Hello to everyone, first post other than my introduction post. I have a question. I just ordered my daughter a 20 ga. 11-87, compact model. I've done alot of searching on this site and many others, without a clear answer. She has trouble with her vision, and can see scopes and red dots easier than a bead or iron sites. The B-Square mount says 12,16 or 20 gauge with a sreial number including an "X or N". Problem is, I dont have the gun yet, and do not know if these letters will be in the serial number or not. I'd like to have them ordered so we can start shooting once the gun gets here. Thanks in advance for the help.