My FFL snagged a FDE Troy M7A1 Kit for me when I told him I wanted one of the North Eastern Arms Compact Carbine Stock. It was cheaper and upon playing with it, the Troy version seems better.
I only got a chance to briefly handle the NEA CSS. If you look at the picture below, you can see a button that looks like an AR magazine release. That is the button to release the stock. So it is not ambidextrous.
The NEA CSS also does not have that many stock positions.
Here is the Troy M7A1 Kit.
If you want the stock to collapse to the last stock position then you cannot run a BAD Lever. The stock bars will hit that too.
There is quite a bit of clearance between the stock bars and the sides of the lower receiver.
As I had noted earlier that the NEA CSS stock release button is not ambidextrous, the Troy M7A1 stock is. Not only is it ambidextrous, but you can open and collapse the stock while keeping your hand on fire control. Just reach back a little with your thumb and depress the stock catch.
The stock has six position stops and they are cut into both the left and right side bars.
The Troy M7A1 stock has QD sling holes on either side of the stock butt.
Due to the design of the integrated buffer and BCG the upper receiver cannot open in the traditional manner. The upper receiver will not hinge open because the buffer spring sits inside the upper and buffer tube. So you have to open both receive takedown pins and slide the upper receiver forward to remove it from the lower.
From L-R: Troy M7A1 BCG, PSA Full Auto BCG, Troy BCG.
The M7A1 BCG has some extra material, that I believe to be part of the buffer, that extends a little into the gap where the hammer hits the firing pin.
Below is the M7A1 fully extended vs the Troy Battle Axe Stock fully extended.
Now here are the two stocks fully collapsed.
When installing the M7A1 stock, you must remove the receiver end plate. The stock replaces the end plate and holds the takedown pin spring in place. So unfortunately you cannot use any end plate sling loops like the Magpul ASAP and have it on a single point sling.
Here both stocks are fully extended.
Now here are the stock fully collapsed. Both rifles have 16″ barrels and midlength gas systems.
One interesting note, the M7A1 stock bars are wider apart than the NEA stock. I installed the M7A1 stock on my Vector before installing it on my AR lower. It can fully collapse on the KRISS Vector.
Here is a video function testing the stock on my Vector and my AR.