what is "the right" capacity for a given pistol and how do manufacturers choose it?

[riffraff]

This is something that's probably been covered here before but I just want to bring it up for people to weigh in.. Educate me please.

There are some simple real estate considerations, ie you want a smallish carry pistol in .45 it's not going to hold 15 or likely even 8 rounds.. Sure I get that. You want a slimmer handle so the only option is a single stack - makes perfect sense. But what about when there is no such limitation but they do it anyway?

I see some mainstream manufacturers, who supply governments that analyze all this stuff to death, who offer lots of capacity, others who are conservative with it (say Glock & Sig respectively).. For instance why does Sig only offer an 8 round mag for their P220 in 10mm, yet offers a 10 round mag for the (smaller) p220 in .45 ? Glock offers what a 15 round (assume a double stack), maybe more in 10mm for some models?

Is it because the absolute most reliable function is attained with a smaller single stack and it's a balance of capacity versus reliability? Or weight? Or some other consideration for how many rounds you can actually pump out accurately in a timeframe given the recoil?

Even with say .22LR, I read things like "well .22LR only functions reliably in magazines of 10 or less" and you got a whole bunch of manufacturers offering 10 round mags and that's it for such pistols, yet we seem to be able to put 25, 30, 40, whatever in a rifle mag and they run great, a pistol here and there or mag hacks exist in .22LR carrying 15, 17, 20+ rounds and they run great. Most of our .22LR pistols could easily fit a 15+ round mag, but it's only the fringe brands who offer that sort of thing out of the box. Why is that? How do they choose this stuff?

It's come to mind a bunch weighing different models I'm interested in, but recently was kinda disappointed when I found the huge 10mm Sig P220 was only going to hold 8 rounds, no other options, while my .45 version holds 8 in a standard form and 10 w/ the extendo (which admittedly is kinda stupid but they should be able to offer a 10 round mag for the 10mm version and likely they could fit a standard mag of 9 rounds in there).

[44 AMP]

Being neither a firearms manufacturer nor a mind reader I can't say with certainty what they are thinking, but I can offer some ideas about some of the things that get considered.

The first thought is not to confuse the "standard" mag capacity with extended mag capacity. Like that Sig P220 you mentioned. Standard mags in .45 hold 8. If a maker offers an extended mag, its because there is a demand for it, or they anticipate one. If there isn't they don't. That's basic economics.

Is it because the absolute most reliable function is attained with a smaller single stack and it's a balance of capacity versus reliability?

This can be part of it. Remember that there is only so much space available in a standard magazine, and part of that space is used by the spring.

There is a balancing act with the spring, as well. It has to be strong enough to lift the entire stack of round IN TIME for the slide to feed the top round. Recoil drives the rounds down, and different rounds have different amounts of recoil. PLUS if the spring is "too" strong it makes loading the magazine difficult and that turns people off, which reduces the popularity (and sales) of your pistol.

Rounds like the .22LR have their own special needs, being both quite long for their diameter and rimmed. 9 or 10 is all that will fit in a single stack box magazine that still fits in the regular size pistol grip.

Additionally, those pistols like the Ruger Mk series, and others are design philosophies carried over from the time when firepower (mag capacity) was not the big selling point of .22LR pistols. The buying public simply wasn't asking for more rounds capacity the way they do today.

Again, tis economics, and its going to take more than a bit of demand for makers to redesign or make new guns double stack in .22LR. Some are doing that, some have done it to use the Ruger design rifle mags.

There are other factors at work, as well. The makers want to sell their pistols to as many people in as many places as possible. Sadly, many places now have limits on acceptable magazine capacity.

These are just a few things off the top of my head, I'm sure there are others I haven't thought of, but it gives some idea I think.

[Forte S+W]

As near as I can figure, it all stems from a lack of innovation or experimentation.

