Monday, February 5, 2024

Downloading magazines for reliability


We've spoken before in these pages about the advisability (or otherwise) of downloading higher-capacity magazines by a round or two to increase firearm reliability and keep magazines in good condition.  I'm a fan.  I was taught in the South African military to download by plus-or-minus 10% for routine carry.  Thus, 10% of a 35-round R4 magazine would be 3.5 rounds:  therefore, it would be loaded with 32 rounds for routine everyday carry.  The older R1 rifle (a license-built version of the FN FAL) had a 20-round magazine, which I usually carried with 18 rounds in it.  In a combat area, where a fight was more likely, we'd download by only 5%, and some would load right up to capacity (although I never did, preferring to reduce the strain on the magazine spring and ease the cycling of the bolt).  I've continued the practice in civilian life, downloading most higher-capacity magazines by 5-10% on a routine basis.

(Another common practice in some military units was to load tracer for the last 2 or 3 rounds in the magazine, to provide a visual warning to the shooter that it was almost empty and he needed to reload.  I didn't do so, as the line showing the passage of a tracer bullet points right back to the shooter, and I didn't want to make myself an even more visible target, particularly at night.  Also, in bush warfare in Africa, tracer bullets had the upsetting habit of setting fire to dry grass and leaves - not a good idea if the prevailing wind blew the resulting bushfire in your direction!  In one incident, a fire started by a patrol during a firefight didn't bother them, but gained strength over the following day and intercepted their resupply truck that evening, destroying it and its cargo and forcing a premature end to their excursion.  There was a certain amount of consternation and monkeyhouse over that, particularly from the infuriated truck crew . . . )

In answer to a reader's question about functioning problems with fully loaded 17-round SIG handgun magazines, a recent article discusses the downloading question more fully.

The top round in a loaded magazine contacts the bottom of the slide when the slide is forward and the magazine is fully inserted into the magazine well of a semi-automatic pistol. Although there is normally friction on the bottom of the slide from contact with the top cartridge in the magazine, it has minimal effect on the movement of the slide if the ammunition stack can compress slightly back into the magazine body against the magazine spring. If there is no room for the ammunition stack to compress, the friction resistance of the top cartridge in the seated magazine is too great to allow the slide to cycle properly, which causes the phenomenon that you are experiencing with the slide failing to fully cycle.

I would first suggest that you load your magazines to their capacity of 17 rounds, and then apply pressure to the top cartridge with your thumb. The cartridge should move against the magazine spring until it is visibly clear of all contact with the feed lips at the top of the magazine. This small space is necessary for the magazine to seat properly in the magazine well, and also for the gun to cycle properly and shoot reliably.

If you download your magazines to 16 rounds, I suspect your gun will exhibit the reliability you expect from it.

This phenomenon is not only limited to pistols, but should also be considered when loading and topping off any firearm utilizing a spring-loaded, box-type magazine. For example, it is a somewhat common practice to download an AR-15-style rifle magazine (particularly military-surplus magazines) from 30 rounds to 28 rounds to enhance reliability by ensuring the magazine will seat properly in the magazine well and the top rounds in the magazine will flow through the gun without causing any restriction or stoppage.

There's more at the link.

I believe the practice also extends your magazine's life, in that the spring is not kept in a fully compressed condition for long periods.  I know many assert that modern magazine springs won't "take a set", as it used to be called, and be weakened by this;  but I've had some older magazines that did, even from original equipment manufacturers.  Third-party magazines. and some of Third World manufacture, may exhibit the problem more often.  For example, I can't comment on their more recent production, but in my experience some older magazines from ProMag and KKK appeared to suffer from that issue.  (YMMV, of course.)

Food for thought for those among us who rely on magazines to feed our firearms.



Andrew B said...

I own a full-size SIG 320 pistol in .40 caliber. The magazines, allegedly, hold 14 rounds, but my arthritic hands have never been able to fit more than 12 rounds in any of them. Even with a loading device, 12 is about it. I guess the Universe is telling me that I will have to make do with a dozen in each magazine. Thus the downloading is taken out of my hands. Literally.

Paul Chappell said...

When I was in, we regularly loaded out 30 round magazines for the M-16's to 28 rounds with live ammunition. If we were playing war games and had blanks we'd usually go 20-25 rounds, but the blanks were just problematic on every level.

For sidearms the 1911 magazines were usually older but higher quality for some reason. Maybe only HAVING 7 rounds it was fine, but they the GI magazines worked well. While we officially transitioned to the M-9, almost all of us kept the older 1911's, at least unofficially. Civilian side, I do tend to drop a few rounds off of the standard load, was not sure if that was just old GI habits, but found fewer issues with the weapons cycling so no reason to change it I suppose...

John in Philly said...

Downloading pistol magazines.
Both INS and Homeland Security policy was to load pistol magazines to full capacity.
No issues with the Beretta .40 caliber 96D and no issues with either of the two .40 caliber HK pistols that I carried.
They changed to a Glock 9mm after I retired and it is also loaded to capacity.
Both of our EDC weapons are a single stack 9mm and due to aging I agree with Andrew B.
I was also having trouble with forcing the last few rounds into pistol magazines.
This got a lot easier when I invested in an Uplula universal loader device and it has worked great for us.
I don't download our pistol magazines.
But I do download our AR magazines to one less than full capacity.
This makes it much easier to lock a full magazine into the weapon and stow the weapon with a chamber flag and the safety in FIRE.
I'm probably going to invest in an Uplula rifle magazine loader.

