Loading 18 rounds in a 20 round magazine

[dahermit]

What was the basis for only 18 rounds in 20 round mags during early Vietnam War?

1. Anecdotes?
2. A sociological norm (seemly "good idea" accepted by most, A.K.A., "group think")?
3. Actual government (Army, Marines) data (tests of loading 18 vs. 20 rounds)?

If based on actual studies, is there a link to those studies.

 

[HWS]

That's news to me. I thought the argument was loading 28 in a 30 round magazine.

 

[44 AMP]

Can't point to anything official, or any studies, only that a lot of Vietnam vets state they were told not to load 20 in the 20rnd mags, to load 18 or 19.

PROBABLY began with some honest (if misplaced) concern about the "flimsy" aluminum magazines, something the Army had not had experience with before.

Or it could have been due to the fact that there's always some dummy (s) that can't or won't count and would overload the magazine, so by setting the limit short, it tended to avoid that.

Things in the service tend to get set by someone (and often at the NCO level) and follow on people keep doing it the same way.

Doesn't have to be right, just has to work.

 

[dahermit]

That's news to me. I thought the argument was loading 28 in a 30 round magazine.

"early Vietnam".
During the early years M16s were supplied with twenty-round magazines (and no forward assist).

 

[dahermit]

Can't point to anything official, or any studies, only that a lot of Vietnam vets state they were told not to load 20 in the 20rnd mags, to load 18 or 19.

PROBABLY began with some honest (if misplaced) concern about the "flimsy" aluminum magazines, something the Army had not had experience with before.

Or it could have been due to the fact that there's always some dummy (s) that can't or won't count and would overload the magazine, so by setting the limit short, it tended to avoid that.

Things in the service tend to get set by someone (and often at the NCO level) and follow on people keep doing it the same way.

Doesn't have to be right, just has to work.

In other words,
1. Anecdotes.
2. A sociological norm (seemly "good idea" accepted by most, A.K.A., "group think").

 

[north1]

The early mags were actually meant to be used once and thrown away. If loaded to full capacity the poorly made spring would loose tension and cause miss feeds. This was especially evident if they were loaded to capacity and not used for several days. Being under tension for that long would invariably lead to miss feeds. Have heard vets state this as well as read of this practice in first hand accounts. This coupled with the wrong powder used in rounds led to a lot of the first problems with the M16 early on in Vietnam. Having said all that I have not seen any government or private empirical studies done on this issue. Would be very interesting reading.

 

[dahermit]

...This was especially evident if they were loaded to capacity and not used for several days. Being under tension for that long would invariably lead to miss feeds.

That has been disputed. Current thinking is that the springs do not weaken under prolonged compression, but weaken via many cycles of compression and relaxation.

Also, early failures have been attributed to the feed lips spreading under prolonged tension causing misfeeds, not the springs failing.

That is why I was hoping for data via actual testing rather than anecdotes ("war stories").

 

[Jim Watson]

The idea goes back a long way, it was considered good practice not to cram the claimed 32 rounds into a Sten magazine.

ETA. Some BHP users like SAS loaded 12 for perceived greater reliability.

Chuck Taylor, on his way to 365000 rounds through a Glock 17, went to loading only 15 rounds because the magazines lasted longer.

 

[Shadow9mm]

Some schools reccomend only loading 29, I think warriors poet. Simply for ease of mag insertion on a closed bolt. Early mags had quality control issues. Springs, feed lips, followers. People did what they found to work. Not an issue these days

 

[jcj54]

The reasons behind practices...

In 1942 a doctor performing physicals at an induction center realized there were a fair number of otherwise healthy men being rejected because the guidelines required a minimum of two teeth on upper and lower gums directly opposed each other.
He asked the officer in charge why and was told the reason was unknown.
He became curious and after considerable effort found it dated to the Civil War when this was vital to bite the paper cartridges to tear them open....

 

[eflyguy]

Five apes in a cage..
https://jeffbridges.com/thewayitsalwaysbeendone

I worked in a high-tech industry where people just went on doing the same old thing over and over. I did a lot of public speaking and told this story often.

 

[north1]

I don’t think this is just “war stories”. Ask yourself. Why would a soldier short stack a clip when those 1 or 2 rounds over the course of a engagement could be the difference between life and death? IMHO the danger of miss feeds outweighed less ammo available. So there is a valid reason. I tend to believe someone in the trenches covered in mud and blood over a government study which might possibly have been done to produce false data to cover their rear ends. I guess that is just me. Perhaps a disinterested party has conducted such a study? Regardless. Would be a interesting read none the less.

 

[Rob228]

The closest I have come to figuring this out is that on the qual range it is insisted upon that you load with a closed bolt (insert a magazine on a closed bolt, rack, tap the forward assist, close the ejection port cover).

In higher levels of training all loading is done with the bolt locked to the rear.

Loading a full 30 round magazine or in the older case a full 20 round magazine into a closed bolt means it doesn't always seat, even though it may feel like it did. Also makes racking the bolt difficult because of the upward pressure.

 

[imashooter]

The early mags were actually meant to be used once and thrown away. If loaded to full capacity the poorly made spring would loose tension and cause miss feeds. This was especially evident if they were loaded to capacity and not used for several days. Being under tension for that long would invariably lead to miss feeds. Have heard vets state this as well as read of this practice in first hand accounts. This coupled with the wrong powder used in rounds led to a lot of the first problems with the M16 early on in Vietnam. Having said all that I have not seen any government or private empirical studies done on this issue. Would be very interesting reading.

