The 300 Blackout is a great cartridge and platform. The biggest problem with the 300 BLK is it is danged expensive to reload. The correct .308 (longer nose to ensure feeding) are pretty dang pricey and hard to find. If you aren't particularly flush (or semi-retired like me), you are loathe to do much plinking or practice like me. If I shop around, I can load 223 for 1/3 to 1/2 of what the 300 BLK costs. I ditched the 300 and built a nice little KISS carbine with a 1/7" twist 16" barrel. I can plink with cheap 55s, and load some 77 OTM bullets for serious thump.