You are exactly right in your observations. It seemed odd to me, but that is what they did.
I'm ready to give it a try. I think the Rock River TDP is the one to go with. The extra length will help getting the pin to move like you suggested. The larger diameter pivot pin might just fit. The DPM pins I bought are just a little too big in diameter so I'm hoping the one you have will go in without galling. I'll make the holes bigger if need be.
Do you have any need for these DPM pins I bought? I'd certainly be happy to send them along. In any event, what do you want for your pins? I really appreciate your help. This is a great site. I'm sort of itching to build an AR-10 from scratch and now I know where to go to get any information I might need. I will PM you my contact information. Please let me know if there is anything else you need from me.
Thanks everyone,
Gary