Any 69 series Smith will accept series 59 magazines. The 69 mags are 12 round and come with a plastic butt plate flared pinky rest. Third generation 59 mags are 15 round and they will stick out only about half an inch from the butt. I usually carry my 6906 with either a 5906 15 round magazine or a Mec-Gar 17 round magazine in it. At home I often put a factory or a Mec-Gar 20 round magazine in the gun. You can put a flat plastic generation 3 butt plate on your 12 round 69 magazine to get a shorter over all gun that will hide even better, with no loss of 12 rounds. Just curl your pinky up under the base plate. They are available from S&W for about $3 each.

My second ever pistol was a S&W 459. I love those old 669 pistols. I well remember when they came out. They were nick named "mini guns". They were amazingly small for guns that held that many rounds! You have a darn good gun that will serve you well.