Stubtwist,
There is no 'performance' data from nearly 100 year old guns. We can only speculate. A.P Curtis was the plant manager and it was he who 'invented' and patented the second lockup scheme. I assume he thought it a better design OR because it was his invention and he was in charge. The third and last scheme was probably done to reduce costs. I have a 7E with the first design. I have shoot a few rounds of trap but have not and do not plan to shoot it to a failure mode. IMHO, the 'failure mode' of the Flues SBTs in the cocking hook and that rarely. Now only a problem because a replacement has to be made. There were about 5000 Fluse SBTs in use and they were very popular. That is my two cents anyway.
