Mec-Gar 10 round 9mm magazine MGCGOV910AFC

[niemi24s]

You're spot on with the 9mm being worse than the 45 Auto gap under the top round. The mid-SAAMI specs for the included tapers are 0.017"/in. 0.018"/in. for the 9mm but only 0.0024"/in 0.006"/in. for the 45 Auto.

Whoop-de-doo, huh?

Happy shootin'

[Steve in Allentown]

As long as we're on the subject, the .38 Super is a straight wall case with no taper, if I recall correctly. If I'm right, that would mean the Super would have the least amount gap between cases and the first round out of a fully loaded Super mag would strike the frame ramp higher than either the 9mm or .45. Am I singing the right tune on this?

[niemi24s]

Yes, as far as the case having zero taper. However, the rim of the .38 Super has a diameter 0.020" greater than the case mouth diameter. That gives the whole case an included taper of 0.024"/in. - the largest of the three.

FWIW, using the mid-spec SAAMI values, all three of these cases have rim diameters greater than any part of the case ahead of their extraction grooves. When on a flat surface, such a case will make contact at the case mouth and the forward part of the rim.

Of course, all this stuff pertains only to factory ammunition and not handloads. F'rinstance, my 0.453" OD cast lead .45 wadcutters seated in good thick brass with 0.011" thick case walls will have a case mouth OD real close to 0.475" which equals the mid-spec rim diameter. That gives such a case a taper of zero.

[Sorry for the math errors in my previous post]

[niemi24s]

All that stuff above is just for one cartridge all by itself. But when when there's a magazine full of them, the gap between the top one and the one below also depends on the magazine feed lips and whether or not the rim of the top cartridge is nestled into the extraction groove of the one below.

I could probably do all the calculation necessary in a few hours for the 45 Auto in a 1911 magazine, but with no data for the 9mm or 38 Super magazine - why bother. Sounds like a good empirical experiment for somebody having all three magazines and ammunition.

[PolyKahr]

I have used Mec-Gar mags for my .38 Super. The gun ships with Mec-Gar and I bought a number of others. Never had a problem with them.

[Rick McC.]

Even though I'm totally unfamiliar with the 9mm and ramped barrels, I've a sneaky feeling that this followers feed ramp is merely a PR gimmick. Steve's photos show bullet nose contact down at the bottom of the barrel feed ramp which is probably made by the first round few rounds fed the full magazine. And just like the GI 1911 in 45Auto it's all due to the gap between that top round in the full magazine and the round below it - which is a result of the angle of the magazine tube. The followers ramp is near the bottom of the magazine tube when those first few rounds are stripped from a full magazine and their low strikes on the barrel (or frame) ramp are the result of those rounds getting rotated down on top of the round below when struck by the slide when fed.

Just like in a 45 Auto 1911, the follower is too far below and aft of the top rounds to have any supporting value except to hold them up under the magazines feed lips. But as the magazine empties, the follower moves up and forward and will eventually close the gap between the top round and the round below it.

I further suspect Steve's gun will feed flawlessly with this magazine even if the follower didn't have that ramp. This shows what I've found to be the case in a 45 Auto 1911 and suspect the 9mm version will be very similar:
Attachment 6454
Coincidentally, this also explains why the top few rounds from a full magazine suffer the most bullet setback. On the other hand, the last few rounds suffer the least bullet setback as the follower is forward and high enough in the magazine tube to eliminate the gap between the the top round and the one below - so it doesn't nosedive and hits higher up on the frame or barrel ramp. The 45 Auto strike patterns below are similar to those in Steve's images:
Attachment 6455

Well; they actually do work.
10 round 9mm 1911 mags have a serious propensity to make the first round or two nosedive; particularly in mags that are anything but well broken in.

The second gen Wilson ETM 10 round 9mm mags are lightyears ahead of what had been done before.
They stopped the nosedives.