Aye some regiments do lack discipline and tolerance of some young guns can only be tested so much, myself I'm 17 a Army Reservist and at college, However the majority of staff in the 87th have cleard the 20+ mark, A Kentucky National Guard Master Sergeant, a Graphics designer from Ohio, Retired Farmer from Ireland, Uni Students, and so on. We give out promotions on how some one acts outside of game and how they can uphold themselves as a soldier, cause lets not forget this a war game! Regiments which throw sergeants to 13 year olds because they can spin and kill 50 people in melle can do it that way if they like but personally I hate that way, I want an NCO who can take charge of a situation and control the men. Something which I want the Privates and Regulars who are 15 or 16 to look up to and think "Hey that Bombardier P Smith is a cool guy and a good leader" Who takes notice of an officer or NCO who just shouts in your face and swears all the time, normally no one. Officers and NCOs don't need to shout either, a taking aside, a stern voice and a "Sort your act out or get out" normally gets the message across.
We have a 15+ Age limit but trust us, we make sure we weed out the annoying children who lack discipline and a mature manner in the recruit phase, however it is also game time and cool down time so not every one will be dead serious in games, some regiments are better than others and you will have to look around to find your best place. Some regiments are solely based on NW while others play a selection of games to occupy there time when not killing the French. Hell We got ARMA, Minecraft and Crusader Kings 2 to name a few and I bet other regiments do the same.
Personally I believe the 52nd have a lot of older members and will be a good choice, different regiments have different highs and lows, the best bet would be able to search around and have tasters if you will, see which regiment fills like the right place and stick there, I wish you the best of luck!