TargetTalk

Does anyone know what the twist rate of the GT9 9mm pistol is? I am still trying to find a good load for my 6-inch GT9.
I am now suspecting that the twist rate is slow, and that a light bullet will stabilize better. By looking at the barrel rifling the guess would be that the rifling is about 1 twist in 24 inches.

Take a cleaning rod that has a handle that rotates freely, and put a patch on it that's tight in the barrel. Insert the rod from the muzzle and push in almost to the chamber. Take a piece of masking tape and make a "flag" on the rod right flush to the muzzle. Using the handle, slowly pull the rod towards the muzzle until the flag has made one complete revolution. Measure the distance from the current position of the flag to the muzzle - that's your twist rate. Since it's a pistol, the flag may not get to make a complete revolution in the short barrel, so you may need to figure out the rate from a half revolution.

In the 6 inch barrel, of which about 5 1/4 inches are rifled, the rod turns only about 1/4 turn.

dragon wrote:In the 6 inch barrel, of which about 5 1/4 inches are rifled, the rod turns only about 1/4 turn.

If the rod rotates exactly 1/4 turn in exactly 5 1/4 inches, then the twist rate is 1 in 21 inches.

Pardini states that the twist rate is 1 in 450 mm ( 17.72 inches ) This is for the rifled barrel, and the twist rate of the polygonal barrel is 1 in 10 inches.