Thanks. My Red Dot search continues. As far as Springfield I agree with the phone call to customer service. They have responded quickly and efficiently in the past. I just felt an email would be easier. Guess not. I do not think after having 4 of their pistols I am likely to try a fifth. I've owned Glocks, Smith and Wessons, Sigs and a few others. 9s, 40s 45s and a 380 mostly. Toss inn occasional 25 38 and 357s. All have been fine guns. The Springfield in either 9 or 45 just fit better in my hand (grip angle, etc). The magazine problem, at least for me, was just getting rid of the flared part of the mag well. The old mags work no problem. I just did like the baseplate of the new mags. Oh well.
Am not thinking SA sells just mag base-plates to consumers as in like to the members here. Complete mags, yes. From looking at SA's WEB store, that's what's available. There are some other online aftermarket companies that do sell the base-plates if you do a web search. Some of the aftermarket base-plates also offer extensions to increase mag ammo.
SA's Store: https://store.springfield-armory.com/Shop/pc/Firearm-Accessories-c13.htm