Im looking at getting a bipod for my Olympic Arms AR. My biggest concern is the length, should i get the 6-9 or the 9-13? I have several 30 round mags but no smaller ones, so I am afraid that the 6-9 won't be high enough for the 30 round mags. Mainly bench shooting and some prone.
id throw a 30 rd mag in and set up like your gonna be in a bench maybe on your kitched table and have someone else measure from the table to the handguard. add 2-3 inches for wiggle room and your good to go.
Have had a 6-9 for several years....use 30 mags without any problems. Best bet would be to find a friend or friends who have both sizes and give them a try. The larger size might be what works for you.