herThanks for any help

take a "something" and spread them

you can use a pair of pliers, stick the head in and "open them up"

or use something like a crescent wrench handle. put a long something in then crescent wrench, and stick the handle down in there, and twist it.

this will widen the rails.

don't be scared, just get in there and spread em.

test the fit with bolt carrier only (no bolt, no FCG) it should slide freely.

take out the trigger group.

take off the bolt.

put the carrier in.

see if it slides freely the whole length

if it has friction anywhere at all (even a little) use something to spread it out.

I do this all the time. at least half of all builds have some friction somewhere, this hurt reliability