Texan carbine/horrible accuracy

Benjamin Bulldog .357..had mine converted to Pitbull carbine .357.( 30" inches overall length, m18 threaded, use a re-wrapped Donny Fl Emperor v3) get about 272 ft lbs and less than a inch at 50 yards with 158gr swc hp Hornady slugs..But, im thinking of a Hunter Supply Texan .357 for Loooonng Range..or a LSS .357...had a Western Bushbuck .45 ordered the other day, decided it would disturb the neighbors so i cancelled the order..So now, decision to make on the HS Texan .357 or Texan LSS .357.. my Gauntlet 30sl is perfectly good for 400/ 500 yards max on ground hogs and plinking and id say for deer at wherever i could hit them in a lethal area( say 100 yards)..hell, with my new Huben gk1 v3 .22 id pop a deer in the temple at bow ranges( this little power house is Lethal with slugs)..but im a veteran shooter of 40 years..
 
No moderator. I have been shooting off a lead sled. My slug weight is 330 grain. I’m going to try and inspect the barrel to see if there’s anything obvious tho I’m new to barrel work.
Some guns dont like to be shot like that. Try just shooting on a bag resting on your hand and see if that helps. My texan carbine does not shoot well on the mounted bipod.