I had some accuracy issues as you describe with a well used and worn G34 I purchased from another shooter here in AZ. I am not bragging, but I am a ferly damned good pistol shot, and this '34 wouldn't shoot as I thought it should. My Glock 26 would shoot circles around it.
It was enough of a bargain at $350 with 6 mags, that investing another $160 in a Lone Wolf barrel wasn't out of the question.
As soon as I dropped the new tube in, the gun went from 7"-8" at 25yds to 3"-3 1/4" at the same distance offhand. Off the bags it would tighten up to 2 1/2 - 2 3/4"....IF I was doing my part.
OTOH...if you want shut of it....get an XD.