Does DSA make these or does someone else and are they a good buy?
I was under the impression that they are using POF’s piston design. 
My reply is not meant to start yet another POF bashing thread or debate DI v. piston.
IMHO this is not a bad thing…
There are many that have a gripe with POF, some for good reasons. I am not one, I have an 18" SPR and love it.
As far as piston systems go, I personally believe POF is a very good design. Most POF gripes are around the fact that it is a proprietary design and that sometimes their Customer Service is lacking. Both fair points, but you will not find a “standard” piston system in the world (no such thing), I like their spring free approach and in the unlikely event you’ll need customer service you’ll likely be treated well & fairly. I had a bad early Timney trigger and Chris & Frank were great to me.
Buying from DSA is prolly a good thing as they’ve been re-selling POF uppers on their lowers for 3-4 years. NOTE: their version ships with a DSA lower (not the billet POF lower). Pricing is (was) very close to POF direct. Bushmaster also sells the POF design.
Good luck…
They use the POF system.
C4
I’ve never thought they were a good buy at $1800.00.
They are just a POF upper on DSA’s complete lower and when you look at that you can get the same upper from POF for $1250.00 or less from an outside dealer, than get yourself any lower you’d like to put it on and do it for cheaper with more choices.
That’s the way I did it and came out at about $1500.00 total for the upper on a Mega lower/Stag parts kit.