. I've shot many pigs with a cast bullet moving 1800 from a .308 it just works (somehow) the only negative I've found is it's about impossible to lead a running pig or coyote with a slower bullet.

Decoy80 said:

I personally drilled the 220gr. round nose projectiles but in order to have enough size to the hollow point to insure expansion the bullets were more in the 180gr. range after I drilled them. I did develop a good consistent sub sonic load for my use using 220gr. comercially available bullets.
Thanks for your post OP

Click to expand...

I've found a #3 center drill is perfect for the task. The drilling job is easier if one first cuts the front to make a flat surface or uses a FMJ bullet (or Nosler Partition) and drills the hole in the exposed lead in the base and then loads and shoots the bullet backward.

Expansion is very reliable, and these are easier for small quantities than casting lead.