I was at the local gun store yesterday with this exact same issue. They are usually very helpful, but had no solution on hand for bipodding my M&P 15 Sport.

My California compliant model has standard round rails, a sling swivel on the front, and a bayonet lug, if that makes any difference. It might be better to avoid attaching metal to metal due to heat issues, I would think.

So if I get a #5 adapter, I can use the Harris bipod. Okay.

But which Harris bipod? They have more than one. I don't want to go the online order route and then have to do an exchange.

Any advice, please?