Problem with Walker

[Will52100]

I got a new walker from Midway not long back to make a pair.  The problem is that after the first shot it starts binding.  Toward the last shot I'm rolling the cylidner by hand into battery.  I've got anouther one from Cabela's that hasn't had more than a 100 more shots through it.  It functions smooth as silk first shot to last.  Only differance in guns is the Cabela's is charcoal blued and the Midway gun is nitra blued.  I dought that's the problem! :eek:   As far as I can tell the head space is the same on both.  I cleaned it and lubed the cylidner pin with bore butter, both guns are treated the same, loaded the same, exc. but I'm having fouling problems with one.

Any ideas?