Unless you paid for or were otherwise offered some kind of special warranty, Bud's owes you nothing. Basically, your option is to keep sending them back to Kahr until they properly repair them or they may opt to replace them.
One thing to keep in mind. Are you sure it is the guns? Are you the only one that has tried shooting them, or have you had several people try them out to replicate the problem. Believe it or not, some people cannot shoot certain guns. Also, have you tried different brands of ammo, both before and after the warranty work? What did they say they did to the guns for repair?
What problem are you having with the guns?