The nipples should come out with little troule. I've found that the Universal nipple wrench from the Possible Shop is the best all round wrench you can buy. It's a little pricey; but you will never break it, even on the toughest most corroded nipple.
Colt Universal Nipple wrench is made from carbon steel and has nipple slots of about .196” - .236” and .275”, and screwdriver tip. Combination wrench fits 1851, 1860 and 1858 Cap & Ball Pistol - AMPCO, traditions and Musket Nipples. By Pedesoli.
Description Order No. Price
Universal Nipple Wrench 45-016 $26.95
I've got two of these, the oldest being about 20 years old, one in my shooting box and one on my workbench. At one time or another, I've bent broken or stripped out all the other nipple wrenches you can buy. Even the vaunted Ted Cash ratcheting wrench.
Fingers (Show Me MO smoke) McGee - AKA Man of Many Colts - Alter ego of Diabolical Ken; SASS Regulator 28564-L-TG; Rangemaster and stage writer extraordinaire; Frontiersman, Pistoleer, NRA Endowment Life, NMLRA, SAF, CCRKBA, STORM 327, SV115; Charter member, Central Ozarks Western Shooters
Cynic: A blackguard whose faulty vision see things as they are, not as they should be. Ambrose Bierce