Rifleman1776: No problem; no hard feelings. Was just clarifying.
GZRob: I'm not sure I completely understand the question. It is as comfortable as can be expected when in "lobbing position." The stock shape is the same as the piece it was patterned from.
Cynthialee: Ha. No live grenades, but Tennis balls are pretty fun. One can also use hollow steel balls. These are available from several outfits that sell architectural metalwork.
Hollow Balls
They are pretty lightweight, but heftier than a Tennis ball. I have always thought it would be neat to see a ball-shell fired from one (by someone with professional fireworks experience and the proper licensing, of course):
Ball Shell
As for specs for original grenades, DeWitt Bailey discusses the Musket-Mortars and their ammo in his book, "Small Arms of the British Forces in America 1664-1815" (pgs 209-210). I suspect that the specs would be much the same:
Shells:
Exterior Diameter: 2.42 inches.
Interior Diameter: 1.701 inches, 1/64the of the shell: 0.037 inches.
Thickness of iron at top: 0.302 inches, 0.415 inches at the bottom.
Dimensions of the Fuze Hole at top: 0.500 inches, 0.463 at bottom.
Weight of Iron in Shell: 1 lb., .03 ozs.
"The quantity of powder to fill shells is found thus: the Interior diameter being given, first find the number of cubicle Inches in the cavity by cubing the interior diameter [1.701] and multiplying it by 11 and dividing the product by 21 which will be the cubical inches in the cavity. Then divide them by the number of cubical inches in a pound of ordnance powder and the quotient will be the pounds of powder to fill the shell."