I must be doing something wrong, I can't seem to find a solution for using my M&P 15 Sport with a bipod.

I ordered a Harris #2 adapter from Amazon since some of the reviews indicated it would work with the sport - it does not.

I ordered a quad rail from Amazon that according to several reviews was a drop-in replacement for the M&P 15 Sport - the product I received did not fit the sport.

What are some options that do work with the M&P 15 sport? I want to either use a Harris style bipod that I already have (swivel stud) or get a rail that fits and buy another bipod with a weaver mount. Help please.