The "magical" 17 rounds...


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Skribs
July 23, 2012, 03:04 PM
Looking at most 9mm double-stack "full"-size handguns, I notice the majority of them have 15-17 round capacities, most of them right at 17 rounds. There are only 3 that I know of that have more - the Para double-stack 1911 in 9mm (P18-9 or something like that), the Caracal, and the XDm.

What is so special about these three, that don't seem to be much bigger at all than the 17-round conglomerate, that they have 18 (or even 19) rounds?

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rcmodel
July 23, 2012, 03:18 PM
Hmmm?

Just off the top of my head, it is because the mags have steel body's.

The Glock and others use plastic with a steel liner for stiffness.

And they are thicker walled, so take up more room which could have been used for cartridges in a thinner wall steel mag.

But thats just a WAG.

An interesting point is the Browning P35 High-Power only had a 13 round capacity.
That was done so the magazines could be left loaded indefinitely with no risk of over-compression weakening the spring.

The same cannot be said of the 17 & higher capacity mags that use over-compressed springs.

rc

Skribs
July 23, 2012, 03:27 PM
It's just always seemed so arbitrary. I'm a bit OCD, I like multiples of 5. A prime number as the "standard" just seems very weird.

JTQ
July 23, 2012, 03:35 PM
It is an evolution.

The Hi-Power was, for the most part, the capacity king for many years at 13 rounds. Then came the Beretta 92 and everybody made guns with mags with 15 rounds. Next was the Glock 17 and 17 became the number. You could put more rounds in, but at some point the grip becomes impractically long.

The CZ SP-01 comes standard with an 18 round mag, by the way.

http://www.cz-usa.com/products/view/cz-75-sp-01/

2wheels
July 23, 2012, 03:39 PM
It is an evolution.

The Hi-Power was, for the most part, the capacity king for many years at 13 rounds. Then came the Beretta 92 and everybody made guns with mags with 15 rounds. Next was the Glock 17 and 17 became the number. You could put more rounds in, but at some point the grip becomes impractically long.

The CZ SP-01 comes standard with an 18 round mag, by the way.

http://www.cz-usa.com/products/view/cz-75-sp-01/
Kinda reminds me of the horsepower wars with car manufacturers. Bigger numbers are a selling point, even if it isn't a significant difference.

It is funny sometimes to see people worry about 1 or 2 rounds, when they're already in the double digits.

Skribs
July 23, 2012, 03:50 PM
It is funny sometimes to see people worry about 1 or 2 rounds, when they're already in the double digits.

That "one more" might always be the one you need.

So, we went from 13, to 15, to 17...we've had a 19 on the market for a while now. Why aren't more people making a 19?

ATLDave
July 23, 2012, 03:56 PM
There are extended buttplates for most popular, modern handguns. These add 2-7 rounds (usually 2-3 in bigger calibers, 3-5 in 9mm) using the existing mag body. So if you want 19 9mm's, just go buy an extended 'plate, and don't load it full. ;)

For pistols often used in competition classes without a 10-round limit, one can usually find followers that allow an extra round or two; often, these followers are finicky about what ammo they'll reliable feed to the gun. You give up a little anti-tilt stability when you make the follower shorter...

There are also a few "double-stack" mags that aren't quite double-stack. My old Browning BDM mags, for instance, are slimmer than most other double-stack mags (to fit in the slimmest hi-cap grip I've ever seen), but they top out at 15.

ATLDave
July 23, 2012, 03:58 PM
Just off the top of my head, it is because the mags have steel body's.

The Glock and others use plastic with a steel liner for stiffness.

And they are thicker walled, so take up more room which could have been used for cartridges in a thinner wall steel mag.

My M&P9, which holds 17, uses steel-bodied mags.

I suspect that the overall mag length (and, therefore, grip length) of the 18- and 19- round designs is just greater. Hell, you can make a 30-round pistol magazine, as long as you're OK with the length; Glock sells them.

Skribs
July 23, 2012, 04:05 PM
http://the-m-factor.com/html/specs_2.html
http://www.smith-wesson.com/webapp/wcs/stores/servlet/Product4_750001_750051_765668_-1_757954_757781_757781_ProductDisplayErrorView_Y

The M&P is 5.5", XDm 5.6" tall. You can't fit a 9mm round into a 0.1" difference.