1chota said...

Lessons learned: Fully loaded modern magazines won't malfunction if fully left fully loaded. some of the older M16 mags were basically throwaways. even tho that didn't happen. they were pretty much cheaply built.
I did find out that it is possible to over insert an AR/M16 mag with the bolt locked back. probably one of the reasons to tap and tug.
I long ago ground the back lug of the follower off of my competition mags. End of problem. An over inserted mag is a real booger to correct. sigh.
Same thing can happen with 1911/2011 style mags. Way faster to drop the empty mag after the 'click' than to fight an over inserted mag on the clock.
I would think that in the midst of a serious disagreement the time factor would enhance the pucker factor. Also, mags are cheap. Check the feed lips. If they are showing wear, dump that mag in the trash.

Anonymous said...

Downloading is typically more important for tactical reloads than emergency reloads. And tilt to lock mags typically less of a concern than vertical insert to lock mags during tactical reloads.

Also mag stack also affects % needed. Staggered you typically need 2 rounds to equal one round in height vs. single just one. Gun cycling design also affects how much rounds get depressed as does diameter of cartridge/caliber...

For combat and reliability, you're also accounting for dirty gun, worn springs, etc., potentially providing add'l impediment too, including potentially across all guns in your unit...

Point being as much art as science as original article touches on with respect to just individual mag variability.

Separately, I would enjoy hearing your thoughts on galil/r4+ series vs. M4gery, FAL, etc., in serious use situations. Don't recall seeing that here previously.

Anonymous said...

Do whatever you need to do, including enlisting others to load mags to capacity when new to you and let them sit for a spell. If they don't take advertised capacity, manufacturer should replace under warranty.

Anonymous said...

we where taught to down load our magazines back in the 1/503 rd. a very long time ago. something I still do to this day.20 round magazine gets 18 and so forth.
pick up a bunch of used Sig 226 magazines a few years ago for 6 bucks a pop. replaced the springs and cleaned them up for 1/4 of what new factory magazines cost. tested them out at the range and no problems at all.
check out Wolff gun springs. nice people and fast shipping
too. one can never have too many magazines for your weapons
one tends to "lose" a few when times get "sporty"
dave in pa.

selsey.steve said...

I am not a shooter nor am I a fire-arm owner (I'm not legally to be one here in Englandistan) but, as a metallurgist, I can assure you that springs do, in fact, take a 'set' as you call it. Almost all ferrous-based metals do this when given sufficient time when compressed in one position.

clark myers said...

As noted round count is one more variable to worry about. After trusting and verifying and qualifying an extra round magazine in say a 1911 I might worry about sharing a qualified in my own pistol extra round magazine for use by somebody else in a different magazine just as I might be nervous about having to salvage loaded magazines myself. The springy Chip McCormick style follower feels different and there are other trick followers and tube extensions and springs that make universal judgment difficult. I routinely look closely at and gage feed lips that might have been hammered apart by today's high powered magazine springs. Myself I carried a 9x23 in part for reliable extra capacity in the same size package.

One consideration in rifle magazines, especially to my mind .223/5.56 normal capacity magazines - and other military style cartridges in gas rifles, is consistency in loading top cartridge left or top cartridge right. Some people might insert a magazine in a rifle with the bolt open and drop the bolt - not fires from an open bolt of course - then drop the magazine and feel which side the top cartridge is on to be sure one has fed into the chamber.

Anonymous said...

Ried Hendricks of Valor Ridge Training believes mag wear is a matter of loaded cycles, more than spring set. A full 30 in ARs and AKs, then Replace as needed. My gen.0 Glock 17, bought in the 80s, with 3 spares to back up the 2 that ame with it. Always full loaded, all work fine, so far. But I have acquired more....some are left empty. Guess it's dealers choice, as long as you keep the weapon and mags clean, and with proper lubrication...

Will said...

My beef is with Glock mags, specifically the g27 oem ones. Rated for 9 rounds, only 25% can hold that. Eventually I installed Pearce Grip 2733 extenders, which brings all of them up to 10 rounds, since they were designed to add two for the 9mm version. So, the 8.5 round ones will get to full cap with the extra space they have.
I've tried to determine the problem, but haven't found any obvious dimensional differences between them with hand held measuring tools. Even swapping the base plate parts and springs doesn't change the capacity, so it seems to be a subtle variable in the plastic/steel liner mag body.

Stuffing the 9 rnd oem mag leaves it with no vertical compression space, so seating that with the slide closed requires a forceful smack, but it cycles okay that way. Not optimum for real world use. The PG bases gives me a full hand grip, a maximum legal mag, and a user friendly reloading situation for most all contingencies.

Needing to reload in a civilian gunfight is not a common scenario, but it IS more likely for a left-hander, due to loss of mag after the mag release button gets bumped during carry, since it is facing outward. Having the mag drop free while sprinting for cover after drawing is somewhat disconcerting! The weight change in a gun is noticeable when you loose a full mag.