300 blackout rimmed?

[adcoch1]

So I like to tinker around a lot, and last night as I was getting ready to load up some blackout, I noticed a lone nickel plated 357 brass on my bench. It was odd since I don't even own a 357, must have been my buddy from our last range session. Anyway, I was about to throw it in my random brass bucket, I decided to compare it to one of the 300 blk brass I had right next to it. Curiosity grabbed me, so I busted out the case lube, dropped my 300 blk dies on my handy Lee turret press, and using my 38 shell holder, developed the latest in tactical single shot wildcats! I give you the 300 blackout rimmed!

Shown next to a standard blk for scale, just a little short but still holds the bullet just fine. May need to find that chunk of 30 cal barrel blank I have laying around and try this out for a suppressed single shot... I love wildcatting...

 

[kcofohio]

A new cartidge is borned.

 

[Curator]

I have a MGM "Encore" barrel marked "221-300R" that is in effect a .300 Blackout with a rim. I bought.357 Magnum cases will work when run through the .300BO sizing die but end up a little short. Since I mostly shoot 235 grain cast bullets in this, I make cases from .357 Dan Wesson brass and trim to .300BO length. These shoot exceptionally well and don't have the occasional extraction problems of the rimless case.

 

[adcoch1]

I have a MGM "Encore" barrel marked "221-300R" that is in effect a .300 Blackout with a rim. I bought.357 Magnum cases will work when run through the .300BO sizing die but end up a little short. Since I mostly shoot 235 grain cast bullets in this, I make cases from .357 Dan Wesson brass and trim to .300BO length. These shoot exceptionally well and don't have the occasional extraction problems of the rimless case.

I knew it had to have been done before, and I thought that maybe 360 DW brass would work better. Glad to hear this is a thing. It just seems so perfect for a single shot to shoot suppressed with all the blackout data out there.

 

[edwardware]

Well, since .300 BO 'rimless' has the feeds-in-an-AR-mag market cornered, and there's only 3 guys with single shots left, perhaps you can get it to run in a belt-fed!

Just need to promote it as Ohio-legal, and equal to the .30-30 and .243.

 

[adcoch1]

Well, since .300 BO 'rimless' has the feeds-in-an-AR-mag market cornered, and there's only 3 guys with single shots left, perhaps you can get it to run in a belt-fed!

Just need to promote it as Ohio-legal, and equal to the .30-30 and .243.

Perfect...

 

[adcoch1]

Actually, the more I think about it this reminds me of a 32-20...

 

[Jeff H]

Just need to promote it as Ohio-legal,

I like the angle. It is (was) a pistol round so should be perfectly legal.

 

[brasscollector]

When you compare bullet weights and the velocity achieved from either they actually are quite close.

 

[gotboostvr]

Rimmed 300blk?

...so a 30-30?

Reminds me of the guy that loaded 223 sabots into a 300blk.

 

[adcoch1]

Rimmed 300blk?

...so a 30-30?

Reminds me of the guy that loaded 223 sabots into a 300blk.

Not quite a 30-30, bout a step down from a 30-30.

 

[Jeff H]

When you compare bullet weights and the velocity achieved from either they actually are quite close.

They shoot largely the same powder too. H110 is my go to 300blk powder.

 

[adcoch1]

They shoot largely the same powder too. H110 is my go to 300blk powder.

Yeah mine too. If I build a quick barrel for this, it is more in the Idea to share load data across different platforms. Like a good subsonic load in the ar 300 blk and the rimmed in a single shot. No other practical value, in fact it is going the wrong way when you look at brass price. Might just be better to get a 357 single shot instead...