Careful with the Harbor Freight T-handle hex wrenches too - they round off easily with too much force. My brother ruined a set I got him working on his little RC nitro trucks in no time. They're not exactly the most durably-made Chinese metal tools you can get.
I have a Harbor Freight credit card, so I get free reward gift certificates and buy the Chinese tools all the time.
As mvician stated, the stock won't be a killer to install, assuming you have a stock wrench. The
RRA wrench works great on M4 6-position stocks with the 4 equally-spaced notches in the castle nut (the wrench pokes into three of the four notches for a more positive grip), but it won't work at all on CAR stocks with holes in the middle of the nut like my Bushmaster CAR stock has. For CAR stocks or M4 stocks that may have a nut with no notches around the edge, you'll need the
old style wrench.
RRA
is well-known for using Loctite on the castle/lock nut, so you may need to really work at it and/or heat it up with a hairdrier/heat gun to get it to turn.