STI mags won't lock in

[assaulter]

So I bought 6 new STI Magazines from Brownells for my 9mm Eagle. Two of them insert perfectly and lock into the mag catch with ease. Of the remaining 4, two of them just won't seat and the other two will seat, but require an amount of force that it completely unacceptable for competition use. I called STI and their voicemail inbox is full, so I sent an email with no reply yet.

My thought is that the notch on the magazine needs to be opened up at the top, but before I go filing on nearly $300 of gear I'd like to hear some thoughts on the matter. I have tried these on my Edge too and got the same results.

[earplug]

I had a issue with another brands base pad keeping a magazine from seating. You might try checking there, and swapping them around.

You could try measuring the magazine catch cutout location and size and comparing them with good verses bad units.

[louu]

I think Atlas gun works made a video on this. I had the same problem and had to clean up the rough edges on the bottom of my frame.

[assaulter]

It's definitely not the basepad, this is happening even with tubes with no guts.

[assaulter]

I just watched that. I'll check those dimensions on the mags.

I think Atlas gun works made a video on this. I had the same problem and had to clean up the rough edges on the bottom of my frame.

[glassblower]

I've used Dawson Precision mag tuning kit for both 9 & 40 and all my mags fit nicely. Are you using a 9mm spacer in your mags? If so, be sure and check the length of the spacer as it could create a fit problem.

[assaulter]

No spacer in these yet.

[LowSpeedHighDrag]

Don't know if it's the same problem you have, but I'll tell you my issues with some STI magazines.

I bought a DVC Limited in 9mm, which came with 2 126mm 10 round mags (thank you, MA). Both worked perfectly. I then purchased 4 additional magazines from various sources. All 4 had issues with locking into the frame. They would work, but only if inserted with a lot of force.

I found that the top part of the magazines, above the magazine catch notch, were out of spec compared to the ones included with the gun. Each one had the tube more squared off than the ones that worked. Wound up having to reshape the magazine bodies by using a vice and a brass mallet to tighten up the dimensions. Took a while, but finally have them working.

Sounds like STI doesn't always make their mags correctly.

[scottlep]

Measure the mag catch slot in the mag body on the mags that will seat versus the ones that won't. I had an issue a while back where the slot was too small and mags would not fully lock in causing the mag catch to not fully engage and then would not allow me to pull the trigger since the overtravel screw was not hitting on the correct part of the mag release.

Here is my thread about it back in 2013 - http://www.brianenos.com/forums/index.php?showtopic=182627&hl=sti+trigger+hard+to+pull

Might not be the same issue you are having, but worth checking.