Stan, You got a bad lot or they have thickened the rim subsequently. Over the past 2 years, I have been shooting Comp ones in about 10 different vintage English hammer guns, both internal and external hammer guns, with no misfires or rim thickness issues. They are 2 3/4" but the pressure is so low, I am not too concerned shooting them in 2 1/2" chambers. Recently, I have been shooting the ArmUsa 12ga 2 1/2" Vintage 28 gram loads available at Clays Ammo. They are the correct chamber length and the pressures are comparable to the comp ones. Pricing is good on those 2 loads. Us Non-reloaders are stuck with RST for anything below 12ga. with what I consider unfavorable pricing.
