.8 mm caused my Glock mags to go nuts.

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HOOfan_1

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I thought I was going to have to throw out some of my glock 9mm mags..none of which has likely had more than 600 rounds through them.

Last time I went to the range I was having problems loading them all the way and the spring seemed to be acting funny. I ended up taking them apart (huge PITA with Glock Mags) and cleaning them well.

Fast forward to the most recent range trip and I just could not load the 15 round mags full. And even partially full I was having feeding problems...the rounds were actually getting stuck way down in the mags. The 17 rounders were not causing quite such a problem....but were still causing problems.

My dad suggested comparing the more recently loaded rounds with some of the older rounds, maybe the OAL was too long and they were rubbing in the magazine. So I put them on a flat surface, and I said...the rounds giving me a problem seemed to be a little longer...maybe a millimeter. It is kind of hard to see a millimeter worth of difference with round nose bullets.

The shorter rounds loaded just fine. Get home, take the calipers to the longer rounds and they are .8mm longer. Apparently the seating die has worked its way loose.
 
For a minute there I thought you were going to say that there was actually something wrong with a Glock.:what::D Seriously the smallest of things can cause a big problem with a firearm. I am constantly amazed that the commercial ammo will work in almost anything (even though not always the "best" choice) with out causing problems. Part of the reason that it is only OK when using it for accuracy. Lucky indeed is the shooter that has a firearm that is most accurate with factory ammo.
 
The shorter rounds loaded just fine. Get home, take the calipers to the longer rounds and they are .8mm longer. Apparently the seating die has worked its way loose.
Click to expand...
One reason we check everything when starting a new batch. Flaring, seating, crimping, etc, to be sure it is what we mean it to be, and matches our notes from the proven batch.
 
How big is a .8mm?

Some of us are metric challenged, and use thousands of an inch in all reloading measurements.

rc
 
.8mm is .0008in. Almost, seems as though something that small is insignificant but obviously not. I stand corrected. It is 0.03149597in. In my haste I plugged in the the values for mil. instead of mm. Thanks for the correction and I will be more careful in the future.
 
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When troubleshooting a problem, if the problem appears in multiple locations at once (the mags), then the problem isn't likely wto be the multiple locations. It will be something they have in common. In this case, that would be the ammo and the gun itself. Your first direction to look, then, may be to see what has changed. In this case, ammo would be the likely choice, though the gun is still possible.

Just something. To keep in mind for the future.
 
The gun couldn't be at fault when the rounds were sticking in the magazine and I had to bang it on a table to get them to come out.

It was the ammo
 
I concur. 1.0mm=roughly 0.0393in

0.8x0.0393=0.03144in

I work with sheet metal for a living. Normally 1/8th of an inch is "close enough" for every measurement but recently I was building a product for nuclear power plants. Everything was in millimeters. Everything we measured had to be within 1/4mm as the finished/assembled parts could be no more than 3mm out of spec. total. Major PITA!! Machinists and reloader a should be used to being more precise but mills, lathes, and reloading tools tend to be much more precision oriented than sheet metal tools.

Now the OP has to go back to his press and figure out why some of his completed rounds are coming out too long to feed reliably through the magazine. What type of press, dies, and components are being used? The likely cause is the seating die working loose, as he mentioned, but there could be other issues as well.
 
I had the same problem with some 45 ACP LSWC'S in my high cap mags for my M & P. The standard mags worked fine.I also took my mags apart and even sprayed some silicone in them, but no joy. Seating them just a little deeper cured the problem.:cuss:
 
SAAMI spec for 9mmx19 is 1.169" max OAL.

Most ammunition is fabricated with some margin on that limit.

Factory FMJ 124g is typically around 1.150 (or so).
 
A friend had a Glock with magazines that would bind out on 1980s Norinco 9mm ball.
They were simply too long. I don't recall the measurement, unfortunately.
Shot fine in his Sten gun. (Live and legal.)

If you just take a millimeter as 40 thou, you will not be far enough off to affect most shooting measurements except for fine stuff like bullet diameter and casehead expansion.
 
If you changed bullets, the ogive on the longer ones may be different, and the seating stem is contacting a different spot on the bullet. Ideally, the seating stem will be contacting the nose of the bullet, but if it doesn't, then the sides of the bullet become the contact point.

Hope this helps.

Fred
 
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