The required load for the Uberti .36 cal. 1851 Navy Revolver is 18 gr of FFFg black powder; a .36 cal revolver wad; a .376 round ball; and a #11 size percussion cap.
The #11 size percussion caps fit loosly on both Pietta, and Uberti revolvers, that's why they need a little pinch between the fingers and thumb so they'll snug up against the tapered wall of the nipple.
To save you time and money on experimenting with the various brands of caps. The Remington #10 percussion caps fit better than any, and have plenty of ignition to prevent FTF's.
The most important issue with the Remingtion's is that they have a longer cup to seat down on the snow-cone shaped nipples. Therefore a little effort is needed to insure they are seated flat against the end of the nipples.
Black Powder revolvers are mild shooting handguns. I have the 1860 Army .44 cals, and they don't kick at all. Now the .44 calibers in a Walker style stuffed to the gills w/bp might buck some, but you're mostly wasting powder .