Deleted, my post adds no new information.

[Earl Brasse]

Deleted, my post adds no new information.

[Black River Smith]

I hope this helps you in this early phase of learning.  The Cimarron rifles are not designed to the Winchester specs.  Period End.  I suggest you read a lot more before starting to buy and cut and size any brass.

I make this statement when I do not have a Cimarron rifle but a Chaparral which was design to be 'about' the same as a Winchester.  Also, I have the 45/60 not a 45/75, but I have read most of the posting in this forum.  I read peoples issues with the brass alterations for both cartridges.  I also tried to reach the Winchester 0.629 rim diameter for my rifle.  From experience don't bother to try that.

The statement that seems to apply the most for Cimarrons are the bolt face/size was made to 'more easily' correspond to the rim dimensions of the 45/70 casing.  One last thing that I know from the postings, Cimarron had two different Chamber cuttings for the 45/75 shoulder.  You will have to figure out what one your rifle has.  Sorry, I do not know the details/dimensions of these two different chamber that where used, or the manufacturing timeframe for each.

If you read through the many pages of posting you will see all the trials and errors of the many posters.  You will eventually find the answers that you need; the techniques to get to; and maybe even the correct dies to buy, in order to get a Cimarron usable cartridge.

READ A LOT MORE IN HERE.  My best advise.

[Earl Brasse]

Yes, thank you for your insight, deleting post as it offers no new information.