Tuning CZ mags

[djcantr]

I searched and didn't find any information on tuning CZ mags. I did, however, find a good thread on tuning STI mags. http://www.brianenos.com/forums/index.php?showtopic=141880 I have a new CZ Tactical Sport on the way that will be here Friday. Have everything ready to go, including some mags with CZ Custom extended base pads and Grams followers and springs. I wouldn't do any tuning until I test it out first, but want to know where to start if I need to.

I have a few questions:

Do CZ mags generally require tuning, specifically CZ Tactical Sport mags?

In the thread I linked, the OP stated he likes to set the feed lip spread to .388 +-.004. Should that same spec be used for CZ mags? Two of my mags measure .380 and .382 evenly across the depth of the feed lips. Another mag .379 at the front and .383 at the back. Fourth mag .379 at the front and .384 at the back.

I can get 20 rounds in these mags very easily. I can fit 21, but I'm really, really cramming in that last round. Will these likely loosen up or may they require a little squeezing in a vise like the STI mags in the linked thread?

Are there any other modifications or tweaks that CZ mags might need?

Thanks

[JimmyZip]

I never tweaked my mags and just ran 20 reloadable with the CZC basepads. I got some new springs from Stuart when I first put them together. They ran well the whole time I had the pistol.

[CDPMatt]

Just shoot it....

[kneelingatlas]

I wouldn't squeeze the mags like the 2011 tuning post says because if they already bulge when loaded to 20 and won't drop free. I took some metal off the inside of the frame and polished it; no more problems. If you want 21 reloadable, I think the way to get it would be to trim a coil off the spring, though I'm not going to risk it.

[djcantr]

Thank you guys for the input. What about the feed lips? The mags don't all have the same measurement and a couple vary from front to back between the feed lips. What width should I tweak them to?

[gator098]

only other thing to consider would be to polish the outside of the mags, mine have a habit of dragging a little when i push the mag release, a little jeweler's rouge and a buffing wheel on the dremel used on the areas of the mag that show wear goes a long way, HTH

[kneelingatlas]

I wouldn't mess with the feed lips unless you're having failures to feed.

[TXMXRACER]

Mine worked great straight from Angus.

[StevenR]

I can get 21, although sometimes not as easy as other. Once they are in and I tap the mag there will be 2-4 mm of play. With the Taylor-Freelance basepads 20 is their comfortable maximum. Feed lip spacing has not been a problem for the first 10k + rounds.

[blind bat]

I've been tempted to cut the "feet" on the follower of my 18/19rnd mags to see if I could squeeze in another round or two.

[djcantr]

I've now shot about 500 rounds or so through these four mags. No failures to feed, so I'm not really concerned about the feed lips.

I had tried putting 21 in all of the mags and seating them on a closed slide. I could do it, but it required a very hard push and then the mag release was very hard to push in to release the mag. They were so close... I decided to do a little tweaking. I measured the depth of the mags and they ranged from 1.2725 to 1.275 down the length of the mags. I carefully squeezed them a little, measured, tried them, squeezed a little more, measured, tried them until I could seat them with 21 rounds and a normal tap with the palm of my hand to seat the mags. I ended up with them measuring 1.268 to 1.271 down the length of the mag. It was a miniscule change, but made seating the mags much easier. I did have to squeeze back down the width of the mag just in the mag catch slot area a tiny bit. Mags drop free perfectly.

Safety note: I wasn't chambering ammo during these tests but I did remove the firing pin from the pistol while I was checking the seating of mags that contained live ammo.