That is one long bullet... You never mentioned your twist. It would take a fast twist to stabilize that bullet.

I have some, never used them on anything. I agree with other posters that the lighter Barnes are the ones to use. With the smaller .223 case, even AI and .22-204, it would be hard to get much speed out of the 70 Barnes.

Maybe with a fast twist .22-250 or similar, one could work up a decent load.

If you're short on 70 gr. Barnes, I have nearly a full box. Send me a PM.

DF