delisle carbine like rifle in .300 blackout

[barnbwt]

but with the enfield i can customize the action length to what i need.. are there any other rear lugged bolt actions out there that'll allow me to do the same thing?

Why would you want to use a rear lug action for such a high pressure/thrust cartridge? You're begging for casehead setback and thrust issues (and SOCOM is pretty high in both departments if I remember)

TCB

 

[Jim Watson]

Got a dimensional problem.
.45 Win Mag is, like .308 etc., .476" head diameter.
It is .473" at the mouth, over a .451" bullet.
Seat a .458" bullet and the neck gets bigger than the head.
I guess you could make the chamber roomy enough for a reverse bottleneck.

There was a wildcat .458" revolver round based on shortened .45-70. The taper is very obvious at that length.

 

[barnbwt]

.45 Win Mag is, like .308 etc., .476" head diameter.
It is .473" at the mouth, over a .451" bullet.
Seat a .458" bullet and the neck gets bigger than the head.
I guess you could make the chamber roomy enough for a reverse

I wonder if the taper of the brass walls' thickness towards the neck on the longer brass might barely get him the rest of the difference? Only need 3 thou or so on each side, after all. Also, would there be any reason a 458 couldn't be swaged down to 451? (I have no idea how much force that operation would require, but it would seem to give you enough options even at the smaller dimension)

TCB

 

[justin22885]

my plan was to ream/trim the inside of the .308 brass after its been cut to length so the bullet will fit.. brass would be a tad thinner around the mouth than the rest of it but that shouldnt be a big issue, not for .006" difference, also it looks like this cartridge will probably be about 40,000 PSI as well since im basically going by .45 win mag specs.. theres really not enough case volume to shorten the case and increase pressure without saving at best a few millimeters over total length, plus if i did that it would put me at an akward magazine length

since i am going for the same COAL as a 5.56 cartridge, any action short enough for 5.56 should work fine, so long as i can put a 12mm bolt face on it, and there are a few AR-15 calibers that use magazines that should work well for this.. so, i can use front locking of a shorter action designed for .223 length cartridges

i'll need to add a .458 neck reamer to my tools when i start making brass for it

 

[redbullitt]

I like the 77/357 with a 10 inch barrel and a liberty mystic on there. The 44 is awesome too if you happen to have a can rated to take the pressure of 44 mags.

Both worth a look and far better than the 300 blk for these purposes IMHO.

 

[justin22885]

btw, im tailoring this load around an 8 inch barrel which shouldnt be too surprising, its basically a magnum pistol cartridge just loaded with an extra long and heavy bullet that also happens to sacrifice muzzle velocity down to a subsonic level.. 8 inch barrel, probably an 8 inch 45 cal suppressor with an extended shroud to give that integrally suppressed barrel look.. total length will be about 16 inches for the barrel

and 44 mag is only 36,000 PSI, thats not too bad at all, about the same as a 9mm

 

[LawBot5000]

It sounds like you're putting an awful lot of effort into reinventing the wheel, and I'm not even sure your approach will work. And even if it does work, I'm not seeing how your idea is more than a marginal improvement over 45 acp, which is a million times easier to pull off in an AR-15 (or any other platform for that matter).

If you want to get insane B/C in a subsonic cartridge (which is mostly useless, as many have pointed out), why not just load something like a 500 S&W magnum with 500-700 gr bullets? I'm sure you could get Contender/Encore barrels that would let you accomplish this and it wouldn't involve rolling a completely new cartridge from scratch. It would also have much better BC than your idea.