Bullet Weight for 300 BLK Sub AND Super ?

[BulletFactory]

I would like to use one bullet weight for both subs and supers in the 300 Blackout. What weight/design would you guys recommend?


It would be better than buying 2 molds and 2 handles, just all around more convenient.

[Smoke4320]

What is your twist rate and if an AR the gas system length

[BulletFactory]

AR pistol gas 1:7 twist

1,000 posts ! woohoo:cbpour::guntootsmiley:

[BK7saum]

I load the MP 311410 hollowpoint subsonic. And have killed a few pigs with it. It would be a good supersonic boolit also. For reliable penetration with an exit you might consider a 160-180 grain mold. I don't have a recommendation in that department though.

[Moonie]

If it's an AR you generally are limited to boolits heavier than 200gr for reliable cycling, you can shoot them both sub and super, I load 235 and 245gr boolits at super and subsonic velocities. If it isn't an AR it really doesn't matter, I also have a 7.5" Encore pistol that I load light weight boolits with fast powders at subsonic velocities as they are nice and quiet through my suppressor, but those loads will not cycle an AR.

[Artful]

OK, you want everything out of one boolit - I've taken to using the Ed Harris 155 gr design for super sonic - it works well - if I wanted to use this as a subsonic, I'd have to alter my firearm to get it to work.

Pistol port and carbine port on the same barrel - with adjustable gas blocks at both places.
http://www.ar15.com/media/mediaFiles/161452/15553.JPG

[BulletFactory]

I have never seen that done before, cool !

[BulletFactory]

I have a 168 grain gas checked mold for the .308. Would that be a good choice? It would be nice, since I could cast once, for three rounds.

It is an AR pistol 9"

[runfiverun]

I think you can pull it off with the 168.
9-10 grs of 4227 for one end and 15ish for the other.

[yondering]

I would like to use one bullet weight for both subs and supers in the 300 Blackout.

I think you may not understand how an AR gas system works, and what the effect is of increased pressure on the gas system. You're venturing into dangerous territory here that can tear up your gun or worse.

There is a really good reason the 300 Blk AR system is designed for light weight supers and heavy subsonics - to balance gas pressure/volume to the bcg with both types of loads.

Think about this for a minute - if you have a medium-heavy bullet, say 168-180gr, and figure out a subsonic load that cycles the action. Now, what do you think happens in the action when you turn up the pressure with that same bullet? You'll have a severely overgassed system that's going to beat up the action, and likely even unlock the bolt too early before pressure drops; this is very bad.

Or, you might figure out a supersonic load that cycles correctly (you will need to restrict the gas to do this with 168-180gr bullets); a subsonic load with the same bullet won't cycle the action, unless you use a much slower powder and somehow get it to ignite correctly.

[BulletFactory]

You are right, I do not completely understand the AR, this is my first one.

I will need to get a mold soon, would you recommend a 150 grain or a 130 grain for supersonic only?

NOE has a nice spire point at 150, and RCBS has one for 130 grains. NOE also has a 220gr that I could use for subs.

[BulletFactory]

http://noebulletmolds.com/NV/product_info.php?cPath=30_359&products_id=209

http://noebulletmolds.com/NV/product_info.php?cPath=30_360&products_id=3198

https://www.midwayusa.com/product/305808/rcbs-2-cavity-bullet-mold-762mm-130-spl-762-mm-30-caliber-309-diameter-130-grain-spitzer-point-gas-check

[Artful]

Or, you might figure out a supersonic load that cycles correctly (you will need to restrict the gas to do this with 168-180gr bullets); a subsonic load with the same bullet won't cycle the action, unless you use a much slower powder and somehow get it to ignite correctly.

Or tap the gas at a different position on the barrel - duh

https://300blk.files.wordpress.com/2013/04/wpid-photo-apr-12-2013-914-pm.jpg

Remembering that the AR platform with original 20 inch barrel in 5.56
http://www.ar15barrels.com/tech/223plot.gif

I'm using this
http://leeprecision.com/images/P/90385-01.jpg
http://leeprecision.com/mold-6-cav-c312-155-2r.html

but your 168 will probably work just fine once you find the correct OAL

[bruce drake]

Artful,
Could you send me a PM with the specs or a writeup on that double port system? I've got a few things going on my in ahead about extending my current gas system on my 30 Apache AR from Carbine to rifle length and I think you may have the solution in that double port system with the shut-off valves. My 30 Apache runs perfectly currently with the Carbine gas with Super-sonic loads upto 147gr but the longer gas system may smooth out the operation a bit more.

Thanks,

Bruce

[yondering]

Or tap the gas at a different position on the barrel - duh

Sure, but that dual gas port setup you showed is not a normal AR15 setup, or what the OP has. Really not a "duh" solution. Just going with a longer gas system works for only supers, but is counterproductive for subsonic loads.

You can't tune a normal AR15 gas system correctly for both 125gr and 168gr full pressure supers, if you're using ideal powders for both.

[yondering]

You are right, I do not completely understand the AR, this is my first one.

I will need to get a mold soon, would you recommend a 150 grain or a 130 grain for supersonic only?

