How many rounds...
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I'm usually pretty stoked when I get a new pistol, it doesn't take more than a day or two before I have 4 or 500 rounds through it, so I rarely think about it as "reliability testing". But I know very quickly of there's a problem. I couldn't imagine dropping 3-500$ on a new piece and only putting 50 rounds through it. That's no fun
g.willikers
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There's really no way to tell if a pistol will act up, no matter how reliable it's been in the past, or with what ammo.
It's better to rely on one's ability to get a miscreant shooter back in action as fast as possible, instead of solely relying on the gun and ammo choices.
Equipment can always fail.
But skill is forever.
The convincer for me was a pistol that ran perfectly with everything up until 500 rds.
Then it steadily deteriorated until at about 1500 rounds it became just about useless, but provided a lot of good jam clearing practice.
It's better to rely on one's ability to get a miscreant shooter back in action as fast as possible, instead of solely relying on the gun and ammo choices.
Equipment can always fail.
But skill is forever.
The convincer for me was a pistol that ran perfectly with everything up until 500 rds.
Then it steadily deteriorated until at about 1500 rounds it became just about useless, but provided a lot of good jam clearing practice.
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"already proven gun" "thousands of trouble-free rounds"
The thread, as I understand it, is about a newly acquired gun that will/may be used for SD. It would be pointless to talk about testing a currently owned gun that has been fired thousands of rounds with no problems.
Jim
The thread, as I understand it, is about a newly acquired gun that will/may be used for SD. It would be pointless to talk about testing a currently owned gun that has been fired thousands of rounds with no problems.
Jim
Limnophile
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The answer can be obtained objectively if you first subjectlively specify:
- the confidence level you're willing to live with, and
- the minimum reliability rate you're willing to live with.
For example, if you want to be 95% confident that your carry ammo will work in your pistol at least 95% of the time, you need to fire 59 trials with 0 failures to feed, fire, or eject. I denote this as follows:
- 95% confidence/>95% reliability ---> 59 shots w/ 0 failures.
Other combinations of potential interest:
- 98% confidence/>98% reliability ---> 194 shots w/ 0 failures
- 99% confidence/>99% reliability ---> 458 shots w/ 0 failures
- 99.9% confidence/>99.9% reliability ---> 6,898 shots w/ 0 failures
- 99.99% confidence/>99.99% reliability ---> 116,406 shots w/ 0 failures.
As you can see, there is a practical limit, as no pistol would survive being tested to 99.99%/>99.99%. (If it did, the number of parts replaced would make it a different gun at some point.) There is no need for the confidence level and minimum reliability rate to be identical; for example:
- 95% confidence/>99% reliability ---> 298 shots w/ 0 failures
- 95% confidence/>99.9% reliability ---> 2,992 shots w/ 0 failures.
Because the system being tested for reliability consists of the ammo, a magazine, and the pistol, I can see a case being made for firing at least 59 rounds of the carry ammo without failure from each mag before certifying a given ammo/mag/gun combo as confidently reliable for carry. Ninety-five percent reliability sounds low for a tool you're betting your life on, but the reliability value specified is the lower bound of the one-sided confidence bound of the unknown reliability, and with 59 failure-free trials, the best estimate of that unknown reliability is close to 100%.
- the confidence level you're willing to live with, and
- the minimum reliability rate you're willing to live with.
For example, if you want to be 95% confident that your carry ammo will work in your pistol at least 95% of the time, you need to fire 59 trials with 0 failures to feed, fire, or eject. I denote this as follows:
- 95% confidence/>95% reliability ---> 59 shots w/ 0 failures.
Other combinations of potential interest:
- 98% confidence/>98% reliability ---> 194 shots w/ 0 failures
- 99% confidence/>99% reliability ---> 458 shots w/ 0 failures
- 99.9% confidence/>99.9% reliability ---> 6,898 shots w/ 0 failures
- 99.99% confidence/>99.99% reliability ---> 116,406 shots w/ 0 failures.
As you can see, there is a practical limit, as no pistol would survive being tested to 99.99%/>99.99%. (If it did, the number of parts replaced would make it a different gun at some point.) There is no need for the confidence level and minimum reliability rate to be identical; for example:
- 95% confidence/>99% reliability ---> 298 shots w/ 0 failures
- 95% confidence/>99.9% reliability ---> 2,992 shots w/ 0 failures.
Because the system being tested for reliability consists of the ammo, a magazine, and the pistol, I can see a case being made for firing at least 59 rounds of the carry ammo without failure from each mag before certifying a given ammo/mag/gun combo as confidently reliable for carry. Ninety-five percent reliability sounds low for a tool you're betting your life on, but the reliability value specified is the lower bound of the one-sided confidence bound of the unknown reliability, and with 59 failure-free trials, the best estimate of that unknown reliability is close to 100%.
rt11002003
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I like Limnophile's post. My reply to the OP was to be "define reliable".