Devonai
July 23, 2012, 04:24 PM
I have watched the growing capacities with interest, mostly as it pertains to my Beretta 92FS. I've gone from carrying 2x15 and 2x10 when I was too poor to afford more pre-ban mags, to trying the 17-rounders out, to the latest 18 and 20-round Mec-Gars. All functioned fine, but by the time you've got a 92FS with 20+1 on board, it is awfully heavy.

rcmodel
July 23, 2012, 04:33 PM
Unless you are drowning or on fire.

rc

armoredman
July 23, 2012, 04:43 PM
http://i16.photobucket.com/albums/b13/armoredman/CZ%20posters/CZbook4.jpg

The SP-01 mags DO hold 18, and some hold 19, but that's with a built in grip extension. The SP-01 also can use the CZ 75 standard 16 round mags, which I use in summertime for more concealability.

http://i16.photobucket.com/albums/b13/armoredman/CZ%20posters/Phantomwith16roundmag2.jpg

I like having options, and more ammo gives more options. I think 15-18 is about right for a 9mm auto, as too much more adds more weight than needed. Perhaps the FiveseveN got it right - what is that, 20/30 rounds in a single magazine?:scrutiny:

2wheels
July 23, 2012, 04:46 PM
That "one more" might always be the one you need.

So, we went from 13, to 15, to 17...we've had a 19 on the market for a while now. Why aren't more people making a 19?
That's certainly true, but when is enough enough? You've got to draw the line somewhere, or you end up walking around with a 33 rounder sticking out of your Glock. Conceal that :D

I imagine there are a few reasons that you don't see everyone coming out with 19+ round mags. Just shooting in the dark, I would say to fit one or two more rounds into some of these guns without extending the mag (or worse, making the grip longer/wider), they've got to redesign the mag/spring/follower, that may or may not cause reliability or mag spring life issues. I don't know, maybe they just don't figure that it's worth the effort with their current designs so they just let the aftermarket guys like MecGar deal with the problem if people want an extra bullet or two.

I don't even know what Springfield had to do to squeeze 19 rounds into a gun only 0.1" taller than the M&P, so I don't know what it would take for other companies to do the same.

Skribs
July 23, 2012, 04:47 PM
Yeah if they ever do a .30 caliber straight-walled service cartridge I'm guessing they'll have 21-23 rounds in that thing.

MachIVshooter
July 24, 2012, 12:49 AM
There are only 3 that I know of that have more - the Para double-stack 1911 in 9mm (P18-9 or something like that), the Caracal, and the XDm.

The full size Tanfolgios built on the large frame (since 2007, IIRC) hold 18 rounds in 9x19mm, 9x21mm and .38 Super.

Warp
July 24, 2012, 12:58 AM
Hmmm?

Just off the top of my head, it is because the mags have steel body's.

The Glock and others use plastic with a steel liner for stiffness.

And they are thicker walled, so take up more room which could have been used for cartridges in a thinner wall steel mag.

But thats just a WAG.

An interesting point is the Browning P35 High-Power only had a 13 round capacity.
That was done so the magazines could be left loaded indefinitely with no risk of over-compression weakening the spring.

The same cannot be said of the 17 & higher capacity mags that use over-compressed springs.

rc

What constitutes an over-compressed spring? How is it determined? Who do you believe uses an 'over-compressed spring'?

beatledog7
July 24, 2012, 06:44 AM
The magazine capacity race is at least in part about appeasing the machismo of potential buyers. Some buyers want to take their nearly-20-round mags to the range and be able to say, "Mine's bigger than yours."

For the gun buyer who's more focused on the practical aspects of magazine capacity, there is no denying that having more rounds--as long as you can count on them to cycle--gives more options. But there must be a practical limit after which mechanisms suffer reduced reliability.

C0untZer0
July 24, 2012, 07:13 AM
I'm always amazed at how ga-ga people get over at Glocktalk when the 33rd mags go on sale...

A 33rd magazine sticking out of the bottom of my Glock...

Really ???

mes228
July 24, 2012, 07:30 AM
I carry a Glock 23 .40 caliber stoked with Glock 22 mags. You can purchase a plastic collar to fill the slight gap between the end of the mag and the grip. This gives you a 16 round .40 caliber in the size of the compact Glock 19 in 9mm. I think this combo is pretty much tops for size, round capacity, reliability, ease of carry, cost, re-sale value, ease of maintenance, durability, cost & availability of magazines, etc. etc. And any other parameters you can think of. The cost and availability of magazines is a HUGE plus. You can purchase one of the best mags in the world for 1/2 to 1/3 the price of many other manufactures. Can't have too many mags. Just my opinion. Your mileage may vary.

highorder
July 24, 2012, 07:30 AM
...by the time you've got a 92FS with 20+1 on board, it is awfully heavy.