NOE has a nice spire point at 150, and RCBS has one for 130 grains. NOE also has a 220gr that I could use for subs.

I haven't used the 130gr RCBS, but use the NOE and Lee 150/155gr bullets (they are very similar) for supers in my 9" 300 AR pistol. They aren't ideal, as the system works better with lighter bullets, but are the best option available right now for cast bullets (except maybe the 130 RCBS, don't know but it looks like it should work really well). Supers in this caliber really are best with 110-125gr jacketed bullets right now, but I shoot a lot of the 155gr cast stuff at slightly reduced pressure for most of my practice. When tuned to run those, my AR will not cycle cast bullet subsonic loads below 200gr, without using really slow powders. It runs anything from 200-270gr cast subsonics without issues though.

I do also have a 168gr cast bullet that I have used in mine for supers, but if it's run at full power, the issues I described above show up in the system. Same for anything heavier than that at full pressure, unless you move to very fast powders, which defeats the purpose. (Gas port pressure is partly a function of burn rate, in general slower powders result in higher port pressure, all else being equal.)

[Artful]

You can't tune a normal AR15 gas system correctly for both 125gr and 168gr full pressure supers, if you're using ideal powders for both.

You can with the right modifications.
https://media.midwayusa.com/productimages/880x660/Primary/578/578769.jpg
The Noveske SwitchBlock is an adjustable gas block designed to improve function and reliability when using a suppressor. The Switchblock is constructed of 17-4ph stainless steel for its corrosion and heat resistance with a black nitride finish. The block has three gas settings; Unsuppressed, Suppressed, and OFF. The settings are easily changed by depressing the locking plunger and rotating the knob to the desired setting. The suppressed setting reduces the amount of gas entering the system, counteracting the increase in gas pressure and volume when firing with a suppressor attached. The suppressor setting brings the gas pressure and volume closer to the normal levels, reducing the fouling, cyclic rate, and recoil normally experience with standard gas systems and suppressors. The OFF setting of the Switchblock will operate the rifle in a single-shot mode, eliminating the sound of the action cycling and controlling the brass ejection.
https://www.midwayusa.com/product/578769/noveske-switchblock-gas-block-clamp-on-ar-15-standard-barrel-750-inside-diameter-stainless-steel-black-nitride-for-223-556x45mm-carbine-length-gas-145-to-16-barrels

[sfcairborne]

181659181660181660Here's an ACE MOLD THAT CAST 145.5 gems without gas check. As cast .311. Send me you address and I will mail it to you. That takes care of your super

[BulletFactory]

PM sent.

In case PM is still down, heres my info

[sfcairborne]

Got pm, will mailout this Friday or Saturday depending on workload. Enjoy

[BulletFactory]

cool, thank you I got into PMs too. Mods, they seem to be working. Thanks computers can be such a pain.

[yondering]

Sweet deal on that Ace mold. That should work really well for supers.

Was that a group buy mold here?

[sfcairborne]

No, I bought the mold from a group buy on the 300 blackout forum. It's not a bad mold. Kinda have two of them.

[runfiverun]

you'll like that mold.
I buffed my nose out a tick for the wife's 300 but it came as specced.

[yondering]

No, I bought the mold from a group buy on the 300 blackout forum. It's not a bad mold. Kinda have two of them.

I'm on there too but must have missed that one. Will have to check it out, thanks for the info.

[popper]

Question - why heavy subs in BO? Not knocking them, I've shot Rem 220gr stuff that works - wasn't impressed. No intention of getting a can - as long as they are NFA items. Is there a real reason? Or just because? Dolomite is trying for a 300gr & some other stuff I don't think will work. I can use light to heavy supers for target and hunting. $ wise it's a tradeoff between powder and lead cost. I know the reason for the whisper 'invention' but I'm not on a Seal team..

[BulletFactory]

I think that it's because in order to operate the gas system in an AR, you need the extra mass (newtons 3rd law) when using subs. On the same note, you need lighter supers, with their higher velocities to cycle the action.

[odfairfaxsub]

I you want a bullet weight that will proper sub and super then the weight is 200. I can run both these and function w a carbine gas port.

[yondering]

I you want a bullet weight that will proper sub and super then the weight is 200. I can run both these and function w a carbine gas port.

If your 200gr supers are at full pressure, then that system is way over-gassed, unless you're changing something in the gas system to switch between subs and supers.

[yondering]

Question - why heavy subs in BO? Not knocking them, I've shot Rem 220gr stuff that works - wasn't impressed. No intention of getting a can - as long as they are NFA items. Is there a real reason? Or just because? Dolomite is trying for a 300gr & some other stuff I don't think will work. I can use light to heavy supers for target and hunting. $ wise it's a tradeoff between powder and lead cost. I know the reason for the whisper 'invention' but I'm not on a Seal team..

Because light weight subs don't cycle the action?

If you're asking why subsonics at all, you won't understand if you aren't interested in a suppressor.

[sfcairborne]

Yep to the above statement. I've got a can and I don't think I've taken it off my blk run suppers and heavies thru it. Gotta have one to understand

[BulletFactory]

Once you shoot one, you will want one.