Ten-X is a good outfit and I worked with them when they were developing their ammo.

For some reason they could not believe/could not be convinced that the Martini Henry with it's long tapered .468 diameter throat and .464 bore needed or could be shot with the larger bullets and made their bullets .462. These bullets are undersized. I don't know what you call respectable, but I have to yet see 50 yard group with undersized bullets in a Martini that I would call respectable.

Slug your bore by driving a soft .50 caliber round lead down the bore from the muzzle. As you are pushing the slug down the bore pay particular attention to the feel as you approach the chamber if the slug loosens up you most likely have a tapered bore.

To measure the slug close the jaws of your dial calipars around the slug, leave the sliding jaw loose and roll the slug between the jaws while keeping a very light thumb pressure on the sliding jaw. The jaws will open and close as you roll the slug. Watch the reading on the dial and note the high reading that repeats, this is your major diameter.

Some commercial 577/450 Martini bores will read .458 to .460, but most are larger in the range of .464.

If you felt a tapered bore then the throat will be .004 larger than the bore or .468.

If you go to www.martinforum.org you will find a lot of good information on loading the Martini. The board is getting ready to do a group buy of Jim Goodwin great .468 480 grain bullet mould. The mould will be made by Jim Allison at CBE. After the group buy the mould will be standard inventory with CBE. The group buy will start taking orders soon with delivery in September.