Hornady Flex Tip Ammo requires a "special" seating die that I believe is only available from Hornady. But as stated, that die can be put into any press that takes the 7/8"-14 size dies. If you purchase a Hornady die set maybe you can get it with the "special" die and save yourself a few bucks.
No special die need for seating. I use the same Hornady die for FTX 325 as I use for 525 gr Piledrivers. Lee FCD even works on the shortened cases.
@Skinnersblade - FTX are fun to shoot, and work great for deer, boar, and presumably black bear.
I'm reloading close to 1000 rds per year of 45-70. I used to shoot nothing but FTX, but a couple years ago, I switched to lead alloys. The 405 gr bullets I shoot come in lots of 200, cost about 28 cents US per bullet (including shipping costs). My total cost per firing with those is about 41 cents (10 reloads per brass).
I repeat the same advice to everybody new to reloading. It is always tempting for new guys to try and squeeze out every last foot per second of velocity possible. With 45-70 and lead or lead-alloy bullets, this just isn't necessary. Remember, during the heyday of American bison hunting in the US west, they were shooting 405 gr soft lead or paper-patched lead at MV of 1250-1300 fps, and killing bison at 500+ yards. A wide meplat, heavy bullet moving at 1500 fps will punch a hole clear through anything you'll ever hunt in North America. I push mine (405 gr, 425 gr, and 525 gr) a little harder than necessary - about 1625 fps - but that's still well south of max for those loads.
My 45-70 wouldn't be my first choice for coastal browns, but if I were hunting moose in coastal brown territory, I wouldn't think twice about using my 45-70 for moose, and as a CIWS for nosy bears.