News to me regarding disposable mags. We were instructed from boot, to AIT, in-country to load 18 in a 20 and 28 in a 30. 30s were rare. I still do to this day.

 

[zukiphile]

What was the basis for only 18 rounds in 20 round mags during early Vietnam War?

1. Anecdotes?
2. A sociological norm (seemly "good idea" accepted by most, A.K.A., "group think")?
3. Actual government (Army, Marines) data (tests of loading 18 vs. 20 rounds)?

If based on actual studies, is there a link to those studies.

Isn't this what happens when Magpul doesn't make parts for your rifle magazine?

In the mid 2000s, there was a service report on equipment problems. One topic was the magazines for Berettas. The dominant advice reported was to load only 10 rounds to avoid feed failures and an admonition that one should not remove the spring to stretch it and place it back in the magazine. An armourer I knew at the time said he told his people to stretch the spring even though it would mean an earlier failure. His logic was that a stretched spring that fails earlier is less likely to get someone killed because a broken spring just won't go out for use.

He described an institutional problem in which replacements for wear items weren't stocked.

 

[Rob228]

In the mid 2000s, there was a service report on equipment problems. One topic was the magazines for Berettas. The dominant advice reported was to load only 10 rounds to avoid feed failures and an admonition that one should not remove the spring to stretch it and place it back in the magazine. An armourer I knew at the time said he told his people to stretch the spring even though it would mean an earlier failure. His logic was that a stretched spring that fails earlier is less likely to get someone killed because a broken spring just won't go out for use.

Beretta magazines turned into a broken pez dispenser really quickly when sand combined with weak springs (in all fairness the springs had probably been in use for well over 20 years). The unit I was in at the time open purchased someone's spring kit (I think Wolff but it was way out of my pay grade in 2005). Seemed to solve the problems.

 

[eflyguy]

News to me regarding disposable mags. We were instructed from boot, to AIT, in-country to load 18 in a 20 and 28 in a 30. 30s were rare. I still do to this day.

My daughter went thru basic and AIT this year.

They loaded all magazines to capacity.

 

[jmr40]

It depends on the magazine. If you insert some fully loaded magazines, into some rifles, or handguns for that matter, with the bolt or slide closed you could easily create a malfunction when you try to chamber the 1st round. Some magazines, with some guns, simply won't fit in the gun when fully loaded and the bolt/slide closed.

You just have to know your gun and magazines. Some I load fully, some I download 1-2 rounds. If in doubt I'd say downloading by at least one round is prudent.

If you insert the magazine with the bolt/slide locked back and immediately chamber a round then it is less likely to cause a problem. Since it is commonly practiced in the military to have a loaded mag and empty chamber I can see why this was practiced.

Most of the newer mags seem to work better fully loaded. As a general rule, if you have to work hard to get the last 1-2 rounds into the mag it might be a good idea to stop on the last round that went in easily.

 

[Double Naught Spy]

Originally Posted by dahermit
What was the basis for only 18 rounds in 20 round mags during early Vietnam War?

1. Anecdotes?
2. A sociological norm (seemly "good idea" accepted by most, A.K.A., "group think")?
3. Actual government (Army, Marines) data (tests of loading 18 vs. 20 rounds)?

If based on actual studies, is there a link to those studies.

I think you forgot the category of experience.

Not all common knowledge ends up in studies or based on any sort of formal testing. When you get enough anecdotes from experiences together, they become a body of knowledge. "Group think," by definition, assumes no critical thinking on behalf of the participants. Vets found that they sometimes had trouble when loading mags to capacity by didn't have the same issues when downloading by 1 or 2 rounds. That information was shared. Some may have adopted it via group think, whereas others had to relearn the solution when they didn't practice it.

 

[dahermit]

I think you forgot the category of experience.

Not all common knowledge ends up in studies or based on any sort of formal testing. When you get enough anecdotes from experiences together, they become a body of knowledge. "Group think," by definition, assumes no critical thinking on behalf of the participants. Vets found that they sometimes had trouble when loading mags to capacity by didn't have the same issues when downloading by 1 or 2 rounds. That information was shared. Some may have adopted it via group think, whereas others had to relearn the solution when they didn't practice it.

"Common knowledge" should be suspect. For example, when I was a kid (many years ago), it was common knowledge that African elephants were never used in circuses because they were not trainable as are Asian elephants. Also, it was "common knowledge" that the reason Marco Polo's discovery of spices in China was so important is that due to no refrigeration, spices could be used to mask the smell of rotting meat so that it could still be eaten. Both "common knowledge" suppositions were in fact incorrect.

An example relative to firearms, was the "common knowledge" in the Garand era that it was a handy thing to clip a loaded M1 Garand loaded enbloc clip on the Garand's sling making for faster reloads. Also, the "common knowledge" (many suspect anecdotes about this one) that infantry men would carry an empty M1 clip to toss against their helmets to "trick" the enemy into thinking that the M1 was empty. In reality Col. Hackworth (author of "About Face"), told how he discovered as a young soldier in Korea, that clipping a loaded M1 clip on one's sling albeit looking cool, subjected it to filling with debris and mud when going prone. As for the empty clip trick, consider that not only would the enemy have to be very close, but with the report of an M1 at close range makes one's ears ring and preventing the hearing of that relatively faint "ping" that the clip makes when ejected, very unlikely to be of any advantage. Yes, many anecdotes, but many of the just B.S.