44 Warp - rimless 444 marlin

[elwarpo]

So the project I have been working on is a large bore round for 308 rifles. I noticed the 444 marlin and 30-06 cases have almost identical dimensions (except for length). So if you straight wall a 30-06 case and cut it down to the 2.225" of the 444 marlin, you can fit 44 cal bullets. The best part is you can use cheap 30-06 brass for a starting point, 444 Marlin dies, and the rim diameter and rough overall length is the same as a 308 so no other modifications to an AR308 (or other 308 rifle) than the barrel. You even have the same mag capacity as 308. It is also slightly tapered which helps extraction.

It headspaces on the case mouth (like the 30carbine, 45 ACP, 45 Raptor...) so overall length is important.

So I decided to go forward and have Dave Manson Precision Reamers (here in Michigan) make me a custom reamer. Sent the reamer to McGowan Precision Barrels to have a 44 cal blank turned into an AR10 Barrel (DPMS Extension). Picked up a Aero Precision M5E1 kit (FDE Lower, Upper and Handguard, NIB bolt, LPK and Buffer tube), Radian Raptor Charging Handle, Odin Works Mag extension, Magpul SLS stock and pistol Grip, and a Vortex Razor red dot sight.

The 444 marlin is an unrecognized cartridge, but it will put a bullet out faster and shoots flatter than the other big bore cartridges (45-70, 45 raptor...) due to the higher ballistic coefficient of the narrower bullet. Because it was designed for lever guns it does this at a much lower chamber pressure than a 308 (42,000 versus 62,000 of the 30. In a AR 308 I foresee even higher velocities as the pressure approaches 308 levels, but I plan on staying at 444 pressures as a safety measure.

Typical 444 Marlin/ 44 Warp velocities expected are:
240 grain 2450 fps
265 grain 2300 fps
300 grain 2200 fps
405 grain 1800 fps

My goal is a 405 grain bullet at 1050 fps silenced as a short range quiet thumper round). I thought of the round when I saw police officers entering a building with AR 15s and shotguns. I figured that a metallic cartridge with the ballistics of a 12 guage and the capacity of an AR15 would be a lot better for entering a hostile building. I do not plan on patenting this, just let anyone use the idea.

Finally here is some mocked up rounds showing 240 and 280 bullets seated at the same depth. Final rounds are awaiting the barrel to be finished for proper fit (based off 8mm Mauser, so the rims are slightly different, 30-06 brass is on the way). Left to right 308 hunting round, 7.62x51 mil spec, 44 Warp with 240 grain bullet, 44 Warp with 280 grain bullet.

[hartofthethumb]

Wow! Coolest thing I have read in a while.

In an AR style rifle that round would be a lot of fun. A good friend of mine has a .444 lever gun. I have always thought it was an underrated round, ever since I first got to play with it at the range and then did some reading on it's ballistics.

[dirtmcgirt76239]

sounds cool elwarpo. Did you mean underrated or under appreciated, not unrecognized ?

[elwarpo]

sounds cool elwarpo. Did you mean underrated or under appreciated, not unrecognized ?

All of the 3, but mostly unrecognized because people do not know it exists.

[elwarpo]

I am also thinking of a shorter version to be used in an AR15, sort of a slightly lower power 458 socom, but made from cheap 308 brass. It will also be shorter than 1.8" so ok for hunting in MI. going to mock up a bunch of casings to see how many fin in an 30 round AR mag. Think of it as a 300 BLK on steroids, but uses a 308 boltheas (same as used on the 458 socom.)

[dirtmcgirt76239]

hmm you make a good argument or case for it. Why has no one else done this ?

[elwarpo]

hmm you make a good argument or case for it. Why has no one else done this ?

Well it sort has been done, the 45 raptor is similar, and there has been many straight walled magnum cartridges using belted cases for headspacing. They work great in a bolt gun, but I wanted a semi auto. I really like 458x2 american, but it is rimmed also.

[Ol` Joe]

Well it sort has been done, the 45 raptor is similar, and there has been many straight walled magnum cartridges using belted cases for headspacing. They work great in a bolt gun, but I wanted a semi auto. I really like 458x2 american, but it is belted also.

FIFU

[elwarpo]

450 Bushmaster is another similar round, this one is based on the 284 case shortened to 1.7" for an AR 15. I really think they should have gone to .458 for a better selection of rifle rounds. In effect an rimless 45-70. That will be my next project.

[Ol` Joe]

450 Bushmaster is another similar round, this one is based on the 284 case shortened to 1.7" for an AR 15. I really think they should have gone to .458 for a better selection of rifle rounds. In effect an rimless 45-70. That will be my next project.

To go to a 458 you would need a fatter case then the 284 used for the 450 Bushmaster. The case mouth diameter of a 458 win case is .481" tapering back to 0.5130" in front of the belt. The same with the 45/70, mouth diameter is 0.480" tapering to 0.5056".
The 284 case at the shoulder/body junction is 0.4748" tapering to 0.5008" at the rear most point. The case body then is fatter then the rim which is rebated down to 0.473", the standardized rim size of the 30-06/308/ family of cases. The 308 as example is .4539" at the shoulder/body junction. This is much smaller diameter then the other two cases and allows for handgun bullet which is 0.452" diameter to fit in the case body and keep it straight walled. I am not aware of a rimless case with a body that would allow a full diameter .458" rifle bullet to seat and keep the case in a straight walled configuration. The case bodies are either too narrow or they are too fat, which would be OK if you want a bottle neck design.
Keep in mind too as you cut back a case the walls taper out becoming thicker. This could result in a wasp waisted cartridge depending on the case, the taper, and the depth the bullet is seated into the case. You see a little of this type of shape in pistol reloads at times as the dies resize the case walls down below the factory diameter then the bullet expands it out as it is seated and in the 2 cartridges on the left of the picture you showed in your 1st post but more pronounced.

Since you are going to be trimming or other wise altering a existing case for your experiments, why not just cut the 458 case down to whatever length you want and turn the belts off? You could have it headspace on the mouth this way, be rimless and be whatever length you want.