I can't say anything good or bad about the NWMP carbine either for Chapparal or Uberti as my rifle is a very early Uberti with the larger chamber. As I understand it now the chambers are all emulations of the original ones. As far as bullets are concerned, until I got my Hoch custom mold, I had quite good luck with Buff Arms 350 grain bullet. Now what i am using in conjunction with my custom mold are bullets that I cast using an alloy of 16:1 which is what the originals used. I make my own alloy. As far as powder is concerned, In using BP, I really like Swiss 1½ as do others that I have talked to. It burns cleaner than the other brands.
As far as the stock work is concerned, I did scrape off the original finish without sanding the wood and then hand-rubbed an oil finish that turned out quite well. I also stained the wood prior to the final finish to darken the wood and bring out the grain better.
As far as dies are concerned, I am using Lee dies that include a Factory crimp die along with a special order Trim and File die from RCBS. If you were to check with other places like Redding or Hornady you may be lucky and get a T&F die cheaper from one of them.
As far as brass is concerned, I have used Bertram(stay way from that as it is too $$$), I have used 348 brass which is tough and great once it is prepared, and Starline 50-90 brass which is good also but the best is Jamison brass. It comes all ready to go and is even head-stamped with "45-75WCF" on the case head.
As far as the rifle itself is concerned, I had a verry bad experience with the Chappy people and got a Uberti instead which, as far as I am concerned, is IT!
Hope these comments have been of some small help for you.