For BFA size see the chart below and size in the checkout comments. If no size is given, you will be shipped .125.
20 inch barrel .120 BFA recommended
We have thoroughly tested for positive function in modern 30 round magazines with anti-tilt followers as well as Surefire 100 round coffin mags.
Most 20 round magazines will not feed well with this round though PMag 10 round mags work well for those in States with mag limits.
16 inch barrel .125 BFA recommended
14.5 inch Barrel .130 BFA Recommended
10.5 - 11.5 inch barrel - .135 BFA Recommended