Casing shape

[BlkExp98]

I was wondering something when i read about the 300 BLK and wanted some help understanding it if any of you know. I load for .308 and .223 so being able to use the .308 projectile in a .223 case would be an easy transition supply wise.

My question comes from why they didnt use the 7.62x39 case. They plainly state the angle of the large part of the case was the issue. So what is it about that that would make it undesirable in an accurate weapon? Im sure im missing something obvious but i just dont get it unless the straighter wall of the .223 aligns faster in a chamber since its not trying to mate to a taper.

So if i wanted to load the most accurate of the two would you load 7.62x39 with a .308 projectile and have a .308 barrel cut with a 7.62x39 chamber or go for the 300 BLK and make use of all my existing .223 and 5.56 brass.

On another note i have a good many .223 cases that im pretty sure came from winchester whitebox and they have crimps where the bullets were seated. Is this brass ok to reload with or do i need to do something else with it? I could call it the plinking brass and reserve the rest for good loads.

 

[MitchAlsup]

Re: Casing shape

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BlkExp98</div><div class="ubbcode-body">On another note i have a good many .223 cases that im pretty sure came from winchester whitebox and they have crimps where the bullets were seated. Is this brass ok to reload with or do i need to do something else with it? </div></div>

Size-em, load-em, shoot-em.
OR
Brass-prep-em, size-em, load-em, shoot-em {match grade}

 

[former naval person]

Re: Casing shape

I think I'd go for the 7.62 case, simply because of less work and expense. With the .300 BLK, unless someone gives you a batch of cases, you probably will have a considerable amount of case prep. First anneal, expand stepwise from .223 to .24, to .284 then to .308. Probably anneal once in the middle of the process and at the end...all to stop the necks from splitting. 'Then the problem of measuring the necks...most of the time they expand unevenly, so neck turning will be necessary to get good concentricity. Additionally, when you expand that much, the case necks will be thin, so that you'll need to experiment before you buy your rifle and determine the final thickness of the neck and specify the custom chamber neck you need for accuracy...i.e., less slop/neck clearance. Then you'll need custom dies with bushings or honed out for that neck thickness. Then, on to bullet choices and powders for that loading. Your regular .223 powder probably won't work. All in all a project for the experienced. JMHO

 

[jet_lagged]

Re: Casing shape

I don't think the case angle of the Soviet rounds is an accuracy issue.

But when you look at how curved a mag for an AK is, you will figure that with the case geometry involved, using heavily tapered cases, you can only put a few into an AR mag, and have them feed.

Same problem for the 6.5 Grendel.

But with .30/223 or Blackout, you can load a standard AR mag to capacity.

 

[Greg Langelius *]

Re: Casing shape

Bolt face diameter compatibility as well. It just seems that AR platforms tend to be more accurate than ComBloc designs.

My preference is for the .473" bolt face diameter, which makes 6.5-250 (.260 Bobcat?), 6.5-08/.260 Rem (.260 Panther?), .280 Rem (7mm Rem Express), .30-'06, and .30BR interesting chamberings.

For x39 casings, 22PPC and 6PPC, as well as 6.5 Grendel, are options. Might be interesting to see whether an AK could be accurized around some of the PPC's or the Grendel. There's also the 5.45x39 to consider.

 

[former naval person]

Re: Casing shape

He doesn't state whether he is looking at an AR platform or a bolt. In a bolt, taper won't matter as much. The AR itself is a limiting factor on accuracy. JMHO

 

[BlkExp98]

Re: Casing shape

I dont have a platform nailed down yet whether it be AR, AK or bolt gun. The AK idea would not really be an AK though because i wanted to test a different gas system. The bolt gun would be the most probable if i didnt do the AK. If i was going to go the AR route the 300 BLK would be my choice because of hearing bolts failing with 7.62x39 already and limited magazine options.

I know whats going to come with the AK but like i said it wont be a typical one and if i go that route it will be a long trip.

 

[Longshot38]

Re: Casing shape

This is a project I have slated for the future. My plan is to build a suppressed bolt action chambered in 7.62x39 and have it pushing a 200 plus grain bullet at subsonic velocities. I think it would make a excellent 200 yard rifle.

Also the 300 Blackout was originally formed from 221 fireball cases, at least in it's original wildcat form. But it is possible to use 223 Remington cases also and this what most people do.

 

[BlkExp98]

Re: Casing shape

Thats kind of what i thought too on the 7.62x39 chambering. I thought it would make a fun, low recoiling but accurate rifle. By chambering a .308 barrel for 7.62x39 i could load with .308 projectiles so i would have a load of options over a barrel made for the larger surplus bullets.

The 300 BLK is interesting in its the size of a .223 case but i just wonder if ill sacrifice too much velocity with it when im shooting supersonic. Eventually ill have a .308 suppressor but until then ill just be loading supersonic for the most part. I wonder if that new powder that yield higher velocity with not much pressure gain would fair with this?