Beginner 300 blackout

[Machineguntony]

I'm starting to reload for 300 blackout.

Yes, I've fallen for the fad. But I'm falling in headfirst.

Why does 300 blk use different powders than 223? Is it because of the bullet size generating different pressures? I was under the impression that 300 blk and 223 use the same powders. Looks like I'll be buying more powder, as none of my 223 powders seem compatible. Anyone reload 300 blk with 223 powders?

What velocity do I need to look for to determine if a round is subsonic? Is it possible to create a subsonic round with a 150 grain bullet?

I need it to cycle my 8 inch AR.

[Old Bill Dibble]

Here is a good list of powders to use:

http://www.300blktalk.com/forum/viewtopic.php?t=86656

It is a couple of years old but still valid. You have subsonic and supersonic powders.

The speed of sound is 1126fps at sea level. anything below that is theoretically subsonic. This decreases slightly with increased elevation. Temperature increase will cause the speed to increase, decrease will cause it to decrease. For all practical purposes 1025fps will be subsonic in any environment that humans can survive in.

You can create a subsonic round with a 150 gr bullet but it defeats the purpose. The heavier mass of the 190+ bullets do the work at the lower velocities. You give up a lot of energy on a slow moving bullet by reducing the weight.

[berettaprofessor]

I chose IMR4227 for my 300BO...because I could find data for both supersonic 150 and subsonic 208 loads.

[Chainsaw.]

4227 again. Most folks shoot for 1050fps as its far enough from the sound barrier that if you get some bad powder metering you still have a margin of error so as not to go over. If you're trickling powder you could certainly push closer but then the question is what will another 25-50 fps gain you.

[Sharkbite]

Hey Tony,

Welcome to the Blackout crowd.

First let me reccomend a forum specific to that gtg. 300blktalk.com. You'll find me there under the same screenname. There is a whole section on load data.

For general info...

If loading supersonic for max velocity, H110/W296 is a good choice.
Supersonic plinkers...4227 does a good job
Subsonic (thru an AR) 1680 rules the roost.
Subsonic thru a bolt gun (where it gets REALLY quiet) lots more options in powder choices.

As you note most Blackout powders are in the magnum pistol range, not "Rifle" types. That is one of the reasons it is so efficient in shorter barrels.

[Machineguntony]

Thanks fellas.

I'll visit the website, Sharkbite.

I'm at the Eggleston Munitions website, and they have 500 pack of 300 blk bullets for $67.39 (they do have 15% off this Labor Day and $5 shipping). Does anyone know of a cheaper source for 300 blk projectiles? I'm looking for cheapest per bullet.

Also, the website recommends .309 sizing for 300 blk. What size do you guys use? I've never thought of sizing my bore. I just buy bullets. Is there really a practical difference between a .308 and .309 bullet size?

[orionengnr]

Why does 300 blk use different powders than 223?

Well, for starters, a 55gr projectile moving at 3200 fps vs a 150 gr projectile moving at 2200 fps?

Is it possible to create a subsonic round with a 150 grain bullet?

Sure. It is possible to do lots of things.

For instance, it is possible to create a subsonic 5.56 round.
But. What is the result? A 55 gr pellet travelling 1050 fps. Consider for a moment...how different is that from a .22 LR which weighs 40 gr and travels 1100-1200 fps? So, do you want to spend your time and 4x-5x the money loading a round that is essentially a .22LR?

So...with your subsonic 150...what is the result? It is essentially a .38 Spl round fired from a rifle, without the larger diameter bullet. But with all the cost and effort. And what is the benefit?

Also, the website recommends .309 sizing for 300 blk. What size do you guys use?

As a rule of thumb, a lead projectile is slightly larger than the nominal bore size.

[Sharkbite]

Tony,

They recommend 309 because a lot of guys are shooting 7.62x39 bullets in their blkouts. Those bullets are .311. So, guys resize em down to 308/309 to use in the blackout

I have never gone thru that hassle and just buy 308 bullets. Bulk 150gns make great plinkers/training bullets.

I much prefer the 110-125gn range for serious use (supersonic) or the 208gn Amax for subsonic use.

[A pause for the COZ]

I love me some 300 Black out. Not a fad as far as I am concerned.

Its my favorite. Its super easy to load. Almost all loading are in the 90% fill rate or more. For super sonic loads the same powders can be used for jacketed and cast bullets.
Subs I dont have the experience yet. But I will, I have a Ruger American bolt gun in 300 Black out on lay a way right now. Then I will start the process to add a can to it for subs.

That should go along well with my AR15 carbine in 300 Black out and my AR 15 pistol in 300 Black out.
I shoot them by the bucket full.

[Machineguntony]

Will the subs reliably cycle an 8 inch AR?

I'm thinking that I'll go with the Eggleston munitions 200 grain .309 with Accurate 1680. The Accurate website doesn't show a load for exactly a 200 grain projectile, but I'm thinking I'll be able to extrapolate the proper charge.

I just have to be sure 1680 will cycle an AR before I buy 48 pounds of the powder.

Btw, Eggleston munitions has a 15% off Labor Day sale.

[A pause for the COZ]

I dont know about the subs. But the pistol length and 300 Black out is a bit fussy about the gas.
All of mine have been super sonic loads but the same loads I run flawlessly in my carbine are not near as reliable in the pistol.
Short strokes the bolt carrier. Still fiddling with it to get a good load.
But from that result I can for sure say you cant run all the same ammo.
The old adage a gun likes what it likes would be esp true with the pistol length version.

H110, RL-7, A5744, have been good powder for my 300 Black Out.
A5744 is esp good because it seems to generate more gas for the same pressure. its been a real winner for me in multiple cast bullet loads in many different calibers.

[Sharkbite]

Tony,

1680 has been the only powder ive had complete reliability with in subsonic loads.

With 1680 and 208gn Amax's my 9" AAC SBR runs like a sewing machine. I have the load set to deliver right at 1000fps.

Comfortable to shoot with my SDN-6 on it and no ears

[Mobuck]

"Why does 300 blk use different powders than 223? Is it because of the bullet size generating different pressures?"

OK Look at the case capacity of the .223 and .300. The .223 has GIANT powder space compared to the .300(because the bullet takes up so much space inside the case). Therefore, the .330 has to use a "faster" higher energy powder than the .223.
Does this answer your question?

BTW, I use WW296/H110 for supersonic loads and 1680 for subs.

[Machineguntony]

Thanks a lot fellas.

Accurate 1680, it is. When all the parts of my 300 blk are in, I'll update this thread with videos and pics.

From the looks of things, it might be six more months.