by error I ended up with a box of 450 gr North Fork Cup Nose Solids instead of the 350gr I ordered.

Seeing that I have them in hand, has anybody ever tried loading these in the 45-70 Marlin / Winchester

I have H322 & RL-7

Thanks

Depends on what you are hunting, but many up in Alaska and elsewhere load the heavy 450gr all the way to the 540gr Garrett Hammerhead in the 45-70. It's not a long-range rifle anyway, so might as well load up on bullet weight. Elmer Keith will be proud! :-)

As a matter of fact, I have loaded the 450 grain NF FPS in .45-70 and 45-90 to be fired in Miroku/Winchester 1886 45-70 and .45-90 rifles. This was very succesful and the penetration was impressive. The loads were on the "warm" side and should be worked up to carefully. These bullets were from a special run made to chamber in the 1886.
We also loaded the 450 grain Kodiak heavy jacket FMJ, but for maximum velocity fell back on Grizzly cartridge for the final African loads of this bullet. It has shot through everything but ele skulls, stopping when reaching the brain and knocking down but not killing. The NF FPS and brass Punch bullets then shot through, finishing the job.

This was documented at length over on Leverguns.com in 2009. H322 was first used on some of the loads, but I have since been pleased with VVn133 and TAC. Rl 7 should do very well too.