look at the bottom of the barrel mount. type A has no slit so it's less adjustable according to your barrel diameter versus that of type B. It also looks like with type B, you'll have to modify your barrel with cross notches for the screws to fit. (give a sturdier fit and is less likely to rotate on you)
Take a look at your gun where the stock front sight is. If there are notches on the outer barrel, you can use type B.