On the 18 rd mags is there any way to change it to 15 rd with an adapter or or different plate on the botom of the mag?
You just need to replace the mag extension on the 18 round mag with a standard Echelon base plate and you will have a 15 rounder.
Yes change to the 15 rd shorter spring and 15 rd baseplate from Springfield and your good to go
I don't believe so either.
I don't believe so.