I'm with you there. My M&P9 at 17+1 is quite heavy.

I've considered down loading mags on the occasions I carry it, but that's a whole philosophical can o' worms.

mes228
July 24, 2012, 07:55 AM
Yes, I agree the ammo weight is heavy in the high capacity pistols. I feel it's lighter and at least equal to two 1911's with 7 round mags. Here is a hint on how to carry a slightly heavy pistol. Google "Hidden Tailor belt" - it a rubber belt that has little "knobs/tits". It's designed for Police, Referees, etc. ie anyone doing vigorous activities that wishes to keep their shirt tucked in. The rubber knobs grip the shirt and the "grippyness" of the rubber grips the pants and you can pretty much wrestle alligators and your shirt will stay tucked in.

The "Hidden Tailor belt" has a great advantage, in my opinion and experience, for concealed carry. It helps hold your pants, shirt, AND PISTOL "UP". I wear one every day and have for years. Even though in the summer I wear a loose shirt that is un-tucked. The Hidden Tailor grips my tee shirt and pants and helps support the pistol. In the winter I do tuck my shirt and wear a vest to cover the pistol. I'd be lost without my Hidden Tailor belt. Just my opinion and "your mileage may vary".

Edited: I corrected the orientation of the Hidden Tailor Belt. Works much better if the knobs/tits are toward the shirt. Flat side toward the pants. The HT Belt is a great, simple invention.

Urban_Redneck
July 24, 2012, 09:07 AM
Another factor in mag capacity is how gradual or abruptly the mag tapers at the proximal (feed) end. Caracal has a quite short taper.

NG VI
July 24, 2012, 09:28 AM
It's a geometry and design thing, human hands tend to fit a certain range of sizes, and pistols tend to be designed with a certain range of grip lengths and widths, and 9mm cartridges aren't particularly large, so it's very easy to fit fifteen rounds into a grip that isn't all that long or wide, and if you have a full size gun that wasn't designed to have a super slim grip, most of them quite easily have space for more than fifteen rounds.

Nobody is really designing pistols strictly for a set number of rounds, it's a byproduct of the design process. A rifle or other type of gun that generally loads elsewhere than the grip will have magazines designed for a specific number of rounds, but for a pistol the grip size and construction of the pistol and magazine determine capacity for the most part.

Certaindeaf
July 24, 2012, 09:34 AM
Yes, I agree the ammo weight is heavy in the high capacity pistols. I feel it's lighter and at least equal to two 1911's with 7 round mags. Here is a hint on how to carry a slightly heavy pistol. Google "Hidden Tailor belt" - it a rubber belt that has little "knobs/tits". It's designed for Police, Referees, etc. ie anyone doing vigorous activities that wishes to keep their shirt tucked in. The rubber knobs grip the pants and the "grippyness" of the rubber grips the shirt and you can pretty much wrestle alligators and your shirt will stay tucked in.

The "Hidden Tailor belt" has a great advantage, in my opinion and experience, for concealed carry. It helps hold your pants, shirt, AND PISTOL "UP". I wear one every day and have for years. Even though in the summer I wear a loose shirt that is un-tucked. The Hidden Tailor grips my tee shirt and pants and helps support the pistol. In the winter I do tuck my shirt and wear a vest to cover the pistol. I'd be lost without my Hidden Tailor belt. Just my opinion and "your mileage may vary".
Huh, never heard of such a thing.. cool.
Maybe you could mention this over at "holsters and gear" here so more know about it.. anyway.

VBVAGUY
July 24, 2012, 10:50 AM
My Sig P229 holds 18+1 rounds with the Mec-Gar magazine.
My Springfield Armory XD9 service normally holds 16+1 with the stock magazine, but with the Mec-Gar magazine holds 18+1.
I hope this helps. God Bless :)

Skribs
July 24, 2012, 10:52 AM
Those extended magazines aren't really part of the topic here. Any double-stack can have an extended magazine that will hold any number of rounds.

