Bolt does not lock after last round fired

[Lunker]

This is on a Ruger PC-9 Carbine. I have tested with four different magazines, so I know that it isn't a mag issue. I just bought the gun so i can't say 100% whether this is a new problem. The seller assures me that it never happened for him, but also that he hasn't shot it in a long time (why he sold it to me in the first place). I believe him. As a side note, the gun's insides are really grimy and filthy. I took it apart and will give a thorough cleaning. Hopefully that solves it. Does anyone have any suggestions? Is there anything I should look for in the slide lock that could be malfunctioning? Are there maybe different versions of the recoil springs, like one for regular and one for +p and +P+ ammo? Perhaps I have the very stout springs. The action does require a fair amount of force to pull back. I have the ghost ring model, if that makes a difference.
Thanks in advance.

 

[precision_shooter]

If i'm not mistaken it does not have a bolt hold open after the last round. Much like a Ruger 10/22.
So if I am right in my thinking, it's not a malfunction, but can be a neusance if you are used to shooting auto loading rifles that lock open after the last round.
Not sure if there is a conversion to make it lock open or not. I'm sure someone with a little more knowledge than me can answer that.

 

[Lunker]

The reason I know it should stay locked open is that I owned another of these rifles (and stupidly sold it) and it locked back on the last round. Strangely though it did not lock back when an empty magazine was in the rifle and the bolt was pulled back.

 

[TerminalVelocity16]

I would definitely completely disassemble the entire rifle and clean it out. Theres no reason for an empty bolt to be that hard to open. So my first guess would be a lot of fouling in the action. I'm not exactly familiar with that model but if it is gas operated one thing to check would be to make sure the gas port, make sure it's not clogged up. If it's just plain inertia operated then yeah I'll go with dirt. if none of that works, then the main spring could be new, in which case it needs to just be worked in enough so the gas/inertia is enough to open the bolt enough that it locks. Had a similar problem with my M1. turned out to be a combination of new springs and a loose gas plug. hope it all works out.

-Term

 

[Lunker]

The gun is just recoil driven. No gas ports to the best of my knowledge. The grime in there looks like automotive grease. It's that whole next level of filth that keeps your hands dirty for a while even after a few scrubbing, like the inside of an engine compartment. That's a good idea about the spring though. Maybe I just need to shoot a lot more. If the cleaning doesn't do it, I will make some hot reloads and see if that is enough to lock the bolt.

 

[TerminalVelocity16]

ok yeah. Like I said had almost the same problem with my M1. for the new springs, I just sat around watching tv just working the action over and over to get the springs worn in, and plenty of rounds. But get all that crude out of there first. sounds like the previous owner supplemented cleaning the rifle for just dumping some grease in and hoping for the best.

-Term