It’s possible for there to be a small nipple sticking out of a musket ball, but that would indicate it hasn’t been used. The projection would be the remnant of the “sprue” where the molten lead was poured into the mould. That would be cut off with a pair of snips before use. Shot that was put inside a shell to act as shrapnel (grape shot or canister shot) might not be trimmed off with the same degree of care and could be iron or lead (and occasionally brass). If it were iron, it would be magnetic, even if heavily corroded.
Musket Shot would always be lead and non-magnetic and nothing like as large as an inch across. Also, if it has been in the ground a while it tends to have a greyish or white oxidised powdery coating. Like this one, which is English Civil War period:
Jude’s item looks like an ironstone concretion to me. Those can be perfectly spherical or have one or more knobbly bits sticking out of them, and the colour and appearance will depend greatly on how they have weathered. Like these:
Also, from the measurements, I estimate the density as approximately 4.4g/cc which is far too low for lead (or even iron) and much more consistent with rock/mineral.
Ironstone concretions are rarely magnetic and if so, normally only weakly. Time for a streak test (on the unglazed side of an old ceramic tile). Hematite streaks red-brown, limonite and goethite streak yellow-brown, pyrite streaks black (or greenish black). Magnetite streaks black or grey and is strongly magnetic but not normally present in round concretions except as an accessory mineral at low levels. Lead would have an unmistakable grey metallic streak… but I’m sure it’s not lead.
Lissa’s item looks much more like a piece of shot, but it doesn't look as if it has spent much time in burial and (although it's the right kind of size) might still be canister shot rather than a musket ball. Try a magnet and a streak test on that one too. It’s not difficult to calculate the density accurately if you have access to a decent balance and a pair of calipers. That will at least tell you for sure what metal (or alloy) it might be.
Edited by painshill, 12 April 2013 - 12:33 PM.