Steel Ammuntion? In my AR?

[Clint]

Well, I decided I would test this theory, and pulled five Tula bullets and replaced the propellant with 24.5 grains of benchmark, and loaded five rounds in brass cases with the same load.

Full report later.

Looking forward to it.

These test rounds were shot alternating brass and steel, about 10 of each at a time.

There doesn't appear to be any increased fouling on the steel cases.

Attachment 41626

[pezboy]

Actually, the 5.45mm x 39 is not as tapered as you think. The angle of the side wall for a 5.45mm x 39 case is only 0.03 degrees more tapered than that of 5.56mm NATO.

There are two things that kill the reliability of steel cases, one - the heat treatment of the case, and two - how well the case conforms to the required dimensional specifications, which are not necessarily the exact same dimensions as for a brass cases.

I believe 5.56X45 has a 1 degree taper, 7.62X39 has a 2.7 degree taper, and 5.45X39 has a 1.6 degree taper.

[lysander]

I believe 5.56X45 has a 1 degree taper, 7.62X39 has a 2.7 degree taper, and 5.45X39 has a 1.6 degree taper.

The is an extra zero in the quoted post. The difference is .3 degrees, and that references the side angle, not the total included angle.

The drawing specified taper per inch on the diameter (taper/inch is just the tangent of the body taper angle) for the various cartridges:

5.45 x 39 - .02800 TPI
5.56 NATO - .01746 TPI
7.62 NATO - .01200 TPI
7.62 x 39 - .04688 TPI
.50 BMG - .03220 TPI
14.4mm x 114 - .01815 TPI
25mm x 137 NATO - .02500 TPI