In the famous Winchester Model 21 Proof Test, the NID failed after 56 proof loads, the Fox-Sterlingworth after 80. Of course the point was the overdesigned Model 21 digested 2000 proof loads and was just fine
I have never trusted a "Test" carried out soley by an organization selling a product. I really can see no "Over-Design" in the 21. It simply breaks on a hinge pin & has a single underbolt. The NID with it's rotary bolt, if properly fitted, is a "Stronger Design". The 21 was made of stronger "Alloy" steel, Period. Wonder how many NID rotary bolts Win smoked to "INSURE" they tested one which didn't fit up good?? Also note when they tested the Parkers, they picked the "Only Grade" which didn't have the sq shouldered doll's head. "UnBiased" I doubt it.
