We are assuming that the receiver work was done before WWI based on the patent date and that the receiver might be the original sample piece.(?)

The barrel and forearm have to be post war in order to have the later forearm metal. There is no standard serial number or barrel address to help date the parts. The barrel has the integral base used from around 1913 to 1926 on the featherweight barrel but this barrel has a larger diameter. My guess is that the barrel was special made to handle the larger bore (wall on a featherweight might have been too thin with the.35 caliber). I also think the barrel might be a proto. Why make a larger diameter barrel with an integral sight base vs. just putting a dovetailed sight on the front?

This is a very interesting rifle. I wonder if it sold with the other R&D rifles?

The barrel has interrupted threads which makes it an earlier one. Earlier than when I don't know. I know we've talked about when the change was but can't find it and can't remember it. I do know that an interrupted thread barrel will work on a newer receiver and that the forearm metal will also interchange. You'd have to slightly shorten the forearm tang to use the later metal though and thus lose any serial number that might have been stamped on the end. Curiouser and curiouser.

definate need to add this to my files

Well I received an envelop from Mr Callahan today and now I have a bunch more questions. I hope this pict turns out.

Very cool!