Ammo rattle with 33 rd Glock mag

[ericire12]

So here is something interesting, I discovered an ammo rattle in my 33 rd Glock OEM mag today.......

The ammo (1 or 2 rounds near the top of the mag; maybe three rounds down from top) is actually freely moving back and forth when you shake the mag.


*If the mag is completely full with all 33 rounds there is no problem.
*If the mag has 15 or fewer rounds there is no problem.
*If the mag has 16-32 rounds in it there is a rattle.
*Ammo is 147 gr Hornady TAP

I shot this mag about a month ago with zero problems. Just thumbing shells out of the mag there is nothing that strikes me as out of the ordinary.

Any ideas? Has to be the spring, right?
 

[Rob Pincus]

It could be the body of the mag deforming under certain pressure (apparently the pressure that is present when there are between 16 and 32 rounds...).

My students this week are using Sigs and one of them had a mag that had rounds rattling loose today. I took the mag from his belt for a demo and it was rattling, but there was pressure on the top round and it worked fine.

It seemed odd at the time but I didn't really think about it until I read this thread.  If you picture the rounds in the mag, there must some deforming of the body that is allowing pressure to be maintained from the spring to the top round while at least one round in between (I would think only one would be possible) to free float....   

I have to think more about the science behind this, unless anyone else has a concrete explanation???   

[Timothy]

Eric, what is the mag material?

Belay that....I looked at the cutaway on the Glock site..

Internal hardened steel case with a polymer covering.  Seems like you won't get any flex in the actual magazine sides.  They should be pretty stable, it may be be flexing but I doubt it and if it is, it's in the tenths of milimeters of deflection.  Could be the follower as well though it makes no sense either.  Strength of materials was not my strong point in school but even minor deflection is enough to allow movement within the magazine.

[DonWorsham]

Does wacking the loaded mag against your palm stop the rattle?

[Rob Pincus]

It didn't with the metal Sig mag!

[Sponsor]

[Fatman]

I have one XD 45 mag that rattles. It only happens if the mag is fully loaded, and i can see the round sitting at the eight hole move forward and back. If I tap the mag on my palm primer side down, the rattle continues. If I rap it bullet side down, the rattle stops, but I have to push the top bullet back into the mag a bit. Swapping springs does not stop the rattle.

The eighth bullet down coincides with the beginning of the diamond shaped indent intended to pinch the cartridges in tighter as the approach the lips of the mag. As near as I can figure, if I rap the bullets forward, the case is held by the indent. if I rap them backward, the indent is off the case and is over the bullet with little or no friction to keep it from sliding forward and back until the case contacts the indent or the back of the mag.  Apparently the 7th and 9th cartridges are in contacting with each other and their respective sides of the mag, with no contact with the eighth round at all.

In my case the solution is simply to  carefully tap the indent in near the eighth cartridge.

[ericire12]

Does wacking the loaded mag against your palm stop the rattle?

Nope.

Its kinda like it is not double stacking those couple rounds properly...... but then the last two or three rounds at the top all line up just fine..... and thus functionality is prefect...... It will cycle through all 33 rounds without any issue.

Ive taken the mag apart and everything looks fine. I have no clue, but it is one of the weirdest things I've seen. Its almost unbelievable how much back and forth play there is with the rounds that are not seated properly.  

[Timothy]

Just don't use it when your in Ninja mode and sneaking 'round in yer "tactical jammies", and slippers.  Might scare em with the rattling mags.....







 

[MAUSERMAN]

I had a mag bottom on my 1911 come off when i loaded it with 7rds. I put it back together and it still works.