Of course you can't shoot it in PCC matches, but a 300 AAC Blackout using subsonic ammo is great for shooting AR500 targets at pistols distances. The subsonic ammo will not damage the targets in the least. You can also load subsonic 300 BO cheaper, with coated cast bullets, than you can buy 9mm plinking ammo. Just sayin.
I bought an MPX-P a few weeks ago for my 60th birthday. Sig had Individual Officer Pricing, which may or may not be available for future MPX's. The MPX is what I call my "old man gun". Wanted a PDW that was light recoiling and worked well with a red dot. The older you get the less recoil and more vision assist the better. I considered other manufacturers because I was reluctant to go with the MPX. While researching I was continually told get the MPX over Brands X, Y, and Z. Let me start this next statement with YMMV, but the MPX is the most fun I have had with a gun in a long time. I have much time shooting department UZI's and MP5's. This is a softer shooter. Magazines are about $50 each. Certainly not Glock price, but Lancer mags are solid. I'm open to ideas, need help justifying buying 10 round extensions because they cost almost as much as a new magazine. I have a bunch of 30 rounders and a few 10 rounders. 1500 rounds fired, zero malfunctions. My big complaint is the trigger. Geissele is working on one. They say their current triggers will probably fail within 2,000 rounds. Please let me know if there are proven options. Guess the only other complaint is how easy it is to shoot. A day at the range can get expensive real quick. Here are a few pics. Replaced the folding brace with SB Tactical's retractable brace and grip with Ergo grip.
Cool guns and gear guys, I'm jonesing for a 9mm AR now.