Hi Ya'll
I got some brass last week at a gun show a buddy had picked up it has REM-UMC 300 magnum. Is this stuff weatherby brass or is it something specal forces used?? ive got about 35 rounds of it. Didnt know if it was something specal or not. RayA
_________________

Compare it to a 300H&H case (IIRC that's how Rem used to stamp it). However it could have also been fireformed into the Wby or a host of other chamberings, considering that the H&H brass is the parrent case to most of the belted mag's (400-375 H&H being the origional BM)

Hi Tailgunner
Well after sizeing it up its almost 300 weatherby buttttttt not exactly same dementions the books show and next to weatherby brass you can see the difference. I didnt know if it may be a specal sniper round from yr's ago or what.Finding any info on this ones been frustrateing at best.

Well, there was a 300AMU, but that was simply a 300H&H case loaded for the Army Marksmanship Unit (match load). Or it could be a 300H&H Improved.
Perhaps you can find dimentions, drawings or photo's over at www.reloadbench.com Greg (the owner there) has quite a few listed in his data base. Another place to look for dimentions is the Clymer Reamer website.
You could also post the dimentions here, to see what we can come up with.

Thanks again Tailgunner
I'll check over there and see what they have to say. i get demintions later tonight and post them . RayA

Hi Tailgunner
well I got some measurements and things aint addin up at all. these factory sizes are for 300 wetherby

case length 2.825 Fac these 2.802-2.812
case length to shoulder 2.292 these 2.447-2.451
neck Length .327 factory these 3.80-3.881
and the mouth of the case measures .337-.338
instead of .308. Iam not sure what ive got here LOL. RayA

There are some diameters that would help narrow it down (personaly I think it's a wildcat). 2.80 is the nominal length of some Lorenzzi cartridges, and also the Peterlongo x71mm cartridges (but they arn't belted). After tonight I won't be near my referances (poor as they are) until next friday, so stay patient.

Radiused or sharp corners at the neck/shoulder?
Rim diameter
Base diameter (ahead of the belt)
Shoulder diameter
OD of case neck
I'm assuming your measuring the inside of the mouth, so at a guess it's somthing in the 32 / 8mm / .338 range

The good news is that they can be resized to 300 Weatherby if you wish to do so (if you want to get rid of one, I'd be interested in having one).

HI Again TailGunner
Well the case is magnum belted same size as the 300 weatherby.iam thinkin yer right. ANYBODY need any wildcat brass? LOL RayA

I'm always interested in wildcats. Email me at ereynolds30@comcast.net and we'll discuss cost.
Regards,
Ed

Ray I picked up 6 boxes of the same brass. It is 300 Ackley improved brass or 300 H&H improved. I believe it was made for target shooters. I am in the process of putting a barrel on P-14 action I have sitting around.

It's sounding like you guy's have picked up some 300AMU (Army Marksmanship Unit) brass, which is a 300H&H Improved

quote:

Originally posted by Tailgunner:
It's sounding like you guy's have picked up some 300AMU (Army Marksmanship Unit) brass, which is a 300H&H Improved

Or a 300 Ackley Imp.

Or the "300 Mashburn long"... or any of several other "improved" 300 H&H's , Ackley wasn't the only one that improved things. (actualy the AMU is shorter than the 300H&H, my bad).