The firearms market tends to play it safe and stick with what works, so many just copy whatever works, is popular, and thus will be profitable, hence why every year there are more boring polymer framed, striker fired 9mm pistols, even from manufacturers who have already released something of the like in recent years.

Innovation requires a substantial financial investment to cover the expenses of research and development, yet isn't guaranteed to pan out nor yield a profitable product, ergo most firearms manufacturers prefer to copy proven designs rather than attempt to design something new from the ground up or otherwise make extensive modifications to existing designs.

So when there are many .22 Pistols with 10 round magazines on the market which are plenty profitable, there's little reason for anyone to attempt to design reliable 15+ round magazines, much less a whole new pistol which can feed from said magazines. And yes, it most likely would be costly to design higher capacity .22LR magazines in particular which could overcome the persistent issue that is rimlock.

[Areoflyer09]

Given that most people are content with 10rds in 22 pistols and that satisfies states capacity limits, why build multiple magazines if you don’t need to? What are you gaining? Will the free states buy enough of the increased mag to make the changes profitable?

There are some options out there that have higher capacity. The Taurus TX22 holds 16 and seems to be doing well without any major issues from the magazine. The Kel-Tec CP33 holds 33 rounds, but is subject to rim lock unless loaded exactly as the instructions say.


For centerfire, I’d imagine it’s mostly due to size constraints. Though there are probably just some oddballs out there, with some reason for their decisions that isn’t plainly obvious.

Take the Glock 19, where do you make a change to increase the capacity? Mag length is about the only place, which is admittedly how most pistols have increased capacity. We have seen some innovations in capacity with the 1.5 stack mags, like the P365 uses.

[TXAZ]

Originally Posted by riffraff

...
It's come to mind a bunch weighing different models I'm interested in, but recently was kinda disappointed when I found the huge 10mm Sig P220 was only going to hold 8 rounds, no other options, while my .45 version holds 8 in a standard form and 10 w/ the extendo (which admittedly is kinda stupid but they should be able to offer a 10 round mag for the 10mm version and likely they could fit a standard mag of 9 rounds in there).

It might be that the 10mm Sig isn't able to fit in the hand of 75% of all shooters.

I have a Desert Eagle in .44 Mag (single stack), and very few people can wrap 1 hand fully around the grip comfortably and feel secure in their grip. My guess is many / most double stack 10mm's (and 45's) don't give most shooters the confidence in hanging on to the weapon with 1 hand while rapidly dumping the magazine into the target.

[Nathan]

Grip size, profitability, experience of design team with certain parameters.


Edit....and now days, regulation must play a role.

[Lavan]

TEN ROUNDS !!!

The State of California has researched the issue and found that 10 rounds can not hurt anyone or anything.
So, to avoid liability issues, manufacturers should always go with 10 rounds.

For peace and harmony.

[Carl the Floor Walker]

I have no problem with 10 rd magazine. Do care what California or any other state say's as well. KISS

[rock185]

"The right" capacity is whatever a manufacturer thinks will sell, and return a profit.

[T. O'Heir]

There is no "right capacity". However, in most cases the length of the magazine, without sticking out the bottom, determines capacity. Silly laws notwithstanding.
Then you get into the assorted shooting games that can create a demand for larger capacity mags.
10 rounds in .22 pistols is usually about target shooting. 10 rounds slow, 10 rounds timed and 10 rapid.

[Jim Watson]

Like that Sig P220 you mentioned. Standard mags in .45 hold 8.

The original P220 .45 magazine held 7, just like the 1911.
The original original P220 was the Swiss P75 9 round 9mm; like Colt .38 Super.

The first pass at 8x.45 was just a shallow follower and a heavily compressed spring. The current crop of 1911s gains a little space by a protrusion disguised as a base pad. I don't have a P220 8 shot.

[RickB]

I've always favored guns that had "power" proportional to their size.
So, a 9mm 1911 is a no-go; I have a compact 9 that is literally half the size and weight, and is down only one round of capacity.
A full-size 9mm that holds 15 rounds is good, because the extra size/weight is used to increase capacity.
I used to carry a 6-shot, 34oz .45, but now it's either a smaller/lighter gun, or a higher-capacity gun.

