Have you cleaned 17 round mag?

 

Umm..... No. I have never cleaned any of my mags. I didn't know that was a thing. Do I just take it apart, clean the mag and the spring with normal solvent, then put it back together.

With that said, it looks very clean and new, but I'm willing to give it a shot.

 

If you insert the 17rd mag and pull the slide back does it lock back? Not shooting, just manipulating the gun empty?

If it does, more then likely the mag is fine and you grip is interfering with the slide stop, preventing it from locking back during firing. The reason it doesn’t happen with the 20rd mags is they have heavier/stiffer springs then the 17rd mags and they’re likely able to overpower your grip interference with slide stop.

If the 17rd does NOT lock back with dry manipulation, then likely the springs are worn out and/or mag tube (inside of mag) is dirty.

 

It does stay open if I pull it back. When you say it's my grip, do you mean the way I am holding it, or the grip on the gun?

 

I don't see how that is possible. I just looked and my hand or thumb don't come close to it.

 

Follower pushes slide stop when empty and that locks the slide back. In your case follower is engaging slide stop and spring is strong enough facilitate that. So the only missing variable is live fire/recoil.

Likely under recoil either the gun or your grip is shifting and interfering. Easiest way to test is to simply shoot it strong hand only.

 

Can you take pics of the mag and upload them?

Taking apart 2011 mags is a common normal thing.

 

Is it a Gen 2 or Gen 3 staccato mag, and when you say used, does it have high round count?
Reasons this could happen:
1. The magazine spring could be getting worn out (would take 20k+ rds, my gen 2 staccato mags have 15k+ on them with no issues in a staccato or atlas)
2. The follower could be getting worn out which is extremely rare but it is possible
3. You could be using under powered ammo to where the slide is barely cycling
4. Limp wristing the gun to a certain degree, although if it's locking back on other mags then it's probably just the one mag
5. Feed lips are bent and follower isn't going all the way up, although if this happened you'd probably be seeing other malfunctions but just throwing that in there.

 

The magazine follower is the same in your 17 and 20 round magazines. Swap the 17 round follower with one of your 20 rounders. If the problem follows the follower to the 20 round magazine then you know the issue is the follower. Call Staccato and they'll probably send you a new follower.
If you swap the followers around and the problem goes away then pat yourself on the back and forget it.
Always try the simple stuff first.

 

I wanted to update everyone. I swapped the follower from the 17 --> 20, and tugged on the spring a little. I also cleaned the mag. One of those solved the problem, can't say for sure which one, but at this point I am good.

 

Good info to know, picking up a C2 tomorrow.

 

I had some gen2 Staccato 17rnd mags that did the same thing and they were new along with the P DPO. I just ordered some of the 20rnd mag springs and installed them in the 17rnd mags and problem was solved and I have about 1200rnds down between the 3 that I did that to and haven't had a problem with the slide locking back since I did that. Stretching the springs is just a temporary fix if they are old and starting to wear. Just call Staccato and see about getting some new 17rnd springs and followers they may send you some, if not just go to DAWSON PRECISION and order them.