help with rings

Got a question or two for you pros.

I'm swapping a set of steel rings with a mate, he needs leupold mediums as his are too low. Looking at his low rings it looks like they have some plastic packer that goes in side the ring which is now fucked because he put some sticky crap on them, anyone know if replacement inserts are available? Otherwise I guess they useless as they slightly oversized without inserts or is 0.4 mm off 1 inch enougth to tighten securely? (~25mm dia. his vs 24.5 dia. mine)

Attachment 11306

Also are they Leupold brand or something else, slightly different looking than my old leupolds?

Attachment 11308

My Leupolds on the left for comparison. Think I answered my own question, stuck his on a scope of mine and they still seem to tighten well enough without whatever insert he had in them.

The rings in the first pic look similar to millet angle-loc to me

See here: Millett 1 Turn-In Standard Rings Matte Medium

Cheers ebf, that's the suckers!