This is a really big case... No belt. Rebated head. It appears to make maximum use of a Remington long action. Huge appetite for powder, and has the ability to toss heavy bullets pretty darned fast. Tried some Remington factory loads first, 200 grain Nosler Partitions. Over my CED Millenium chronograph they averaged 3190 fps, with a few topping 3200 fps. I can live with a .30 cal, 200 grain premium bullet at 3200 fps...
Accuracy was okay, but nothing to write home about. Despite the 26" barrel, this is a sporter-weight rifle, not a heavy bench rig. Recoil is substantial. The CDL stock design helps as does the very nice Limbsaver recoil pad installed by Remington. I adjusted the trigger to a nice crisp letoff, and installed a 6x Leupold in dual-dovetail rings. The rifle has not been bedded. The stock appears to have two crossbolts. Started handloading with standard RCBS dies. Priming the big case was interesting, because it doesn't fit in a standard Lee Auto Prime, without modification. Rather than carve up my Auto Prime, I bought the RCBS primer tool, pretty nice piece of gear although we had our teething problems.
Based largely on what I'd been told by others who've loaded the .300 RUM, I selected the following components: Rem magnum primers, Hodgdon Retumbo powder, Sierra 200 gr SPBT bullets, Nosler 200 gr Partition bullets and 200 gr Accubonds. So far I've only loaded the 200 gr Sierras.
I've gone up to 95 grains of Retumbo - which is nearing the max from Hodgdon's data. My handloads have broken 3100 fps, with a 200 grain bullet without any excess pressure signs. At 94 grains of Retumbo I'm seeing an average of right about 3050 fps, and three shot/100 yard groups are amazing to me... Often I'll get two bullet holes actually touching, and the third not far removed. I don't shoot it more than three shots at a time. The slim sporter barrel gets hot in a hurry, burning 94 grains of powder at a shot, and I need a break too.
I am considering a muzzle brake for this rifle. Haven't had one in the past, but have shot a few braked rifles - and they do indeed tame the kick of powerful magnums. Also considering a good laminate stock, as this rifle is destined for some high-country hunting in rough conditions and rough weather. I didn't hunt with it last year, as I hadn't gotten very far along in load development, but this year I suspect it will be my primary rifle for black bear, elk and even mule deer. It's a thumper on both ends, but accurate and easy handling.
Regards, Guy
Hold 'em & Squeeze 'em