I just picked up a new M&P 15-22 at Sportsman's Warehouse this weekend for $395 and now looking at putting a Slide Fire kit on it which is another $395. Has anyone got any experience with a Slide Fire kit on this rifle? Is it worth the extra money? Any issues with it? Where is the best place to purchase, i.e. can they be found on sale anywhere? I've done a fair amount of research on these kits and have good understanding of how they work but just wondering if there is another type of manufacturer or solution of this type of full auto mod.