7.62x40wt Brass

[gunsandgunsmithing]

With the introduction of LT-32, Larry Feusse's 30 Gorilla and Robert's 30 ARX 40 improved are very interesting in a bolt gun. My best load in my 30 Major benchrest rifle is 34.7 gr of LT-32 pushing a 115 gr 10X custom bullet at 2953 FPS. It is, however, a PITA to load. Even at a dead slow trickle, it completely fills the case. Would love to get the powder column about 1/2 way down the neck so that the bullet just seats on top of it.

Disclaimer: I don't know anything about an AR. Just started shooting one in a deer/predator context.

But, in my 30 Major AR, cut with my 30 Major benchrest reamer, I have space left using all the H4198 that I care to use.

Yes, as mentioned in the other thread, the limiting factor is the ar15 platform, at least with standard bolts and barrel extensions. You should have good luck with the lt32 and 4198 in a 30 Major, but certainly not at the same pressures. About 50K psi is the upper limit with the ar15 and the .443 bolt face. The 223 bolt face generates less bolt thrust, so pressure can be higher with a case based on it.
I'm pretty certain the same would apply to the one Rob is marketing.--Mike

 

[Tim Singleton]

Tsingleton

I have some unfired 7.62x40wt brass made from .223 brass so I estimated the water capacity based off the unfired brass I have, because the brass blows out a little in diameter at the shoulder when you fire it. The unfired brass I have is about 28 gr. water capacity and I figured when you fire it, it would be around 29 - 30 gr water capacity.

Do you happen to have a measured water capacity for brass that has been fire formed?

I would be interested to know what you get if it's not too much trouble.

Robert

I filled and weighed a fired un sized case 3x the average weight of water was 30.2 gr

 

[Tim Singleton]

My load is 26.8 gr AA1680 with sierra 125 hunters 20" barrel 2540 to 2550

 

[rcw3]

I filled and weighed a fired un sized case 3x the average weight of water was 30.2 gr

Thanks!
Robert

 

[Tim Singleton]

I am somewhat interested in the (some) .30 cal AR based cartridge of some sort. Why, I don't know...I can't hunt in PA with it, however I would like to take a trip to TX for a hog hunt. Whitely's 40° version looks pretty cool, but I am not a taker of the .443" bolt face in the AR, mainly because they don't make one in LH. I have gotten to the point in life where I just refuse to shoot a right handed gun dang it! I may have to develop one on the 6.8 case just fer fun.
I made a sizing/trim die for a Dillon trimmer about a year ago which will allow me to produce about 600 .300 BLK cases per hr from .223 brass. Again, I don't know why, I don't have a .300 blk, but have built several for customers.
I too, am not interested in shooting expensive heavy bullets at a subsonic speed through a suppressor because I am pretty sure that I am probably not going to get a phone call from Seal Team 6 any time soon to lead them into a clandestine mission, so I would go after terminal energy at any decibel level.

JS

JS
Here is a link to a .30 cal based on the 6.8spc.
Like the 30Gremlin 30Major 30ARX
If you can think of it. Someone else probably has as well, and may have most of the ground work done.

The 30HRT is pretty tough
http://www.ar15.com/content/page.html?id=647

I'm not sure it offers anything above the 7.62x40. Different bolt and mags required as well as brass