Devonai
July 24, 2012, 12:00 PM
I see it as sort of a chicken-and egg issue. My guess is that most pistols designs are finalized before the engineers figure out how many rounds they can shove into a mag that can subsequently fit into the mag well they've created.

Or, perhaps the pistol is designed around a particular capacity. If the marketing department says, "this pistol must have at least a 17 round mag," then the pistol would be designed around the mag to some extent.

Just spitballing here.

sKunkT
July 24, 2012, 12:03 PM
I also can squeeze in 2 more rounds with a flush fitting aftermarket mag (over a factory 15 rounder) in my Ruger P95DC. It is interesting what the different designs can do with the same amount of space. I was considering buying another newer 9mm with more capacity, since my P95 came with 10 round mags. I saved myself a few hundred dollars when I realized it could hold 17 round mags without an extended mag. Sweet.

scramasax
July 24, 2012, 12:34 PM
Shooting more than a string of 10 at the range and My accuracy suffers. For a carry gun I have no problem with having five shots on tap. I don't expect to be repelling the "hordes" before I can get to a bigger gun. The grip size and shape is more important to me than the maximum amount of ammo on board. You can't miss fast enough. The capacity wars have more to do with marketing than reality.

Jmhu, Cheers,

ts

Warp
July 24, 2012, 12:38 PM
Shooting more than a string of 10 at the range and My accuracy suffers. For a carry gun I have no problem with having five shots on tap. I don't expect to be repelling the "hordes" before I can get to a bigger gun. The grip size and shape is more important to me than the maximum amount of ammo on board. You can't miss fast enough. The capacity wars have more to do with marketing than reality.

Jmhu, Cheers,

ts

When carrying, how will you get to a bigger gun?

Skribs
July 24, 2012, 12:46 PM
Shooting more than a string of 10 at the range and My accuracy suffers. For a carry gun I have no problem with having five shots on tap. I don't expect to be repelling the "hordes" before I can get to a bigger gun. The grip size and shape is more important to me than the maximum amount of ammo on board. You can't miss fast enough. The capacity wars have more to do with marketing than reality.

There was a thread in the Handguns: General section recently which showed how likely you are to get 2 solid hits on target with 30% accuracy (accuracy stats taken from real shootings by NY cops), and with only 1 assailant, 5 shots was likely to yield 2 hits only 47% of the time. That's on a single assailant, not a "horde".

http://www.thehighroad.org/showthread.php?t=665883

Orion8472
July 24, 2012, 12:49 PM
The 18 + 1 capacity of the CZ SP-01 was one of the selling point for the gun for me. . . . . . . as was the 20 + 1 for the FNH Five Seven pistol. Of course, neither of those are very good for conceal carry. As I see it, the best one for capacity and carry ability would be a Glock 19.

armoredman
July 24, 2012, 10:33 PM
Orion, I conceal an SP-01 every day. :) Good holster and good belt will do it.

balance 740
July 25, 2012, 06:46 AM
What constitutes an over-compressed spring? How is it determined? Who do you believe uses an 'over-compressed spring'?

There were reports of mag springs failing on FN's FNX-9 pistols simply by leaving the mags loaded and inserted in the pistol for a period of a few weeks. I'm not sure if this has been resolved as of yet, as I sold my FNX a little while back.

http://fnforum.net/forums/fn-fnx/14984-magazine-issue.html

I also remember a Chuck Taylor Glock torture test, where he stated that his Glock 17 mags would last much longer when he loaded them to just 15 rounds rather than 17. I believe Glock has redesigned their mags since then.

http://www.tactical-life.com/online/combat-handguns/glock-17-9mm-torture-test/

During this initial phase, I also wore out several sets of magazines, noting that the follower springs tended to get soft after a month or so if the magazines were left fully loaded with 17 rounds. As a result, after replacing the springs, I decided to experiment a bit, loading them with only 15 rounds instead of the usual 17.

Within a short period of time, it became obvious that the remedy worked. The magazines functioned perfectly even after extended time periods when so loaded. In fact, though they’re the old type that didn’t drop freely from the weapon, I still have four of them and even after thousands and thousands of rounds, and they still work reliably.

Other companies like H&K seem to be going the other direction and seem to be putting less rounds in their mags when compared to mags of similar size from other manufacturers.

An H&K USPc has about the same grip length (if not longer) as a Glock 19, though the Glock holds 2 more rounds.

