Just bought a lightly used P220R on Gunbroker - mfg 2008-2009. Great condition (no apparent mods) and came with one factory 7-rd mag that functions perfectly. Bought three 8-rd factory mags, and none will insert fully into the pistol without slightly depressing the mag release button. It appears the upper lip of the mag is hanging up on the catch. After slightly depressing the mag release button, it feeds just fine and also ejects without any issues.

Suggestions?

My first instinct is to call Sig and potentially replace the mag release.

Since the 7-round mag works, do you see any wear mark near the mag catch slot? Have you tried just slamming the 8-round mag in? There is probably just a sharp corner that needs to be broken. I doubt that replacing the magazine catch will fix anything.

Could it be a "new higher cap mag" issue solved by leaving it loaded for a few weeks?

Also, check the mag catch engaging slot on the mag for any burrs.

Loaded with eight rounds, my new WILSON magazines would not seat in my 1911 pistols, either. They worked fine with seven rounds.

I loaded them up with eight rounds and let nature take its coarse with the springs. A few days later they work just fine.

Look at the front of the mag opening at the top and see if there is a beveled/taper where the mag release rides the magazine of the seven rounder.

The newer mags may not have this bevel/taper and rest against the mag release base as opposed to further out of the mag release. you may need to modify the eight rounders.