Want to hold up to 50 rounds of ammo conveniently? These flip top boxes are available in five sizes to accommodate any type of handgun ammo. They are stackable for storage feature an easy-to-grip textured surface and come with a load label. P-50-38 Cartridge Sizes 357 Rem. Mag. 25-20 Win 30 Mauser 32-20 Win 327 Fed. Mag. 35 Win. S.L. 38 Spec. 38 Auto Colt 38 Super 38 Short Colt 5.7x28 FN 7.