A few months ago I bought a Shiloh Sharps Model 1874 chambered in 40-65.  The rifle was built in the mid '90s but is flat new.  Without having to do a chamber cast or slugging the bore, does anyone with one of these fine rifles know what the groove diameter is?
A friend gave me two boxes of Snover .40 SPG ... They are measuring .409 -.410 and I found the bullet weight on line at 410grs.  Will this work?
Any and all help is appreciated.
Thank you ...
Joe D

  Another issue you might want to aware of is that Shiloh and Ballard Rifle and Cartridge use a different chamber design on their 40-65. RCBS makes a set of dies specifically labeled "Shiloh and Ballard" I ran into this issue several years back and had to return a set of dies and procure the correct ones before I could load ammo for my rifle. Things may have changed, anyone else please chime in if they know any additional input on this particular issue.

SSS

Joe, from what I have seen on the Shiloh board is the bore should be .400, with a grove of .408. I am not sure of the twist but you can check that on your own with a cleaning rod and tight patch. 
One problem I ran into with my 40-65 was the chamber was cut with a small base reamer. Mind is on a Browning 78 action. I couldn't quite chamber cases run through a standard CH die, but I did manage to pick up someplace  a FL die that someone had shortened and once I ran the cases through that die they chambered just fine. Once they are sized with the shortened die I didn't need to use it again, just use the Standard FL die to reload and all worked well. 
Your Shiloh should be a very good shooter with that Snover bullet. If this is your first venture into the world of shooting black, a case full of powder, a little compression, an over powder wad, and then I like to add a wax paper wad, then your bullet. The wax paper will prevent your over powder wad from sticking to the bullet and the wax paper will easily fall off with no effect on the bullet. 
If it should happen that you would need to run your cases through my shortened die, let me know and you can borrow it for the price of mailing it to you. 
Sam

Thank you All for your help.

Clarence - what bullet and load do you shoot in your rifle?

Shoot 56 grains of KIK 2f with the Saeco 740 and 57 grains of the same powder with the Saeco 640.
Tested extensively by Bill Bagwell (rdnck)

Wiping between shots is no sweat. You'll establish a rhythm and will hardly notice that you are doing it. Get a tuper-ware container for your patches and wet with your favorite elixir and you're ready to go. I use the Arsenal patches and a stiff brush on the rod and use a 20:1 mix of water:water-soluble cutting oil and works well.

Also have the 400gr 'Money' bullet, as well as the 450gr. My 40-65 should be back from John Taylor next week and will see how 58gr of 1 1/2F Swiss works, to start with. With Shippensburg this next weekend and the Eastern Regional 2-day match the next and then our 600yd mid-range match, won't get much time to develop a new load for a new rifle. Winter and next season.

Clarence,  one thing I've found is that you can save a pile of time by separating your patches before a relay.  ( Keep the lid on the patches between relays to prevent them from drying out in the hot sun. ) I noticed that often I'd waste a lot of time separating patches from each other.  Now my routine is faster than blow tubing.

Chris.