223 wssm 10 twist

[Elk Wallow]

Hey guys I have a Winchester m70 in 223 wssm with a 10 twist barrel. From what I can gather I’m only going to be able to shoot up to a 69 grain bullet. Probably going to try 69gr. TGK’s. Anything heavier has twist rate restrictions.
Is it possible to maybe shoot heavier bullets since it is a faster cartridge? Hornady is showing 36-3700 fps for 75 grain bullets. I live at about 3000ft elevation.

Thanks for any info, Kevin