Here are a few details of my CCU mods:
Normally an extended saftey doesn't work, but I used a wide lever and took enough off the INSIDE edge that it will bypass the outer edge of the receiver tube. There is also an extended mag release and mag well on the frame.
I added the Mechtech sight rail, but retapped the hole for the front sight and replaced it with a tritium AR15 sight(XS 24/7 model). Before the sight/equipment rail had been added, I had put the rail on bottom for a light. When I moved the light I added the vertical grip to the bottom rail. A pair of Surefire 6P's cover tac lighting. The BSA dot has been very reliable through a few thousand rounds.
Mechtech had promised a telescoping stock, but it never materialized because of the AWB. After the AWB expired I contacted them to see if they might offer one in the future, but didn't get an encouraging response. So I took matters into my own hands and I made an adapter at work for the M4 stock.
I use Wilson Bureaucrat and Ed Brown 10-rounders exclusively. They are the most reliable I've found. And I haven't found any over 10 rounds that are reliable enough. This is the weapon I usually grab if something goes bump in the night.
Best accuracy comes from +p HP's. Both the Corbon 165 and the Black Hills 230 shoot into under 2" at 50 yds. Standard 230 grn ball shoots about 3.5" at this distance. Mine is heavy, but recoil is about like a .22 mag.
I thought the distinctive "twang" you hear is from the stock, but it still does it with some the M4 stock. I think it is from the recoil spring more than the stock vibrating like a tuning fork.
When I bought mine, 1911 was the only flavor available. Otherwise, I might have gone with the Glock package. On the other hand, it is easier(and if you shop around, cheaper) to set up a separate frame for the 1911 package than to get a Glock frame. Thought of changing to a Para-ordnance frame for increased capacity, but haven't decided yet. I like having mag interchangebility with my other 1911's.
The only reliability problems I've encountered was with a friends' match pistol. The frame needs a little looseness (or "wiggle") it seems when pinned into the CCU, and his was so thight it wouldn't even reliably feed ball. However, his was very reliable when attached to its own slide.
This is perfectly legal and there's no real way to easily screw up on this matter
Unless you try to cut the barrel off in front of the handguard. Then it would have to be SBR registered.
I'm sorry for you guys in Kali. You miss out on a lot of fun toys.