300 Blackout AR Pistol reloading

[Batman79]

Hello everyone,

I'm new to the forum and new to 300 AAC Blackout. I've been reloading since 2011 with various calibers (Rifle and pistol). I recently purchased a Daniel Defense DDM4 PDW which is a 7 inch AR pistol in 300 blackout. I'm struggling to find good data on supersonic AND subsonic powders and loads tailored to a 7 inch barrel. My aim is to extract the maximum amount of burn for supersonic and subsonic with this setup. I've heard pistol powder is defiantly the way to go with subsonic in this configuration but I don't have the chronograph ability to test at-will with grain increments. So, has anyone done any testing with this scenario, I'm not looking for exact science but test barrels should be 6-8 inch range to get me in the ball park. My current list of powders are below:

AA #9
CFE Pistol
Hodgdon Longshot
H335
H4198
Winchester 296
Alliant Unique

Kind regards.

[B767capt]

Good post as I'm in the same boat with the same gun. I'm adding a DDWave suppressor on it too. Curious to see what the recommendations are.

[Batman79]

Sweet bro, what's the expected wait time to get your wave? I'm leaning towards that one as well. As for the reloading I've be doing some research with reloading software as well as other forums and Youtube. What I've come to the conclusion is the best powders for our platform are going to be lil gun and W296 for subs. Surprisingly W296is great for supersonic as wellJohnny's reloading bench on YouTube has done a lot of videos with it although he is a 16 and 8 inch barrel. I was just able to order 5000 small rifle magnum primers from Midway last night and I have some casings coming in that I'm going to trim down. My 225 gr projectiles from GT bullets, it's a hollowpoint lead cast are on backorder but they should be In within a few weeks . I will update more once I get some loaded up and testfired, don't have a chronograph or land to really test on so will it will be difficult convincing a range to let me use a chronograph in the Houston area, If can get a hold of one.

[B767capt]

I used Silencer Shop and they said 3-6 months until they can get some. So I bought one and will wait. I like the looks and attachment setup on the QD.
I have lots of Lil Gun from pistol reloading and just ordered all the 300BO conversion parts from Dillon today for my 650. 300 BO dies are back-ordered there too. Thanks for the info and just read about the Starline brass issue here as I ordered 1k and that's back-ordered. Good find on the primers as I've been looking for days and that seems to be the hardest part to get. I have a chronograph and can't wait to check it out. I plan on just subsonic.

[phils3]

For supers use the W296 or the AA#9, leaning more towards the 296. Use 125-150 gr bullets. I personally like Ramshot Enforcer for supers out of my 8” barrel. Start low, get to mid range charge and then SLOWLY work your seating depth down. This will get you a little more velocity and limit your muzzle blast. With a 125 gr flat base bullet seated so that the base of the bullet is right where the neck meets the shoulder and 18.0 gr of enforcer I’m getting around 2000 fps out of my 8” barrel.
For subs out of a 7” barrel you will need powders in the A1680 to CFE BLK range. You can try using the H4198, but you might need something a little slower. You probably won’t be able to get any subs to cycle unsupressed. Either that or you will need to open up (drill out) your gas port on your barrel. Since you have DD I would not suggest that. CFE BLK makes almost everything cycle (supressed) but it’s kinda loud and verrry dirty. If you use cast/coated bullets drop your charge .5 to 1.0 from the listed with jacketed bullets, also, make sure your crimps are very consistent, as varied crimps will play with your velocities. Use at least 220 gr bullets, start at a listed manufacturer charge weight and just keep dropping your charge weight until you get the lowest that still gets you BHO on the last round.
Any small rifle primer will work until you start to get into the mid range charge weights for supers, use Rem 7.5 primers after that.

[plant.one]

to do subsonic load development - safely - a chronograph is almost mandatory.

the kick is - unlike supers where you start low and work up watching for pressure, with subs you start high and work down. Problem being - too low and you stick a bullet in your barrel which can make bad things happen - especially if you were to pull the trigger without clearing it first, which can be enough of a pain, and will end your range session at the very least.

so without a chrono to know you're subsonic and still in a safe velocity range (lets say >950 fps just to put a number on it, its probably lower, but you get my point here) so that you dont have a problem... well yea.. you're just in WAG (which since this is a family friendly site = wild @$$ guess) territory.


because of the safety concerns - i strongly recommend you beg, buy or borrow a chrono before you head down the subsonic load testing road.


the scars you dont earn and the eyes you save may well be your own.


safety first!

hth

[jtcarm]

I'm in the same boat, though I have more than a few years reloading experience on you. I just built a PDW that will double as a hog gun.

From what I've found scouring the web and asking around, s-l-o-w pistol powders are the way to go for super, powders like Lil gun, H110 (essentially the same thing as 296), IMR-4227, Aliant 2400. Basically the same stuff you'd use in magnum pistol rounds or small rifle rounds like .22 Hornet.

I have no experience with Accurate, Vita-whatever, and other newer powders. Being an old goat, Hodgdon, IMR, Aliant (FKA Hercules) and Winchester powders have always handled my needs. I prefer shooting to experimenting, unless I hear something really good comes along (like Lil Gun).

I'll be starting out with some Speer 150-grain Hot-cores as well as the Sierra Pro-hunter 125 JHP designed for .30/30 (pricey but looks like it should be deadly in 300.)

That is, when the Romeo5 and reloading equipment get here.

[T-RoyJenkins]

I am also new to 300blkout reloading. I acquired 8lbs of A1680 and a pound of CFEblk along with a few 200gr. ELD-X projectiles. I cannot find any specific data on these powders with this projectile. I am looking for a subsonic load out of an 8" barrel. Any help would be greatly appreciated!