I have a few............. The M1 is a fine wepon....not much use unless your hunting or target shooting or something. No uses IMHO as a home defence wepon.
I'm not a fan of Glocks - I love my Glock 27 though so I may be converting a bit - the 23 is the full sized version of mine.
I have never returned anything to a gun show but around here they usually do not allow it, might not be the case with your dealers. Reason being the local dealers around here are at gun shows to shed alot of inventory quickly, if they took returns at the show they wouldn't have time for the mass of people at the show buying. If you have a receipt and the dealer is local go and check out his shop and take it back there, I don't recomend bothering tem at the show.
Also make an effort to get to know the gun shops in your area and find one where you like the sales people, that way you can ask questions and have confidance in the answers they give you and if your a regular customer they are likly to get to know your abilities and hlp steer you to guns that fit your needs.
oh yeah and like aquariums guns are addictive, I refuse to count my collection
and unless I have plenty of disposable income I can't let myself go to guns shows as I always end up walking out with something new.