Everything I've found so far lists it at Roberts Improved, the original label in his writing says so, he wasn't one to make mistakes of that nature, and the dies I bought are also matching that.
Figure it out eventually. Is there an easy way to measure the angle of the chamber?
This is the tag that was attached to the gin when I got it, everything matches with the stamping of G33/40 on the receiver.
![]()
There are actually 5 or 6 versions of Improved Roberts... you should do a chamber cast and send the specs to Dave Kiff at PTG... he can match the specs to a die and/or send a blueprint to a custom die shop... the custom dies will set you back close to $300 though.
A few custom gun builders back in the day had their own specific reamers made up with their own provided dimensions, I have that came out of a shop in Seattle, fortunately the differences are so minute that I can use the 257 AI dies without issue.


















































