What is the largest caliber wildcat successfully built in the 375 Remington Ultra Magnum brass case ?

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I know of the .470AR, dewsigned by our own Jeffeosso.

George

Does it headspace on a shoulder or the case mouth ?

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quote:

Originally posted by Hammer:
What is the largest caliber wildcat successfully built in the 375 Remington Ultra Magnum brass case?

The .470 AR headspaces on the shoulder. However I believe the largest caliber to be the .500 MDM on the full length case.

the 500 B&M, the 500 Kill all .. i THINK the 500 cyrus ..

the 470 AR is the largest, that i know of, on the rum case, using a shoulder (Thanks George)

jeffe

To the best of my knowledge it is the 500 MDM. It is .500 caliber.
The cyrus is on the 338 Lapua case I think. The 500 MDM has a very slight shoulder on it.



Michael

Michael,

Very interesting photos! Is that the 550gr bullet in the last photo, loaded with the digital caliper? Also, do you seat all bullets to same cartridge OAL of 3.452” or do you seat all bullet bases to the “slight shoulder” neck junction?

Hi Jim

Yes that is the 550 in the last photo. No I seat most of the bullets up to the last cannelure that is in place, even though I do not have to crimp anything, this just happens to be where the round will chamber proper. I really have the shoulder, or slight (ghost) shoulder just a little too far to the rear, it should have been closer to the mouth. So I get the slightest bulge above the shoulder from some bullets. Diameter there is still smaller than the shoulder, but sometimes it is just not as aesthetically pleasing. As for function it has no bearing.

This cartridge is going to the field at the end of August to hammer buffalo in Australia. All these bullets with the exception of the 550 have been used in my 50 B&Ms with great success. Now we will just see what an extra 250-300 fps does.

Thanks
Michael

Hi Michael,

Very good info.

I just received one of Duane’s 5MX Mauser bottom metals last month that he slightly opened to the rear for me for a 3.43” internal magazine length. I trial fitted it to five of my M98 receivers and all but one would take an additional .050” from the front of the magazine well for a nice smooth fit without touching the lower feed ramp. Looks like the 500 MDM would work very nicely in one of them.

Hey Jim
That sounds interesting, however unless it's a Winchester I come up a bit ignorant! If you would like I can send you a couple dummy rounds and see if it would work???

Michael

quote:

Originally posted by michael458:
Hey Jim
That sounds interesting, however unless it's a Winchester I come up a bit ignorant! If you would like I can send you a couple dummy rounds and see if it would work???

Michael

PM sent. Thanks!

How many FPS do those 550 bullets travel. Just quiest.

jro45

My rifles are Win M70s with 21 inch barrels. I stopped at 2210 fps with the 550 gr bullets, 510 gr bullets 2320 fps, 470s at 2400 fps. That is enough and then some to do what I need.

My goals were to first and foremost, had to be on a Winchester M70, somewhat handy and portable for a rifle like this. So thus the 21 inch barrel and the rifles weigh in at 8.5 lbs. Next was .500 caliber since I have been working with .500s since 2005 in other cartridges. Next equal or exceed 500 Nitro. This cartridge and rifles did all that and then some.

Michael