Building our own is always possible, but it's a limited use application. There would have to be some hefty sales projections to even consider the tooling cost. We're also trying to stay away from proprietary mags from a customer experience aspect. AICS can be found nearly anywhere if a replacement is needed, whereas if we went custom, you're limited on sourcing (and price).
The SRS/UM setup is freaking awesome, but as mentioned above, proprietary.
Most of the 223 AICS pattern mags can be modded to stretch out. As long as I can come up with a repeatable, efficient process, this may be the direction taken. I'm not opposed to modifying off the shelf mags to optimize usage in the rifle, as long as the off the shelf will function in a pinch. I.E. we mod them for extended COAL, but a standard works with reduced length.