Now that you own a 9mm H&K pistol you might want to consider a .22 LR pistol. However I'm going to go against the grain and not recommended the Ruger. I recommend the Browning Buckmark Camper. The more affordable model of all the Buckmark variations and a very solid little pistol ideal for plinking and just having (safe) fun with.
Those who beat their swords into plowshares usually end up plowing for those who didn't. Ben Franklin