Vickers' 50/50 Rule for M4 Carbines

[Redhat]

This is merely proof that even an SME can be wrong sometimes. GI mags were not “properly designed to take 28 rounds” as Vickers states in your link. And I’ve heard Pat McNamara and Mike Pannone say to fill them with 30 in person. Mac even made the comment that stripper clips come on 10-10-10, not 10-10-8.

It amazes me that an old wives take like this is still alive today. I even know otherwise squared away SWAT dudes who fill to 28. Anyone who does this is electing to give up ammo for imaginary reasons. But hey, maybe they have a Leprechaun who feeds their pet unicorn while they’re at work. Some people you just can’t reach.

Actually my intent was to highlight his opinion on Glock Mags. Just couldn't figure out how to narrow it down when posting.

For me personally, I have no problem with 30 rds in a good mag.

[HCM]

So getting back to AR magazines....

There are two schools of thought:

28 rounds vs it’s a 30 round magazine and it should hold 30 rounds. Both are right in context, though the idea that GI Aluminum mags were designed as a 28 round mag is false.

The problem with GI Aluminum magazines is they were designed to hold exactly 30 rounds. There is no extra space nor margin for error. New GI mags in proper condition function fine with 30 rounds. However with no extra room inside the mag box, attempting to insert a full 30 round magazine on a closed bolt often results in the mag not properly seating. The other issue arises when the mag spring starts to wear. It is already on the edge of its operating envelope. Malfunctions are common in all magazines when you try to cram too many rounds into too small a space. The extra space gained by downloading two rounds helps restore a margin of reliability.

Newer designs like Magpul PMAGs have that extra space built into the mag box. This is both the reason PMAGs are 100% reliable with 30 rounds and the reason you can accidentally put 31 or 32 rounds in them. On another note with the USMC and USAF officially adopting the Gen 3 PMAG it also a “GI” mag. The future is now.

We see the same thing with 1911 mags. Cram 8 rounds into an otherwise reliable 7 round mag box and you get malfunctions. Unsurprisingly, 8 round magazines in an appropriate length 8 round mag box work.

Re: 28 vs 30 in Aluminum GI mags- IME people from organizations where magazines are properly treated as consumables tend to fall into the 30 camp. Those who have trouble replacing mags and who have to destroy bad mags to keep them from being re-issued tend to fall into the 28 camp.

[LittleLebowski]

Thanks.

On the topic of loading mag's, I was taught to download them by a couple rounds. But that was in a USMC line company and was probably a good policy for a large group of grunts with various levels of motivation and attention to detail.

Conversely, at Mike Panone's carbine class, he said that he'd load 31 rounds in his carbine in Iraq. 30 in the mag and one in the chamber.

Horses for courses, I suppose.

I learned the same thing in the same place.

[farscott]

I'l just leave this for those interested:

https://www.vickerstactical.com/magazines.html


And FWIW I also agree with this: "This does not need to turn into a tempest in a teapot."

I do disagree with "Leave loaded only when necessary and rotate with fresh magazines monthly. This will increase the longevity of your magazines." In my experience, loading and unloading magazines is what causes the magazine springs to lose strength. Using a magazine is what wears them out, and, as noted, magazine spring and followers are consumables. Magazine bodies, unless the feed lips are damaged or have had a weld fail, can be used with new springs and followers many times. For platforms where magazines are readily and inexpensively replaceable (such as Beretta M9), this is no big deal. But for out-of-print guns, magazines can be harder to source than the firearm, e.g., Norinco NS522 rifle magazines. Five NS522 magazines are worth more than one $500 NS522 rifle. So one learns to keep the magazines running. And those lessons can be used for other platforms. Since loading and unloading magazines causes the wear and the last round is a lot harder to load than the first, I tend to not top off magazines. For example, I often run G17 magazines with sixteen rounds as it is lot easier to seat the downloaded magazine when the pistol is in battery than one with a fully loaded magazine. That implies the downloaded magazine stresses the magazine spring and feed lips less than the fully loaded magazine does. That means my magazine should last longer.

On 1911 magazines, when the magazine starts to stop performing I replace the guts with Tripp Super 7 follower kits. Some of those magazine bodies have had at least five follower kits replaced over the years. I check and adjust feed lips id necessary when I do the follower kit work. I have learned that seven-round 1911 magazines are more reliable than eight-round ones (.45 ACP version, of course).

Of course this is what I do, and I am not an expert. I do hate to deadline stuff that can still be used, so that factors into my habits. Call me frugal or cheap.

[Jay Cunningham]

While this thread is mostly retarded, I’ll say that I’ve both had and witnessed multiple instances of 30 round loaded USGIs AND PMAGs either not lock in on a bolt forward gun or get hung up trying to strip a round off the top.

I load all my 30 AR magazines with 28 rounds, and I download my Glock magazines by one round for the same reasons.

I’ve experienced it myself and seen it happen to numerous other people, both students on the line with me and students of mine.

You do you, though.