An H&K P30 has about the same grip length (if not longer) as a Glock 17, though the Glock holds 2 more rounds.

I've heard that this was to increase reliability and spring life.

Scottzilla
July 25, 2012, 08:39 AM
I think from a historical perspective, 17 rounds became desirable for service pistols (Ie; police departments).
I read that NATO chose the 5.7 as their new service pistol because they were able to stuff 30 rounds in a mag so that does indicate 17 is about the max the mfg's feel comfortable stuffing into a pistol.

JohnBT
July 25, 2012, 08:58 AM
I think 15+1 is magical. Of course it's heavy and an FNP-45 USG.

Certaindeaf
July 25, 2012, 10:13 AM
18 total or so probably became a/the magic number because back in the old revolver days, that's what cops carried on duty.. six in the cylinder with two loaded speedloaders on the belt. So then of course it was logical and way more better and or an easy sell to go the way things have gone.. to carry two extra loaded mags.. everyone was and is happier?

GLOOB
July 26, 2012, 04:18 PM
An interesting point is the Browning P35 High-Power only had a 13 round capacity.
That was done so the magazines could be left loaded indefinitely with no risk of over-compression weakening the spring.
The Hi Power mags were notorious for crapping out when filled to capacity. The British military loaded their Hi Powers with 12 rounds, which they learned from experience. Perhaps the springs are better these days. As others have noted, reliable 17 rd mags can be had for the M9, which originally held only 15.

The number 17 isn't magic. It's just the approximate number that fits in a full size grip.

Certaindeaf
July 26, 2012, 04:21 PM
The Hi Power was notorious for jamming when filled to capacity..
Never heard that one nor has that been my personal experience. Mags stuffed and cocked for almost 35 years.

GLOOB
July 26, 2012, 04:35 PM
I don't have firsthand knowledge, but it's something I've seen cited by several sources who claim to have served. Forgive me if it's wrong, but I've read it so many times, I thought it was not only factual, but in the realm of common knowledge.

Again, perhaps the springs weren't as good back then. Or maybe they downloaded to avoid replacing old mag springs when needed.

Certaindeaf
July 26, 2012, 04:37 PM
It well could have been superstition.. I've actually seen, first-hand, some odd stuff.

Dr.Rob
July 26, 2012, 05:51 PM
Sometimes enough is enough. While Ramline 15 rd magazines work great in my HP clone.. not a single KRD 17 shot mag has ever worked. Sticky followers, followers that jump spilling handfuls of bullets.. just not worth it. Beware aftermarket + capacity magazines.

17 is the 'magic number' because that's how many 9mm's a Glock 17 holds.

Warp
July 27, 2012, 12:04 AM
Hmmm?

Just off the top of my head, it is because the mags have steel body's.

The Glock and others use plastic with a steel liner for stiffness.

And they are thicker walled, so take up more room which could have been used for cartridges in a thinner wall steel mag.

But thats just a WAG.

An interesting point is the Browning P35 High-Power only had a 13 round capacity.
That was done so the magazines could be left loaded indefinitely with no risk of over-compression weakening the spring.

The same cannot be said of the 17 & higher capacity mags that use over-compressed springs.

rc

What constitutes an over-compressed spring?

What are some example guns/magazines that you believe use an over-compressed spring?

rcmodel
July 27, 2012, 12:20 PM
I mentioned Glock as one.

Even the Glock annual published by Glock every year had an ongoing "torture test" by a fellow named Chuck Taylor who said mags fully loaded with 17 rounds had weak springs that would not operate the slide stop after about 5,000 rounds.

He went on to say that mag spring life could be increased dramatically, or almost indefinitely by downloading by 2 rounds.

That has been my experience with a Glock 23 I have owned for going on 17 years.
All my mags still have the original springs in them and are still going, and going, and going.

As for what other guns?
I really don't have an answer to that, as I have no experience with every new hi-cap gun that has come out over the last several years.

But my feeling is probably all of them that hold half a box of ammo would benefit from downloading a couple rounds.

rc

Warp
July 27, 2012, 12:49 PM
Interesting. 5,000 rounds through one single magazine is a metric crapload. I personally would MUCH rather have the full capacity and simply change out the mag spring when the slide stop doesn't get activated after putting 5,000 rounds through the one mag.

I wouldn't call that over compressed, either. 5,000 rounds on one single mag/spring is more than plenty

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