A lightweight .45 or 10mm that holds eight or nine rounds is also a good thing, but integrating a higher-cap mag into a plastic frame is probably going to please more people.

Manufacturers are going to try to please everyone. I handled a buddy's Witness Stock II, which is available in 10mm, with high capacity, and it is a beautiful gun, if you don't want the modern "implement" style.

[riffraff]

This is good stuff guys, thanks for weighing in. What I think Im learning is there isn't a real theory on this stuff. Its probably more about real estate and percieved marketability than anything.

As far as what I question, it's more when a manufacturer could but they don't, like the 10mm example being smaller than .45 and likely there being enough room in the handle for an extra round but they pass on it. I figured there must be a good reason, like a military or law enforcement specification even maybe.

On most guns though I'd say within reason there is a market for extended mags, seems like most immediately go hunting around for a little extra capacity after any purchase. Take an SR22 for example, lots of us go and spend the $$ and effort to add 2 kits to our mags to bump them up to 17 rounds from 10, yet Ruger seems to take no notice and instead invests in color schemes and threaded barrel options .

[44 AMP]

The original P220 .45 magazine held 7, just like the 1911.

You're right, my bad, the gun held 8, the mags held 7.

[JDBerg]

My Glock 21 takes 13 round magazines and most folks would say that the grip on this gun resembles a 2x4 but with my big hands it works just fine for me.

The .45 GAP was & really still is the answer to making the .45 ACP case more compact, considering the improvements in powder technology, the case holding the 45 caliber bullet can be significantly shorter, and a Glock 38 having a Glock 19 form factor with an 8 round magazine is a viable option for a CCW. The round was designed by CCI Speer, and you can get factory Gold Dots in this caliber. Although these ain’t cheap & can be somewhat hard to find, these sure do work for the intended purpose of a CCW.

[jmr40]

Glock offers what a 15 round (assume a double stack), maybe more in 10mm for some models?

The Glock 20, in 10mm came 1st. It was designed to work with 15 round magazines. The Glock 21 in 45 ACP came after the 10mm and is built on the same size frame. 13 rounds of 45 is as many as they can fit in the same size magazine.

For years the standard for 9mm has been 15 rounds. After Glock came out with the G17 that held 17 rounds most manufacturers have been forced to find a way to fit 17 rounds into similar size guns to take away that Glock advantage.

The 1994-2004 AWB had a big influence on handgun design. With a 10 round limit it didn't make sense to own a gun designed to hold 13, 15, or 17 rounds. This is a big reason why the 40 S&W came to dominate during that time. A G23 held 13 rounds traditionally and a G19 held 15 rounds. If most people were going to be limited to 10 rounds anyway most of them opted to go with a larger caliber in the same size gun. Had it not been for the AWB I have my doubts that 40 S&W would have become so dominate. It took a few years, but since the ban has expired the 9mm has slowly pushed the 40S&W aside.

During the AWB there were numerous much smaller guns designed specifically to meet the 10 round limit. Even today with many states staying with the 10 round limit there are still many guns sold nation wide that were designed specifically to meet those states laws.

[Forte S+W]

Originally Posted by jmr40

The 1994-2004 AWB had a big influence on handgun design. With a 10 round limit it didn't make sense to own a gun designed to hold 13, 15, or 17 rounds. This is a big reason why the 40 S&W came to dominate during that time. A G23 held 13 rounds traditionally and a G19 held 15 rounds. If most people were going to be limited to 10 rounds anyway most of them opted to go with a larger caliber in the same size gun. Had it not been for the AWB I have my doubts that 40 S&W would have become so dominate. It took a few years, but since the ban has expired the 9mm has slowly pushed the 40S&W aside.