[HCM]

I do disagree with "Leave loaded only when necessary and rotate with fresh magazines monthly. This will increase the longevity of your magazines." In my experience, loading and unloading magazines is what causes the magazine springs to lose strength. Using a magazine is what wears them out, and, as noted, magazine spring and followers are consumables. Magazine bodies, unless the feed lips are damaged or have had a weld fail, can be used with new springs and followers many times. For platforms where magazines are readily and inexpensively replaceable (such as Beretta M9), this is no big deal. But for out-of-print guns, magazines can be harder to source than the firearm, e.g., Norinco NS522 rifle magazines. Five NS522 magazines are worth more than one $500 NS522 rifle. So one learns to keep the magazines running. And those lessons can be used for other platforms. Since loading and unloading magazines causes the wear and the last round is a lot harder to load than the first, I tend to not top off magazines. For example, I often run G17 magazines with sixteen rounds as it is lot easier to seat the downloaded magazine when the pistol is in battery than one with a fully loaded magazine. That implies the downloaded magazine stresses the magazine spring and feed lips less than the fully loaded magazine does. That means my magazine should last longer.

On 1911 magazines, when the magazine starts to stop performing I replace the guts with Tripp Super 7 follower kits. Some of those magazine bodies have had at least five follower kits replaced over the years. I check and adjust feed lips id necessary when I do the follower kit work. I have learned that seven-round 1911 magazines are more reliable than eight-round ones (.45 ACP version, of course).

Of course this is what I do, and I am not an expert. I do hate to deadline stuff that can still be used, so that factors into my habits. Call me frugal or cheap.

Your understanding of how springs work is correct.

Springs wear due to developing micro cracks during cycles of expansion and contraction. Being in a static state, whether expanded or contracted does not wear springs. Leaving magazines loaded can expand feed lips but it doesn’t wear strings.

[blues]

While this thread is mostly retarded, I’ll say that I’ve both had and witnessed multiple instances of 30 round loaded USGIs AND PMAGs either not lock in on a bolt forward gun or get hung up trying to strip a round off the top.

I load all my 30 AR magazines with 28 rounds, and I download my Glock magazines by one round for the same reasons.
I’ve experienced it myself and seen it happen to numerous other people, both students on the line with me and students of mine.

You do you, though.

This is what I was referring to above, Jay. Unfortunately, I'm not sure if the issue was caused by me failing to properly seat the mag, or the bolt...which was subsequently determined by S&W to be out of spec.

Either way, it was enough to motivate me to download by two...in an abundance of caution.

[Jay Cunningham]

This is what I was referring to above, Jay. Unfortunately, I'm not sure if the issue was caused by me failing to properly seat the mag, or the bolt...which was subsequently determined by S&W to be out of spec.

Either way, it was enough to motivate me to download by two...in an abundance of caution.

I’ve seen it with all kinds of AR types. Colt all the way to DPMS.

[TGS]

As best I can tell, the practice of downloading mags came from the days of double-stack, single feed SMG mags that were ubiquitous up until WWII. With those you sometimes couldn't even load them to full capacity, and if you did it was known to cause problems as it was simply too much tension on the rounds.

Which is why we went to double-stack, double-feed magazines and haven't looked back.

The only purpose I see with downloading mags is if you have trouble seating mags on a bolt closed weapon. I typically haven't had trouble with this, but our FTU instructors advise people who do to download by 2 rounds. It usually shows up on the range, particularly with lower strength, small stature individuals. Otherwise we load our mags to full capacity, and with the exception of the previous mentioned demographic I never see it be a problem.

A "push-pull" when performing tac-reloads or administrative top-offs is the best way to prevent this from actually causing you a problem, IMO.

Re: 28 vs 30 in Aluminum GI mags- IME people from organizations where magazines are properly treated as consumables tend to fall into the 30 camp. Those who have trouble replacing mags and who have to destroy bad mags to keep them from being re-issued tend to fall into the 28 camp.

This all makes sense, especially the very last part.

When it comes to proper weapon maintenance/upkeep, the biggest detriment we have are former .mil. They bring a ton of atrocious, horrible, terrible habits from the plethora of old wives tales floating around in the military. Dumb motherfuckers that stretch their springs, treat mags as non-consumables, keep their Mk18s bone dry or very, very lightly lubed, inappropriately scrape the shit out of metal parts when cleaning because they're allergic to carbon and act the shit is kryptonite, etc.

They're also almost exclusively the people that have malfunctions and issues with their guns, but because they learned it in the military it's gods way and must be followed regardless of all the evidence to the contrary. FTU tries to train this stuff out of people and the weapons depot saw a dramatic decrease in broken guns once FTU started the push, but a lot of it falls squarely into the category of vampire herpes.

I learned the same thing in the same place.

Ditto.

[ST911]

Larry's 50/50 rule reminds me of Dean Caputo's MEAL acronym, magazines-extractor-ammunition-lubrication. Useful as both diagnostic and preventative process.