Re: SR-25 Magazines
I have used all of the following KAC-pattern mags in addition to the KAC factory mags which just plain aren't worth the ridiculous prices that KAC and retailers are demanding:
1) Magpul LR-20 PMAGS;
2) DPMS LR-308 Mags (4, 10 and 19 round models); and
3) C-Products (5, 10 and 20 round models).
The new PMAGS are THE mags to get. They are 110% reliable out of all the rifles I have used them on, they will hold a true 20 rounds in the mag with a round chambered giving you 20+1 capacity, the PMAGS will allow 175gr Match length factory ammo to load and feed from the mag (and you can actually go a little longer with reloads), and you CANNOT beat the price at approx. $20/mag delivered.
Mark Larue is also in the process of manufacturing a KAC/DPMS compatible 20-round mag for use with the OBR. I haven't been keeping up with the progress on the intro of these mags, but they should be available soon if they aren't yet out. These should also prove to be excellent mags.