I'm a Gunner, Have a few boom sticks and try to be proficient with them. Mostly Sigs and Smith so the Manual of Arms is pretty stock. Long Guns run to AR's, Mauser Bolt Guns and Remmie or Benelli Shotties. Here's the thing, We all talk about what we would reach for a given day but have you ever validated that choice? Nothing like a Brookings Institute White Paper but actually shot your choice of weapon.
Shot an IDPA Three gun match for grins and giggles but found out some stuff. Magpul P Mag doesn't like to seat with a full mag and a closed Bolt. OK, Need a little adaption there. Location of Magazines on person and WHAT type of pouches are you using. Some aren't worth the nylon and Velcro they are made of. Shoot a Match Sometime with your SHTF Stuff, See if it does what you thought it would do. Don't worry about Times, Score or Points down. SEE if your stuff works. There are Gamers out there that have all the gimmicks, don't fall into that hole. Keep it simple, Think out your kit and build it accordingly. Then Test it. Proof of Concept. Good Luck.