I decided to build a new AR-15 in 9MM that uses Glock magazines using the Law Tactical folding stock adapter and one of the Dolos kits, to make a take down, compact 9MM PCC.
For the most part the build is working out. That said, I've run into a few issues with some of these special parts. The folding adapter uses a machined part they call an extension. This part is designed to be plugged into the rear of a normal AR bolt carrier group to make up the difference created by the adapter. The issue is that most of the 9MM BCG's are solid to add weight. This means that you have to modify a bolt to make the extension work.
I haven't completed the build yet as I'm waiting to choose the handguard, barrel and figure out which way I want to go with the bolt. JP Enterprises makes a 9MM bolt that is also hollow but it's $250.
Another part was the Odin Works pistol buffer tube. They use a proprietary end plate that has loops for a sling. It's designed so that you can use a stabilizing brace and use their clamp to adjust length. The tube doesn't have enough threading to use a normal castle nut. Because of the loops on the plate you cannot fully fold the adapter as one of the loops gets in the way. While not really a big issue, it's just another specialty part that isn't fully compatible with the rest of the specialty parts.
The upper receiver is one of the side charging, last round bolt-hold-open from New Frontier Armory. It's a billet receiver that's well made. However, there's a chance that the Dolos adapter won't work with it as the website reports it doesn't work with "many billet receivers." I haven't purchased the Dolos adapter due to cost.
I'll post on how the build went what I had to do to fix the issue.