Butch, are you open to a few suggestions or are the parts already ordered?
Sure!
16" at the max length. Even those are hard to handle getting in and out of a car. The lighter the profile the better. It'll be carried a LOT more than it's shot and if it's heavy it just won't get carried or trained with like it should. Mid-gas for a 16" barrel, but that's probably all that's available.
I'd opt for a gas block that's either pinned, or at least dimpled. We've seen those exposed clamp on gas blocks come loose. I'm not sure I've ever seen one survive a rifle school, but can't say for sure. Dimpled / pinned and covered with a rail is a much safer bet. Gas blocks are a major failure point.
I'd go a bit longer on the rail. Looks like WOA offers that rail in 14.6". It'll allow him to mount a light further forward to minimize shadowing and make shooting off a barricade a little easier.
The UBR stock is heavy. Again, I'd try to keep it as light as possible.
And have him check to see if his department has any special restrictions. That Tricon trigger may be too light (we have a 4# minimum). And just random restrictions that some cop working at a range thinks make sense. For a long time we couldn't carry anything that wasn't factory assembled. Well-intentioned family members would buy really good rifles that couldn't be used.
