New member here. I do not own a Keltec and have not actually even held one but have considered them in the past. I recently saw a video of the Series M (MCarbo) sub 2000 which includes trigger upgrades, sight updgrades, charging handle upgrade, etc. It seems like they have replaced a lot of the plastic parts with metal ones with this series and it keeps the warranty of Keltec and M carbo. Does anyone own this series and if so how much does it increase the quality of the weapon? I would be using it as a back up defense gun and also to shoot steel targets with. Even though it would be a backup weapon for me, I dont want to spend money on any weapon I dont trust. Other 9mm rifles I am considering are the Beretta CX4 (almost impossible to find) and the CZ Scorpion (getting more expensive by the day). How close to dependability and reliability would you place the upgraded Sub 2000 in comparison to these? I have also considered the AR9 platform but everything I read seems to indicate that they are very finicky unless you spend big money on really top of the line stuff. Thanks very much for your help.