I have been fighting vertical stringing with my Handi rifle barrels. I have "floated" the barrels with "O" rings and tried different amounts of tightening on the forearm screw. It has also been suggested that the forearm should be tightened and then add 2 more turns. That is very hard to do with a synthetic forearm. I tried to tighten to 60 in-lbs with a 1/4" drive torque wrench, but the screw just wants to pull through the synthetic material.

With multiple barrels, the POI will change if the screw isn't tightened the same amount each time the barrel is changed.

The best groups so far have been 200 gr Sierra JSP with 14.0 gr Lil'Gun in the .357 Mag barrel (1 1/4" at 100 yards) with the screw snugged down and then backed off 1/2 turn. The .223 will shoot a couple of loads at around an inch at 100 yards with the screw backed off 1/2 turn. I don't know that any of these groups are repeatable unless I just happen to get the tension on the forearm the same as before.

Any suggestions?

Paul when you shoot from the bench with these guns you have to be careful of the forearm taper, if you shoot from a rest make sure the rest is back close to the reciever other wise when you pull the trigger back the gun could slide ever so slightly rearward thus dropping down slightly and thus causing a vertical string , me personally I shoot from bags filled full with shelled corn and keep them behind the forearm screw to eliminate the forearm taper. Given all of that what are your worst groups , 1 inch out of these guns is not that bad.