The MP 443 is, in my opinion, the most reliable and reasonably priced secondary in the game. Why wouldn't you just buy the .45 with the more powerful shots? Because it's only 2 damage difference and with the MP443 you get more than double the shots. It's also somewhat affordable. You can buy it for under $5 in game cash unlike the MP412 REX.
Whoever has something better than what I put can erase what I put, but don't grief this page(I like the MP443