Home Forums Hunting & Shooting Hunter's Campfire Getting to fire a wildcat!

Ben at Hornady named this wildcat 6.5RUMLN. I asked him what that stands for. He told me six point five Remington Ultra Magnum Long Neck. The neck is about .350" long.

Fired case water capacity – 109
Fired case powder capacity (not a load) – H870 – 108.5

Maybe someone can tell me what a safe load is for 120 Barnes and 142 Matrix.

While waiting for the form dies from Hornady I became impatient and tried an experiment. I made a “washer” looking thing to insert on the top of a 7RUM unfired case. The outside length or thickness of the washer is about .090”. The outside diameter is .520” so it won't get stuck in the die, and the inside diameter is .340” to clear the neck with lots of room. The angle on the top of the “washer” matches the inside of a .300 RUM full length sizing die; which is 30*. The inside angle is about 28* and starts at the bottom of the .090” side and goes to zero at the .340” dimension. After lubing this on the inside touching the shoulder of the 7RUM case and lubing the 7RUM case I s-l-o-o-o-o-w-l-y pushed it into the .300 RUM die. I measured the shoulder height until it was barely under 2.385”. Then s-l-o-o-o-o-w-l-y I pushed it into a 7RUM full length die; off of which I trimmed about .100”. Often I took the shaping case out to measure the head to shoulder dimension. When it matched the chamber cast I necked it to 6.5 and tried it in son John’s Savage. I had to push the shoulder back a few thousandths and try again a couple times. Once I could close the bolt on the sized case I locked down the die.

Then I loaded and fired it. It worked. I fired one more and sent the two cases and the chamber cast to Ben at Hornady to make a set of loading dies. The 7STW case I have holds 100 grains of water so I chose a load based on that case. I arbitrarily chose 73.0 grains of Retumbo behind a 129 grain Hornady. The primer was a Federal 215.

I'm still waiting for my 6.5RUMLN on the Pierce action and carbon wrapped barrel. The MPI stock had to be completely inletted and fitted with pillar blocks and whatever else a gunsmith need to do when starting from scratch. I did take him a 142 grain Matrix dummie cartridge that fit son John's rifle to use for setting up the magazine and feed rails.

Enough of this waiting. It's time for some shooting!