I’ve got an M70 in stainless where I’ve lost the front stud. I have a blued one in it now but I’d like to put a stainless back.

It is a machine screw style so it’s a simple matter of getting a new one and threading it in.

Where is the best place to get a quality part? I know it shouldn’t make a huge difference but I’ve bought some real crap from China Kn Amazon so I’d rather skip that. I’d like to match it somewhat.

Go to your LGS and look for an Uncle Mike's sling swivel stud kit. They have stainless/nickel ones. Find one that looks to be about the same length and buy that one. Or you could buy just the stud and nut on ebay:

Uncle Mike's sling stud

You'll have to cut that one to the appropriate length.

I'd offer to send you one, but shipping would cost as much as the one I posted in the link from ebay.

HAHA...Yes, it would. I appreciate the sentiment, though, nonetheless. That's the tough thing about buying tiny parts online....."1 dollar screw plus 10 bucks shipping"....LOL.