Has anybody else experienced this? I played a game of regicide with the storm rifle, plasma pistol, and pulse grenades, because I had no plasma pistol kills and heard that was a good way to do it. I got 5 in the game, checked the commendations, and still had 0 listed. Next game I got 3 more with the pp, checked, and it counted those 3. Why the heck didn’t it count the first 5?!? Video is in my file share if anybody is interested. That’s a pretty glaring mistake if you ask me though (hence my posting about it).
I don’t honestly pay that close of attention. All I know is that I do have kills with the plasma pistol, and they are very difficult to get. Usually I get them by complete accident. Such as when I want to rip someone’s shield off and a teammate happens to pop their shields first… then BAM. I don’t care nearly enough about commendations and poses to agonize over attempting to get them deliberately.
I believe the Plasma Pistol is one of the hardest, if not the hardest, weapon to master. However, it does give some pretty cool kills if luck is on your side. I EMP’d a Banshee on Ragnarok once and it landed in the face of its teammate as they shot an Incineration Cannon. Causes a suicide and a Plasma Pistol kill in my team’s favor 
Plasma pistol isn’t difficult to master, per se, it’s simply that the weapon is not designed for direct kills. It’s kind of absurd that the commendation for a weapon not designed for direct kills is based on kills. Makes sense to me if they would include EMPing as a point as well.
At least that one isn’t as bad as the “kill mongooses” one. Dear gods, my second favorite helmet in the game is the air assault one, and I can rest assured that I will never, ever, be able to obtain it because of that one commendation requirement for vehicle mastery. It should be removed from the list entirely unless they introduce a race game variant that uses rockets and mongooses. Bloody impossible to get. I play a ton of BTB, and I haven’t earned even the first rank of it.