PTR 9CT / AC Unity Mag Issue

[Skandar]

Just picked up a PTR 9CT, and got two AC Unity 30 round mags to try.

The gun runs great and is accurate (though I need to run out and get some forceps to adjust my elevation...just can't make the tool work), BUT...the AC mags don't lock in. They're a VERY tight fit, and feel that they've locked, but after my first half dozen shots or so on each mag, they would fall out of the gun every 3-5 rounds (on the plus side, both have now been dropped 3 times on concrete and don't show any damage).

To confirm, I'm doing bolt open loading, and have tried both with loaded and unloaded mags. I can manage to pull the mags out by hand if I rock them but it takes an effort, so I'm surmising that the recoil is generating enough rocking motion to unseat the mags and the loaded weight is enough to drop them.

By comparison the supplied ETS mags lock in fine and won't come out without definitive action of the paddle / button.

I'm wondering if the issue is the mag not inserting far enough and could be cured by sanding the pad on the front of the mag slightly.

New German metal mag on order as a definitive test, but my feeling is the issue is the AC mags not the gun.

Anyone else have this experience and am I moving in the right direction?

 

[Vinz Klortho]

I had a similar problem with my C93. I bought some new, German mags and they wouldn't lock in without applying an amount of force that made me nervous.
An intelligent person would have removed the 20 dollar magazine catch and sanded on the upper edge slightly.
I chose to grind on a seventy dollar magazine because, well, let me refer you to the previous line.
I took a little material off the highlighted edge (raised it) and it fixed my problem.

 

[spartan]

Sand down the back tab. Keep taking a little off, test fit, and repeat. If done properly you can get then to lock up tight with very little wobble.
Best of luck!

 

[Skandar]

Appreciate the replies.

I took the mag that was failing with less force applied and worked on it first. Tried Vin's fix taking a little off the top of the catch recess on the mag. Oddly that seemed to make the situation worse as the mag pulled out with very little force (no judgement on the advice...it LOOKED like it would fix the problem). Then I tried Spartan's advice on that same mag. Again, even worse than before. Completely perplexed I tried taking some off the pad at the front of the mag which made no change at all.

Looking carefully at the second mag, it seemed to be engaging correctly so I didn't sand down the top of the recess, but just kissed the back of the mag with some sandpaper (Spartan's fix). Voila. That mag now fits like a glove.

I'm guessing that I was too aggressive with the first fix on the first mag, or that I just got a bad combo of PTR tolerances and AC Unity tolerances.

Not sure if I'll try another AC Unity mag. Nothing against them, but will be trying KCI gen 2 along with a genuine HK shortly and will fill out the kit from there.

Oddly, the ETS mags still fit great. Going to do some more function testing on them but they may actually make it into the rotation.

Thanks again for the advice!

 

[Skandar]

Ok, so further update.

AC Unity mag held great...empty. Got to the range and inserted a loaded mag and...mag pulled out with only moderate force, with the bolt still open. I imagine there's more I could do at this point, but just gave up on the AC Unity. ETS mags now have 125 rounds a piece through them and are working like a champ. No failures of any sort on either.

Guess the AC's and my PTR just don't mesh.

 

[AGG]

Ok, so further update.

AC Unity mag held great...empty. Got to the range and inserted a loaded mag and...mag pulled out with only moderate force, with the bolt still open. I imagine there's more I could do at this point, but just gave up on the AC Unity. ETS mags now have 125 rounds a piece through them and are working like a champ. No failures of any sort on either.

Guess the AC's and my PTR just don't mesh.

Thanks for the update.

Tony

 

[jorayr97]

I had 4 of the AC Unity mags and they were all a very tight fit. I sanded the front pad on 1 of them and it was easier to insert but took too much force to lock it in. I decided not to mess with it any further and wound up selling them. I use the KCI gen 2 and MKE mags in my clone and haven't had any issues.