For your M1867 Spencer, you should use .512 diameter bullets. These are suitable for the barrel and will work well with your reloading setup. You can find these bullets from suppliers like Hornady or Moyer's Cast Bullets.

Cool here today, got called in to work, boss' kid was sick. So off tomorrow. Supposed to be sunny and cool again tomorrow. Y'all be good.

Here consider the RCBS 44-200-FN or the 44-200-CM.

I choose the FN as my first 44-40 crimp-able bullet but not historically correct shape.  Then went to the Lyman 427098.  Then final bought an Original Winchester 44WCF mold.  Stuck with BP and the original for many years.
 

https://www.rcbs.com/bullet-casting/moulds/bullet-mould-.44-200-fn-595/355308.html


https://www.rcbs.com/bullet-casting/moulds/bullet-mould-.44-200-cm-636/355306.html

Gonna have to check them out. Thanks!

Quote from: Little Dalton on Yesterday at 07:17:00 PMif a big lube groove bullet is needed, the Accurate 43-215C designed by the late John Kort is more accurate at longer distances. It has a single big lube groove and will carry enough lube to deal with dirty powders like Goex, Scheutzen, etc

This is the bullet that I use. When it's loaded, the exposed part of the bullet looks very much like an original.

Had a dusting of S**W here today,just a prelude of things to come.  

It's a decent choice for CAS distances, but if a big lube groove bullet is needed, the Accurate 43-215C designed by the late John Kort is more accurate at longer distances. It has a single big lube groove and will carry enough lube to deal with dirty powders like Goex, Scheutzen, etc

Quote from: Lucky R. K. on Yesterday at 09:53:59 AM
This is very good reasonable advice. A good choice for a bullet, if you can find the mold, is Dick Dastardly's Big Lube Mav Dutchman. It is about 200 grains in 44-40 and has a lube groove that will carry enough lube for the longest barreled rifle.

Lucky   

Rugers
 -2 separate consecutive sets of Ruger New Vaquero Montados .45 3 3/4" stainless, manufactured in 2024, Ultimate Short Stoke by Classic Single Action. NIB+short stroke. $3500 per set of 2 consecutive guns

   BIG   PLUS   ONE for CROW CHOKER   

Just for reference, here is a bullet cast from my original Winchester mold.  The reduced picture quality required to post reduces the detail, but this should give you an idea of what the Winchester molds produced.

Griff