First reloads for 300 black out

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Theskytoucher
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First reloads for 300 black out

Post by Theskytoucher »

Back story: I put together a 300 blackout AR pistol at the beginning of March. Aero precision lower and a complete upper from B.king ballistic advantage 8” with 1/7 twist. Right after I finished the build everyone started panic buying ammo and I was only able to get one box of 50. Which I proceeded to take and shoot to function test the gun. Flawless.
I have been reloading for a few years for 9mm, 40 cal, 45 acp and .223. Probably loaded 5000-6000 rounds at the point. (I know rookie numbers, but I’m doing what I can)
I went and bought a pound of CFE blk lee pacesetter dies a lee universal expanding die cci 41 primers gallant 220gr hitek coated lead projectiles and 500 pieces of new brass from Everglades.
Going off load data by Hodgdons and other info found around the internet I started with 11.5 gr and a oal of 2.100 then did 12 gr and 12.5 gr. I loaded 10 of each and got to the range and was running out of light so I put them all through a piece of plywood.
My question to all of you experienced 300 blackout loafers and shooters in the picture below does it appear that I am having stability issues with at least a few of the shots https://photos.app.goo.gl/4pVsyvKMhfvmafY87

Thank you in advance
Aero precision lower, B. King complete upper 8” ballistic advantage 1/7 barrel.
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certifiable
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Re: First reloads for 300 black out

Post by certifiable »

The target boards at my local club are plywood and it has been my experience that when slow heavies hit a target stapled to plywood the bullets most often start to tumble as they pass through leaving slightly oblong shaped holes.
"America will never be destroyed from the outside.
If we falter and lose our freedoms, it will be because we destroyed ourselves."

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Theskytoucher
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Re: First reloads for 300 black out

Post by Theskytoucher »

So don’t be to worried at this point. And do more testing. If I am reading your reply correctly?
Aero precision lower, B. King complete upper 8” ballistic advantage 1/7 barrel.
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certifiable
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Re: First reloads for 300 black out

Post by certifiable »

Too get a better idea of stability try attaching your target a cardboard box. The need for further testing depends on your end goal for your load. You didn’t post any chronograph numbers so I have no idea if you are within the subsonic realm as I have not done any testing with that Hodgdon powder.
Btw, when working up sub loads you should start high and work your way down in powder charge to help avoid a stuck bullet.
"America will never be destroyed from the outside.
If we falter and lose our freedoms, it will be because we destroyed ourselves."

Abraham Lincoln
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dellet
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Re: First reloads for 300 black out

Post by dellet »

CFE BLK is a powder that you have to use a chronograph working up a load or you can easily have a disaster. It does not perform well with low density loads. I would not be surprised if some of those rounds were less than 800 fps. in an 8” barrel. That slow can easily cause stability problems.

If using data for a 16” barrel, I would add 1.5-2 grains as a starting load in an 8”. With that powder pressure is not a problem, Velocity, or lack of, is. It’s really kind of a poor choice for a short barrel, but it’s usable, just keep the bullet close to the powder or compressed is even better.
300 Blackout, not just for sub-sonics.
Theskytoucher
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Re: First reloads for 300 black out

Post by Theskytoucher »

Dellet,
I did a bunch of reading last night on your working with cfe blk. This afternoon I checked case capacity and it appears I need 13.5 gr of cfe blk at a coal of 2.100 to get a very slight compression on the powder. (Pushing bullet in by hand upside down to ensure a full case) I can with almost no effort push the bullet to 2.115. At this point I am not running a suppressor nor do I have plans for one in the near future. I am simply looking for a plinking load to go out and shoot cans and steel targets with. Also teaching my 12 year old son how to shoot a larger rifle than 22lr. With the above reference of adding 1.5-2 gr over published data I think this will be a decent plinking load. I also checked the bulletin jump in my rifle which is around .040 averaged over three try’s with a fired case.
Aero precision lower, B. King complete upper 8” ballistic advantage 1/7 barrel.
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dellet
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Re: First reloads for 300 black out

Post by dellet »

If I were you, I would load for accuracy. Without a suppressor, the difference in sound will be almost impossible to distinguish unless you shoot past 100 yards. At 50, it is almost impossible for me to tell subsonic by ear, sometimes even suppressed.

Basically by the time the muzzle blast dissipates, the bullet will have likely dropped below the point it cracks or will have hit the target.

I can almost guarantee that your son will not even notice the noise, if he’s hitting the target. If he can’t hit then the noise may become an excuse. It is loud in a short barrel.

Something else to consider is a Simple Threaded Device. Made by member Jim Timber. It works very well at projecting sound and concussion forward from the shooter and at the same time reducing flash. It’s a very good muzzle device. He did a lot of the development work using this cartridge and short barrels.

viewtopic.php?t=83301&__cf_chl_jschl_tk ... YhyWfFmrHQ

https://simplethreadeddevices.square.site/
300 Blackout, not just for sub-sonics.
popper
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Re: First reloads for 300 black out

Post by popper »

Might try MBC #1 whitetail hitek and ~8gr A2400 in that pistol. Not sub, more like 357 but very little recoil. Bang - whack! Played 100 rnd 50 yd 'whack-a-mole' last time, fun and did pretty well. Multiple 1" targets spread out so you 'bounce' between targets ~ 1 sec between shots. No double taps allowed, range rule
Theskytoucher
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Re: First reloads for 300 black out

Post by Theskytoucher »

Again I am not worried at all about sound level. So yes I will be loading for “accuracy” by that I mean being able to hit 8 in gongs at 50 yards with a red dot. My son is already a pretty good shot with both a 22lr and a 9mm pistol. Part of the reason behind building the pistol was making it compact and light enough for him to handle. My 16” at-15 in .223 has to much forward weight for him to be able to shoulder standing and be accurate with. My original issue of stability was asked because the holes looked weird to me and and an unstable bullet could cause weird results shooting steel. I went out and tested some with 13.5 gr and seated to 2.095 and at 25 yards they all cut clean holes so I think I found a starting point to try and get some accuracy. At “rapid” fire I put 20 rounds into a 5 3/4” group.
Aero precision lower, B. King complete upper 8” ballistic advantage 1/7 barrel.
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