Cast Boolits And The AR

This relates to my previous post. I have been in contact with Anderson for a 7.62X39 AR upper. Their stuff is sized (SAAMI) for mil-spec but, there is a good chance my current SKS lead bullet round will chamber. I've never loaded for an AR shooting jacketed never mind cast. If my existing SKS load feeds and chambers and the throat is big enough to release the bullet - would shooting an AR with cast WW bullets .003-.004" over bore size be foolish? Before buying a second set of 7.62X39 dies and sizing bullets smaller I'd like to first see if the AR likes the same load as the SKS. The existing die set has been modified for large-for-caliber bullets for the SKS.

"there is a good chance my current SKS lead bullet round will chamber."

If so there will be little rise in psi shooting cast bullets .003-.004" over groove diameter. The cast bullet is sized down to fit the bore/groove diameter in the first bearing length of travel. That is very early in the rise to pressure curve. After sizing down the bullet acts as any other cast bullet would and does not there after create any more pressure.

This is determined from actual pressure testing in numerous cartridges using cast bullets up to .006" over the groove diameter including the 7.62x39 cartridge.

Thanks Larry. Not being AR fluent I didn't know the potential for damage if a spike in pressure made it to the gas block.

Cast boolits won't harm the AR barrel. Do you powder coat?

I shoot lead lubed with Lyman green in everything I own but don't PC. My concern wasn't with lead in the AR but the potential for higher pressure to damage something out of ignorance. If the chamber throat will allow shooting enough rounds to see if the AR likes the current SKS load then it's a simple matter to size subsequent bullets smaller for it. Back to powder coating, I have watched some YouTube videos (fortunecookie45LC?) but as of now nothings broken PC'd fix so haven't pursued it.