BTW: The pic of the wedged rounds is actually the way it failed at the range, it still has the cam follower spring pressure in the mag. Photoed when arriving home.
Thanks so very much to each of the you folks responding!
The pistols are Czechmate's ? purchased a couple last year.
I'm just going to go ahead and babel a bit here, hoping that I touch everybody's kind comments.
1SOW... Thanks for the heads-up on using the Mona Lisa icon!
My mags are always dis-assembled and cleaned after every match, whether I used them or not. Reason being is that sometimes there is sand and dirt blowing around in the air and it tends to migrate into my range bag. The inside of each mag is mirror shiny after cleaning and before re-assembly. All powder residue is completely removed. Magazine cam follower, spring, floor plate and plastic mag sole plate is cleaned ? there is no piece that isn't sparkling before re-assembly. The failure mode shown is an a clean mag and is one of my 28 rounders that can only be used with 27 rounds. The mag shown is a 27 rounder and it failed in my first stage last week. It's been used quite a few times and failed once before in similar fashion. It now has a big X on it. 1SOW ? boy, I'd sure like it to be a dirty mag causing the problem though!
IDescribe ? Yup, Mags are super clean. The 20 rounders, of which I have approximately 20 each, it has happened twice, the exact same failure mode, but I failed to mark them thinking that it was just a fluke. I have enough mags such that I don't have to reload mags between stages and if there is a problem, the problem mag is dumped in my bag and is evaluated when I get home with the failure.
Yes, there are magazines that are reliable, most of them as a matter fact ? I have checked each attribute against the other that I thought could cause the mag feed issue. With my measuring equipment, a mike and a dial caliper, there is dimension spread of up to .002 inches in three of the mags ? all other mags, including my big sticks measure, nominally, .866/.867 up to the transition to the feed lips. Frankly, I've never seen such close attention to manufacturing tolerance control. If it's geometry causing the problem ? I'm lost.
All my 20 rounders are CZ factory, no changes. The big sticks, which tend to fail more than the 20's, not just for the problem noted here and don't know where to start, other than what I'm showing. Each big stick has the CZ Custom guts in it which allows (Most of the time.) pretty reliable feeding. But I have had the cam follower roll over inside the magazine more than a few times. That is easy to understand, though.
Bossgobbler ? As far as I can figure currently, I'll shoot 10-12 rounds with this type of failure and only happens when I shoot very quickly with the big sticks. Haven't tried loading anything less than max.... yet. Stuffing the last round in the mag is a bit of a trick but found a slick way to do it with very little pressure. I'd use one of those thumb buster tools but have found they tend to damage the cases periodically, at least when I use them. I have one but it stays in the bag... for now.
Stuart ? All the 20 rounders are factory stock just as I received in the case with the guns. Having said that, the most problems come with the big stick, so I have somewhat disregarded the few issues I've had with the 20's.
All the mags are marked:
On the big stick mags they do exactly as you describe, the rounds will periodically bind. No binding with 1-2 rounds. So, I put one of the big sticks in a machinest's pin vise, nice parallel jaws, which captures about 4 inches of the mag tube. (Mags disassembled.) I squeezed the mag body by .005 total, making the body .861. Checked the fit in the gun and had slight binding on the front and back walls when inserting the mag body, so a slight squeeze on the front and rear walls solved the fit-up. Unfortunatly, the cam follower no longer rises to the top. It stays about .060 low and does not operate the slide catch, plus the top last round is a little bit floppy in the mag. I'm thinking .005 might have been to much. I'll keep working with it.
Having said all this, I should also mention that I have reworked and polished all magazine lips so that I can shoot 1.155 -1.160 length ammo (Actually, any length cartridge and bullet style combo that I chose.) The 20 and 26-27 mags as shipped had terrific failures to feed shooting SAAMI spec ammo due to the mag feed lips holding on to the round. Literally, every round attempted to feed but would dive or would hit the barrel feed ramp and set the bullet back in the case. I did the math and figured the feed lip cartridge release point had to be .421 from the rear wall of the magazine in order to feed 1.160 length cartridges. Lucky me ? it worked! A small amount of barrel feed ramp polishing and no more failures to feed with SAAMI spec length cartridges. I should qualify that a bit.... 1.160 with round nose bullets. I can't see that this would cause magazine tube failures -- I could be wrong!
I had read somewhere, perhaps on this forum, don't know for sure, that the cartridge OAL for the Czechmate should be no longer than 1.15. That OAL was literally a failure to feed for every round, no kidding ? it didn't work at all. So I went back to the mags to find a fix and arrived at feed lip modifications, no angle changes, just cartridge release point.
Okay, I've tried the squeezing thing and will try it at the range as soon as possible... sometime in the next week or so.
I'm wondering about going back to the original CZ long spring and cam follower for the 26-27 rounder?
