I was wondering if anyone could provide me with information on this wildcat conversion. My buddy wants to set up his MRC PH action for something along these lines. I thought I'd poll the group on where to find more information. He thinks he can get 3000FPS with a 500grn bullet? I'm sure its already been done I just haven't found much on it.

Thanks Brad

the smallest I have seen is what people call the 475 Royale. I have a set of standard 475 Gibbs reamers here, that just neck it down with no changes. You would be looking at a 20% increase in case capacity over the 460Wbee. That translates into a velocity gain of 1/4th that. Figure an extra 150+/-fps over the claimed 2700fps of the 460.

Rich
DRSS
Knowledge not shared is knowledge lost...

Thanks for the info. I'll pass it along. I'm trying to talk him into a 585 BHE but, he wants something more useful in 458. I personally like the 458/416 Rigby wildcat idea (good cheap brass and still .458) He thinks my 7.5lbs 416rem kicks a bit. I love it I'm still waiting on my RSM 500 Jeffery conversion maybe this will motivate him to build something bigger.

Thanks Brad

If he wants a bullet at 3000 the 585BHE
will get 600-650gr there.Ed

If the Gibbs with high pressure brass won't push a 525 gr bullet to 3000, then its unlikely you can really get a 458 500 gr bullet there either.

But if your friend wants to try anyway, make sure he knows to buy 505 brass designed for the full pressures required. I know Bertram won't last long enough to develop the loads.

I can't speak for Norma because I haven't seen the specs. Sometimes people comment that it is soft but I never use it so I can't confirm that.

Jamison brass would be the way to go if the 458/505 is the plan. You can get it from Neal at Custom Brass and Bullets.


There is also the 416/505. (I have the reamer; so I can't say much bad about your buddy's idea) but I've never built one. That may end up the plan for my PH. Actually, a switch barrel with 550 Gibbs too.

.458 is the only bore between 338-510 that I haven't seen the 408 Chey-Tac wildcatted too.

420g at 3000fps in the original .408 configuration.