WOW! I had forgotten about this thread. I have since bought a Uberti 1873 carbine in .44 Magnum too. Hands down, it is the slickest out of the box action I've ever operated. I've owned it for over a year and still get wobble-kneed when I see her in the laundry room gun rack! OK, now for your issue....
I'm afraid the SAAMI o.a.l. for the .44 Magnum is 1.610" and the 1873 rifles, even the old ones, have carrier blocks that are 1.610" in length. So, the o.a.l. of any cartridge in the '73's is limited to the length of the carrier. With my NOE 429421 mould this would require seating the bullet just to the front edge of the driving band.
So this problem requires some creative thinking. The quick solution would be to trim about .085" from your .44 Magnum brass, crimp in the bullets crimp groove, and be done with it. Another option would be to seat the 429421 to the correct o.a.l. then apply a crimp with a Lee crimp die. The only other thing I can think of, and it doesn't sound like a viable option for you, is to have Tom at
www.accuratemolds.com make a custom mould for you that would cast a bullet that would result in the o.a.l. you seek. He doesn't charge any extra for custom designs, by the way.
I haven't fired any .44 Magnums through my Uberti as I really bought it to use with my .44 Specials as I typically load them a hair over book loads all the way up the Keith load that I fire in my Flat Top Blackhawk. I haven't done lots of load development yet, as the rifle so far has been a companion in the deer blind when I'm handgun hunting. Nevertheless, it's been pretty accurate with .44 Special loads, what little I've fired it.
Please keep us posted with your decision and results and I'd love to see a picture of your rifle.
35W