First of all, I think the caliber of the Walther is .380 acp. or 9mm shurz, .308 is a rifle cartridge.
You'd be better served with a 9mm luger, IMO. The pistol may be a little larger; however, ammo is more readily available and cheaper tham .380. I'm mighty partial to my XD 9 SC. If you find one, it'll run you about $500 NIB.