I also have an slr 101-13. I picked mine up 2 weeks before the election. The writing was basically on the wall with that one.
Anyway, yeah tapco mags suck. Do NOT buy waffled tapco mags. They will not fit your rifle. The non waffled will fit eventually... after loosening up a bit. Still I recommend Bulgarian mags. They are machined for your rifle and will fit in their with a nice click just like the 5 rounder your rifle comes with. I know they are a bit pricy but I'd rather have 2 quality mags then 5 crappy ones.
+1million on the Arsenals are bad @ss guns but the finish sucks walrus testies. I love mine. The thing is a tack driver man, with irons at 100 yds. When I mount an aimpoint red dot I expect nearly the same accuracy at 200.