I bought a Kimber SOLO 9mm which writers all over the web beat the he** out of about reliability for almost two years. I like the little sucker. It is accurate. Easy to carry.
Reliability was a concern. I quit trying to shoot round nose ammo in it, even if the ammo met the weight specs. It is said after 300 rounds, it will shoot anything. I'm past 300 rounds; haven't tried round nose ammo since about 15 rounds.
With the correct, factory recommended ammo that little gun hasn't had a hiccup since I discovered proper handling after three mags of ammo. One, lock the slide back. Two, fully insert the loaded magazine. Three, release the slide by pulling it aft and let it go. Four, pull the trigger. When the magazine is empty, the slide locks back. Pickup at Step Two and repeat. Hasn't failed in approx. 300 rounds using three different brands of ammo.
I bought a Kimber SOLO 9mm which writers all over the web beat the he** out of about reliability for almost two years. I like the little sucker. It is accurate. Easy to carry.
Reliability was a concern. I quit trying to shoot round nose ammo in it, even if the ammo met the weight specs. It is said after 300 rounds, it will shoot anything. I'm past 300 rounds; haven't tried round nose ammo since about 15 rounds.
With the correct, factory recommended ammo that little gun hasn't had a hiccup since I discovered proper handling after three mags of ammo. One, lock the slide back. Two, fully insert the loaded magazine. Three, release the slide by pulling it aft and let it go. Four, pull the trigger. When the magazine is empty, the slide locks back. Pickup at Step Two and repeat. Hasn't failed in approx. 300 rounds using three different brands of ammo.
rt11002003
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Quote: Generally, about how many rounds does it take to show that a particular type of ammunition is reliable with a certain semi-auto handgun?
Some guns don't like some ammo. I had a Hammerli Xesse Sport .22 LR. I shot, or tried to shoot, every brand I could find. Some would go 30 rounds OK; some would only go a couple of rounds. I never knew if I could depend on a specific brand. Until.
I found it would accept Armscor .22 LR. Sometime after a couple of hundred rounds without failure, when cleaning the Hammerli, I discovered a cracked frame. Sent it to Walther; they found the barrel was also cracked.
For that specific gun, I couldn't depend on any ammo, of that tested, except Armscor. They were all unreliable in the Hammerli, in my mind, except Armscor ammo.
I have no idea what caused the barrel and frame to crack, nor when it happened. It was just the right lighting conditions when I found the crack.
Just the other day, I finished a case of 5,000 rounds of the Armsco ammo; shooting it in five different pistols and two rifles. I've had a couple of FTE and a half dozen light strikes, a fault of the gun.
If I can shoot a box of 50 rounds in a specific gun, without any failures, I'll feel the ammo is reliable. But, if it's a carry gun, or home defense gun, I want to feel it will fire if I need it. I get comfortable with those guns and their ammo at around 200 rounds. I shoot them monthly, at least 25 rounds.
Some guns don't like some ammo. I had a Hammerli Xesse Sport .22 LR. I shot, or tried to shoot, every brand I could find. Some would go 30 rounds OK; some would only go a couple of rounds. I never knew if I could depend on a specific brand. Until.
I found it would accept Armscor .22 LR. Sometime after a couple of hundred rounds without failure, when cleaning the Hammerli, I discovered a cracked frame. Sent it to Walther; they found the barrel was also cracked.
For that specific gun, I couldn't depend on any ammo, of that tested, except Armscor. They were all unreliable in the Hammerli, in my mind, except Armscor ammo.
I have no idea what caused the barrel and frame to crack, nor when it happened. It was just the right lighting conditions when I found the crack.
Just the other day, I finished a case of 5,000 rounds of the Armsco ammo; shooting it in five different pistols and two rifles. I've had a couple of FTE and a half dozen light strikes, a fault of the gun.
If I can shoot a box of 50 rounds in a specific gun, without any failures, I'll feel the ammo is reliable. But, if it's a carry gun, or home defense gun, I want to feel it will fire if I need it. I get comfortable with those guns and their ammo at around 200 rounds. I shoot them monthly, at least 25 rounds.
boondocker385
New member
I shoot 50 rounds through each of .my carry mags with the ammo I carry and another 50 of my reloads that mimic that carry ammo (yes I know it isn't the same).
There can be no specific number of rounds as there are too many variables in pistols and ammunition. Many "torture tests" have been done on major brands and written up in the gun mags but they relate to THE TESTED PISTOL only, your pistol and/or ammo may react entirely different. Shoot what ya got until YOU are satisfied the combination is what you will cover your butt with.