I'm going to have to disagree with you there. If anything, the popularity of .40 S&W was due to its adoption by Law Enforcement agencies across the United States. I'm sure that the AWB certainly helped its popularity, but if it were the main reason then its popularity would have plummeted promptly in 2004 when the AWB ended. The .40 S&W remained popular right up until the FBI dropped it and police began following suit, over a decade after the AWB ended.

Honestly, how many times have you seen this statement made in gun forums online? "If it's good enough for [insert authority here] it's good enough for me."

Many Second Amendment supporters aren't really Firearms Enthusiasts, they're just people who carry firearms for self-defense, and thus many of them base their decisions of what they will carry based on whether the police are carrying rather than devote time researching firearms/cartridges in order to find the best option for themselves.

If the .40 S&W was popular for any peripheral reason aside from its own merits, then it's because police carried it, not because of the AWB.

[Nathan]

Grip size - This one is pretty simple. You determine your max length, width, circumference and then your material of choices min thickness. Then you determine which oal you will fit....9/40 vs 45/10mm. Width becomes the driving factor. You can go from single stack to the max width before the rounds exert so much side to side force that they jam up in the mag. Wider is higher capacity, but worse for feeding. Glock is about the widest.....

profitability - Manufacturers are always looking for common magazine bodies, common frames, etc. This is why 40’s usually have wide variation......because manufacturers are trying to use common frames and common mag bodies with tweaks to the exclusive parts.

experience of design team with certain parameters - Making a design different than your last one drives design cost up because you will have to add more testing....and likely have warranty issues.

regulations - Do you make a 17rd mag, downsized to 10 and 7 rounds or 3 different sized guns that maximize the potential of of each regulated size? That goes back to profitability....can I even sell enough guns to payoff the tooling and development in New York where they are working to ban all guns every hour!

[stinkeypete]

^^^ grip size plus marketing.
Let’s face it, one of Glock’s other genius moves was marketing itself in to the provider for a firearms arms race so people with perfectly functional handguns were convinced they needed to upgrade.

I’d be perfectly happy to purchase an old Gen 1 Glock 19 at a bargain price. Nothing wrong with it. But then again I would also purchase and old S&W model 19 at a bargain price. Nothing wrong with that one, either. But then I would also purchase an old Walther in .380 and my beloved Bersa Thunder is close enough a clone. I sold my .40 cal Glock because it was just too loud and snappy and my big bore sixgun is much better for deer hunting.

The latest fad seems to be single stack Glocks because they are not bulky, mid size .380’s and little pocket .380s. If they can sell ‘em, little pocket .25s will probably come back.

Why this evolution? It’s a tough business when a product sold in 1955, with reasonable care, is still functioning perfectly in 2020. How are you going to sell more without creating a demand or trying to convince people that “planned obsolescence” is perfectly fine for equipment your life might depend on?

Functionally, the product has to be small, light weight, reliable, ergonomic, and have enough rounds so people will THINK it has enough rounds to “get the job done.”

In a recent tragedy, we saw that one round was enough to stop a maniac in a Texas church. 100 rounds are not enough if they all miss.

Marketing. A nicer way to say it is “giving people choices.” A meaner way to say it is “some people will buy any darned thing based on advertising and sales.”

[Lavan]

Don't know why I post. I customarily only load 5 at the range.

[zukiphile]

Originally Posted by Riffraff

Even with say .22LR, I read things like "well .22LR only functions reliably in magazines of 10 or less" and you got a whole bunch of manufacturers offering 10 round mags and that's it for such pistols, yet we seem to be able to put 25, 30, 40, whatever in a rifle mag and they run great, a pistol here and there or mag hacks exist in .22LR carrying 15, 17, 20+ rounds and they run great. Most of our .22LR pistols could easily fit a 15+ round mag, but it's only the fringe brands who offer that sort of thing out of the box. Why is that? How do they choose this stuff?

