I’ve been picking up parts for a 700 Mountain rifle for a year or two, I’ve got a walnut stock, SS bottom metal, a SS 7mm-08 Monuntain rifle barrel and I bought a new action here a week or two ago. I’ve also got the same barrel in .260 Rem, but I think I’m going with the 7mm. All I’m missing is a barrel lug and I’ll have a Mountain rifle for just a little more than I could’ve bought a new one for...
Which barrel lug do I need?

Most factory Remington are somewhere close to .187”. You could use a factory or buy an aftermarket one.

OEM Rem thickness is 0.186”. PTG has a variety of thicknesses and designs, square or tapered. Cheaper to buy directly from them and to go with one of their stock thicknesses.

If you have something specific in mind PTG, and a number of others, will make it for you.

I bought one from Darrell Holland a while back for a custom build. He claims his are better. They are thicker for sure.

Regardless of which lug, it needs to be checked for headspace. The markings may not line up, if that bothers you. Some aftermarket lugs are bigger which means the stock inlet will have to be adjusted for fit. The Holland lugs are good, they are ground, but if you aren't truing up the action, it doesn't matter much.