Brent: I found at least some of the discussion. Apparently the decision was made around 2004 to do away with duplex loads for the Creedmoor style long range shooting, some horror stories along the lines of 'if a little is good, a lot is better' doing damage. I had remembered something about a 10% rule, but it apparently was 25% at one time. I didn't find any specific reasons given for the change.
As for the Borchardt question, I think I saw that exposed hammers were specifically called for by the NRA in the rules they set forth, could not find any reasons given. Apparently B's are OK for long range.
Please don't get me wrong here. I REALLY am not against the rules per se. they are what they are, and if one wants to compete, then go with what is. What I am opposed to is the justification of rules by specious argument, such as exposed hammers being safer on the line (which I have heard). The real reason for the rule may have been to keep Ruger actions off the line in the spirit of the sport. Odd that the DeHaas-Miller actions qualify
Sorry I got this started, think it is time to just drop it, specially since it has nowt to do with fast twist!
Thanks for introducing me to the Shiloh forum. Learned something, anyway and I do have a little black feather hanging from the mouth...
Don