I think the Ruger PC-4's and PC-9's are nifty little carbines. I have never owned one, but have been around them a bit. They seem to be pretty decent guns, reliable and surprisingly accurate (the ones I saw had ghost ring sites). The last one I saw was about a year ago in a gunshop, they were asking only $350 for it. So the $400 may be a little bit pricey for a used one. But the price may have gone up a bit since then. Evidently these guns have become quite popular with metro police departments as "cruiser carbines". If they are half the guns that the Ruger P-series pistols are, you will like it. I can't remember the exact issue, but Guns Magazine did a detailed story about these carbines within the past 1-1.5 years. Might look through some old copies if you have access to any.