Yep, 3x magnifier....both EoTech and Aimpoint make them.

Honestly...get some range time first, before leaping into that. I have found that I can easily shoot at 200 with my Aimpoint, and would be comfortable much further than that in a "SHTF" scenario. Would 3x help...possibly, but it's just more weight / added bulk.

Also...keep a close eye on Vortex products. Their customer service is really getting alot of buzz, and they came out with a 3x magnifier also....in case you want to "try" the concept at a much reduced rate.

If you go scope, or any other optic / accessory, take a look at Larue Tactical...they have mounts for everything. Expensive, but the best. Given your taste in knives...I suspect having the "best" is of interest to you.