We discussed this in another thread a while back. Not about anti rotation pins but it may help.

The OE 15-22 (and std AR-15) pins are .895". The Geissele Colt 901 pins I have measure .995". The 15-22 lower is ~.990" wide at the pin holes.

That means the 901 pins will "stick out" ~.003" on each side. The original pins sit ~.050" recessed per side.

To put .003" in perspective, an average human hair is ~.004" thick.

1" = 25.4mm