What is the difference between the Action Kit 6760 and 6832? What does the extra $50 get you?
Besides being 50.00 more it says (Pro/ Mil spec ) ?
One made in China,the other made in usa
How many shots pr fill?
When tested it gets up to 3 magazines worth of useful shots. You can see a video of it being tested on the marauder pistol on that pistol page.
What's the difference between a Pro/mil-spec and a basic AR15-style shoulder stock?
I do not believe that there is a Pro/mil spec designation. There is Mil-spec, diameter 1.148" and Commercial at 1.168". If this is Mil-spec, then it will accept any Mil-spec AR15/M4 aftermarket stock.
The diameter of the extension tube is different. It does not change the basic function either way.