If you were around in the 90s, you may remember a 22lr pistol by Magnum Research that took 15 and 20 round magazines. It was sort of Ruger MKII-ish, and judging by the numbers of them I've ever seen, very few were sold.

After decades of shooting pistols at paper, I have a five round cadence tattooed onto my brain. I can deal with 10 rounds in a magazine because I can follow the same cadence. I once had a 12 round Ram-line magazine, but always loaded it to 10.

People should be able to buy magazines in whatever capacity they prefer, but the 22lr pistol market may reflect a convention amongst customers as much as any real engineering reason.

[veprdude]

I think it's definitely a cost and reliability thing foremost. You don't see Glock redesigning their pistols and mags for higher capacity. In fact, most models never receive an updated magazine style for the same model.

The only ones I can think of is Springfield with the XD to XDM line and Sig with 226 to 228/229 line. Gun is basically the same but mags are different. They made the 9 and 40 slightly wider which allowed a few more rounds for the same mag height. Wider magwell, wider mag, more capacity for the same length of magazine.

You can only do this so much until the grip gets out of proportion to the average (probably man's) hand.

Now when brand new models come out, you better bet the manufacturers are trying to maximize round count with width of grip to fit dead nuts in the middle of the bell curve of the average man's hand. Round count sells, but there is a diminishing return especially when it means the grip is getting wider at the expense of fitting fewer hands. Or the magazine is becoming ungainly long. If they're not doing this they should be.

15-20 in 9mm is the sweet spot until you can make materials thinner to squeeze an an extra round or 2 in.

[Brit]

Magazine capacity? It depends, back in 1980 I read everything I could on fights, good guys against bad guys. Trying to find a common denominator.
Did not take me long, to find out that mostly did not exist.
So there was an average magazine size, that made a given pistol to be able to be holstered and hidden on a belt, also to be deployed in a timely manner.

For quite a few years, a Glock 19 was just right. A 15 round magazine, plus one in the breech, 16 rounds of 9mm hollow points. Plus a Glock 17 magazine as a backup, mostly because a 15 round magazine, inserted in a rush, pinched my hand. All the experts stated that magazines being faulty, was the most common reason to change mags, not running out of rounds.
When I shot the gun games with my Glock 19, I never had any magazine malfunctions! Just changed magazines on lock back. Hence the extended mag' release/lock. To increase the speed of a magazine change.

Then out comes the newest Glock model, the 43X! Ten round magazine, the smallest slimmest and lightest Glock to date! The one I bought, Blue box, with factory-installed Ameriglo night sights. Ten and one seemed capacity enough?
Till the aftermarket, all-steel magazines entered the market place, so back to 15 plus one!

Does everyone remember the old joke? You only can have too many rounds in your magazine, if you are drowning, or on fire!

I coined a phrase MORE IS BETTER ALWAYS as a board member of IALEFI.
Still believe that.

[J.G. Terry]

USP Compact-non historical speculation: I recall during the time of the original high capacity ban of shopping for a 40 caliber HK USP compact twelve shot magazine. The only magazine that showed up had an asking price of $100.00. Later, one retailer was giving away ten shot magazines with the purchase of high capacity post ban magazine.

USP Compact in 45ACP: One factor that dictates the size of the gun is the size of the 45 ACP round. The gun comes across as being designed as a military or police side arm. Consequently, intended use and need for long term serviceability in a medium size hand gun dictated shape, size plus magazine capacity. All these needs were met with a combination of features that came up with this eight shot relatively large handgun. Ambidextrous safety and mag release, plus option of a mode of firing made for easy changes. The gun appears to be made for a market where guns are cleaned once a year whether needed or not. I feel the American market had little to with design or magazine capacity of this gun. One local police force did issue the HK Compact. One complaint was the abrasive character of the grip. That force now uses Glock's.

[USNRet93]

You don't see Glock redesigning their pistols and mags for higher capacity.

That's EXACTLY what Glock did when they designed the 17->19 and 26,
the 22->23 and 27 and 20->29.