Limnophile
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My impression is that everyone herein has been assuming the OP was asking about ammo reliability in one given pistol. It has been correctly pointed out that testing should be pistol-and-magazine-specific, as a given magazine can pose problems. If one wants to ne persnickety, testing should also be specific to the ammunition lot, as I assume the manufacturer's quality control is done on a per-lot basis. It probably only pays to be this persnickety if you buy a large amount of ammo at a time. Personally, being cheap, I prefer to do most of my shooting with FMJs that are exterior-ballistically equivalent to my self-defense carry ammo.
Other variables to consider include:
- How clean the gun is. If you clean your pistol after every range session and tested your carry ammo during such a session, one can't reliably extrapolate the test results to the pistol if it hasn't been cleaned in a year. Keep your cleaning habits consistent.
- Gun modifications. Changing your lube may or may not alter your gun substantially, but changing your hammer spring may well do so. Any substantial modification merits a new round of carry ammo reliability testing.
It is the manufacturer's responsibility to ensure his ammo is generally reliable across platforms. Firearms fora, like this one, or, better yet, one focused on your pistol of choice, are good places to find out whether a given manufacturer of a given line of his ammo is generally reliable or not.
One can use this online binomial confidence limit calculator to obtain the results I posted above: http://statpages.org/confint.html. Use a one-sided confidence limit, because you are only interested in the lower bound of the reliability rate (or, equivalently, the upper bound of the failure rate).
Other variables to consider include:
- How clean the gun is. If you clean your pistol after every range session and tested your carry ammo during such a session, one can't reliably extrapolate the test results to the pistol if it hasn't been cleaned in a year. Keep your cleaning habits consistent.
- Gun modifications. Changing your lube may or may not alter your gun substantially, but changing your hammer spring may well do so. Any substantial modification merits a new round of carry ammo reliability testing.
It is the manufacturer's responsibility to ensure his ammo is generally reliable across platforms. Firearms fora, like this one, or, better yet, one focused on your pistol of choice, are good places to find out whether a given manufacturer of a given line of his ammo is generally reliable or not.
One can use this online binomial confidence limit calculator to obtain the results I posted above: http://statpages.org/confint.html. Use a one-sided confidence limit, because you are only interested in the lower bound of the reliability rate (or, equivalently, the upper bound of the failure rate).
I have always been the 500 round break in type of guy. But in reality I can't name one weapon that had a problem after two hundred rounds. Guns and Ammo just did a test on mini 9's and logged all failures from shot one to shot 650. Most problems happened in the 0 - 200 round count and three never failed. So I said 200.
I voted 50. Guns are as we all know mechanical devices. failure can occur at ANY given time, 51, 101, 201,501 and so on and so on.
So now my question at what point is enough, enough given my above statement.
How many times do folks leave for vacation and have had their vehicle checked over before the trip and wala, a breakdown on the road.
So now my question at what point is enough, enough given my above statement.
How many times do folks leave for vacation and have had their vehicle checked over before the trip and wala, a breakdown on the road.
Limnophile
New member
If one subscribes to a necessary break-in period, reliability testing should be initiated only after the pistol is broken in. The break in, of course, can be done with cheap FMJs.
Limnophile
New member
Good point.
This online calculator -- http://www.measuringu.com/wald.htm -- provides four alternative calculations for the one-sided lower confidence bound of reliability, and four alternative estimates of the best estimate of the reliability rate. For the confidence bound I'll go with the exact calculation. For the best estimate it's tempting to use the maximum likelihood estimate (MLE), but if you experience no failures that MLE offers a false sense of security.
For example, after any break-in period, you fire 50 rounds from your clean pistol using a single magazine -- 50 rounds passed out of 50 tested, you opt to use a 95% confidence level assuming the actual reliability (completion on the calculator) rate is close to 1. The exact confidence bound shows you can be 95% confident your pistol-mag-ammo is at least 94.18% reliable. The MLE shows, misleadingly, that the pistol-mag-ammo is, on average, 100.00% reliable. The website recommends using the LaPlace approximation as the best estimate of average reliability: (rounds pass + 1)/(total rounds tested + 2) = 98.08%. The calculator offers two other options for estimating average reliability, and the Wilson approximation (97.43% in this case) is dependent on the specified confidence level. I'll put my money on the Wilson approximation.
There are only two ways to increase your estimate of reliability (assuming no failures occur during your test) -- lower your confidence level (which I would not advise), or increase your number of trials. There are no shortcuts.
To answer your question -- what constitutes enough is purely subjective. It depends on what level of confidence you wish to have and what lower bound and best estimates of reliability you are willing to live with. Take into account how much you are willing to spend on premium self-defense ammo, and how much time and patience you have.
Most statistics practitioners use the 95% confidence level as a default; some use 99%. But, the choice is yours. In many matters, including semiauto pistol reliability, there is no such thing as certainty.
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Brotherbadger
New member
I'd say over 500 rounds for me to be comfortable with a pistol.
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