Would jeweler's brass make an effective shield boss?

[Crispianus]

Hello,

I once again beg for your technical advice.  I've found a relatively cheap source of jeweler's brass, which I understand to be the same thing as red brass and jeweler's bronze, an 85:15 percent mix of copper and zinc.  It's supposed to look more like typical high-tin bronze than common yellow brass does.  So I was thinking of using it for one of those flat violin shield bosses and a domed boss for a center-gripped shield.  Is 14-gauge red brass likely to hold up to any degree of reenactment fighting, or is it too soft and/or thin?

Also, for anyone who's forged their own bosses, is it likely to lose a significant amount of diameter when shaped?  Is 6 inches too small to fit over a 5-inch hole?  If it makes any difference, I'm planning to affix them with a large number of escutcheon pins instead of a small number of rivets.

Any 14g brass should be fine for a boss but it will take damage all bosses do, how much depends on shape as well ie a conical boss is likely the deflect force better then a dome, of course if a dome is what was used then historically you have to stick with it.
With brass I would suggest successively annealing it as you work it and finally work harden it at the end or heat harden, most brass can be worked hot at dull orange quite easily in my experience.

My preference though for reenactment has always been a 14g mild steel cone, strongest takes least damage.

For the rim, work the metal outwards on the inside using a cross peen hammer to broaden the rim, its better fixing with a few nails rather then many small ones, though again use what was historically done.

Make the boss so your hand fits in it comfortably with a bit of space with it on the board, the short answer to shrinkage is no.

Generally I prefer to cut a shaped hand hole in the shield, rather then just a circle, with the grip as part of the shield board or grafted in, the upper part larger to accomodate the hand, and make the boss to fit comportably over this arrangement.