Reassembly question

[Pssst]

EDIT: Rubber mallet worked lol


I'm sure this has been beaten to the ground, I've tried searching but maybe my wording is wrong for the searches...

I'm reassembling my 17" BBS RS 262/263's I got new barrels(17x8) Old barrels 17x7.5)

My face will not sit flush in the 17x8 barrels, I'm not entirely sure what should be done to get them to fit properly... any insight would be greatly appreciated.

Thanks!