I have been looking for the hard cast bullets with gas checks for my 470 NE.
I found Mountain Bullet Works web site...
I noticed the dia. of the bullets are .475 - .476 is that a concern for a 470 NE?

John...First off I am so ignorant about the .470NE that I had to look up the groove dia...I found .474"...Is that correct?
Also I don't own a double...but I do shoot cast..

Conventional wisdom when using cast boolits is to size .002 over the groove dia. of your rifle...I have found that I get better accuracy sizing my boolits just small enough to fit in a fired,unsized factory case**(see below)..That way you have enough room for the case to expand upon firing and release your boolit and you have better boolit to bore alignment which is one of the factors crucial to accuracy firing cast..Next thing to do is make a dummy round and see if it will chamber...If it does then you are good to go....

So how do you get there from here?(I assume that you haven't ordered the Mt. Bullet Works cast boolits yet)..Take one of your factory loaded fired cases and a 470NE jacketed bullet and wrap it with one wrap of scotch tape then see if it will fit into the fired case by hand...That one wrap of tape should add .004" to your jacketed bullet diamiter...If it fits into the case then the .475" - .476" cast should work...But I bet that a boolit even larger would shoot better if it would fit your case and chamber...

**from above: My experience
Last spring I bought a Ruger #1K-A LTD in .35 Whelen for shooting cast...My largest .35 caliber molds gave me .360-1 dia. boolits...My throat was .362" and my groove is .358..very close fit by conventional thinking on shooting cast...
At 50 meters my groups were running 2 1/2 to 3 1/2 inches...made me sick!...One day while staring at my loading block full of fired brass I reached up on the shelf and pulled a Speer 270gr. 9.3 jacketed bullet out and seated it by hand (barely) into the fired Whelen case...Hmmmmm...Then I honed out my .361" push thru sizing die to .364" sized up some 9.3 (.368") cast boolits and ended getting the first 4 in .70" and 5 in .91"...

Good luck and have fun!.....

I shoot a lot of .475 cast bullets in my 470NE double. Good accuracy with no other issues.

Jim,
Which bullet manufacture are you using? Do they have gas checks? Are you having any problems leading your barrel? Do you have any loads worked up?
I have just cleaned, sized and primed 200 cases… I’m ready just needing a little help with the cast bullets.
Thanks, John

Low Wall thanks for the post!

I will check with my gun shop on the brand. Yes they have gas checks. I do load them down to prevent leading. will be back tomorrow.

I have shot a lot of cast bullets out of my 470's,no issues whatever,the bullets that I used were Cast performance & MT.Baldy,all were gas checked & hard cast,I have shot full house loads with these bullets & hunted pigs often with good results,I always make sure to clean my barrels well though when switching between copper & cast.

Laser-Cast makes a GC bullet for the 480 Ruger.
1-800-811-0548.

Rich
Buff Killer

375jon. The hard cast I have been using were purchased from Huntington Supply. Not sure who make them.

I use them for a light load and use 48 grains of 5744, no filler. I have used 86 grains of Rel 15 (2100 fps) but had to deal with severe leading.

I did chrony this load a while back, around 1600fps as I recall.

Good Luck