Jamison brass rim

[Nuclearcricket]

Ken, if everything else on the case fits the way you want it, it would just be easier to have the case rim cut to fit the diameter that you need.
My question to you is, are your sure the numbers you put in your post are correct?
To reduce a rim diameter by .150 is a lot, a way lot. My guess is that the Jamison is .550" and needs to go to .500.
How many cases do you have on hand that would need to be reduced in diameter?
I have a small lathe and am a retired toolmaker and could easily do the work for you a the cost would be minimal, I am thinking somewhere around .25 a case depending on how many you have, plus return postage, providing your here in the US.
Sam