Plunk test

[rtpzwms]

Do you consider the plunk test as a valid or invalid test? Please support your position, for or against the test. And what does it confirm, or not to you in your mind?

[Recycled bullet]

Originally Posted by rtpzwms

Do you consider the plunk test as a valid or invalid test? Please support your position, for or against the test. And what does it confirm, or not to you in your mind?

Plunk test is a chambering fitment test. For the semi Auto pistols like 9mm/45 acp etc it is to make sure that the cartridge is head spacing on the case mouth instead of on the bullet. For the revolvers it is to guarantee that the cartridges as assembled will fit in the cylinder.

Are you having an issue loading or firing hand loads?

[totaldla]

Somewhat weird question - this isn't some abstract concept. You don't need to debate this with a bunch of philosophy experts.

The plunk test is simply a bit of practical wisdom - either do it or don't. But if you don't, and you have bullet profile problems, you'll eventually discover why we advocate the plunk test.

[GeauxTide]

I wasted a couple of minutes thinking of a response, but I gave up.

[Nathan]

Valid. Prevents bullet stuck in rifling problem. That’s about it.

How else would I find oal for auto rounds?

[44 AMP]

Do you consider the plunk test as a valid or invalid test?

How could you consider test fitting the ammo into the chamber it is going to be fired from an invalid test???

That just makes no sense at all.

From my point of view, testing the fit of your ammo in the chamber it is going to be fired in is the ONLY valid test, No one's case/cartridge gauge is your gun's chamber. A round that doesn't pass the gauge but goes into the chamber and fires properly isn't a bad round. A round that passes the gauge but won't chamber and fire properly, IS a bad round. For that gun anyway.

I don't see how anyone could look at it another way.

[HiBC]

Some folks use the words "plunk test" without narrowing down what it means.

If you use your gun's chamber,likely you have ammo that will work in your gun.
But if you have a 30-30 and I have a 30-30 we can't count on my ammo working in your gun.
Enter SAAMI. Guns and ammo ordinarily are made to SAAMI standards.
The way tolerancing and gauging works,theoretically we can gauge to confirm that any SAAMI spec ammo will work in any SAAMI spec chamber.
But you have to use the right gauge.
Your chamber will work to check your ammo for your gun. It fits or it doesn't. You can buy a 'plunk gauge" cut to SAAMI "maximum material" dimensions,or a "minimum size chamber" Thats the tightest chamber gun manufacturer should make and sell.
If you use one of these "plunk Gauges" to check your 30-30 ammo,it should work in any SAAMI spec 30-30.

We Handloaders try to fit our ammo to our gun for longer brass life or better accuracy.
To get there we may buy a Wilson or Forster or Lyman "Cartridge brass length or "Headspace bushing gauge"
This is where confusion enters. Cartridges don't have headspace. But a gauge of this type can confirm that a piece of cartridgebrass will have acceptable "Head clearance" in a SAAMI chamber. These bushing guages confirm the distance from the cartridge base or "head" to the cartridges "Headspace control feature" (rim,belt,shoulder or case mouth) is of SAAMI length to give "head clearance" within SAAMI spec.
Now here is a very important point. The bushing gauge is used to check a cartridge LENGTH relative to headspace features. Interference on the cartridge case diameters will confuse/invalidate the results. The bushing gauge must be made OVERSIZE on the Diameters in order to gauge Length.

If you MISUSE the cartridge brass headspace length bushing gauge as a "plunk gauge" it will LIE to you. Do not use it to check diameters.

I've read here on TFL these gauges are useless and just clutter a drawer under the bench.

They are a very useful gauge for setting your resizing die. The key is you have to understand what the gauge is for and how to use it.

Consider a fine Swiss made Etalon vernier calipers. IMO, these are excellent Verniers for taking measurements.
If we use them for another purpose, such as a carpenter's glue clamp or an adjustable wrench, we might be diappointed with the results and declare the Etalon Vernier Calipers a useless piece of garbage cluttering a junk drawer.

In fact, IMO,the Etalon is (IMO) THE vernier to find. (Unless we discuss the Starret Master Bar)

Many tools require Operator Skill to work properly. Even the simplest of them.

[higgite]

Originally Posted by rtpzwms

Do you consider the plunk test as a valid or invalid test?

Valid

Originally Posted by rtpzwms

Please support your position, for or against the test.

Because it works.

Originally Posted by rtpzwms

And what does it confirm, or not to you in your mind?

Cartridge fits chamber, or not. What else could it confirm, or not?

[rtpzwms]

First thank all of you for responding. especially HiBC. I think this test is contextual if you are checking a single load for a single firearm, it has limited validity. But what if you are loading for multiple firearms, are you checking each chamber? When you do this test are you using an assembled firearm, or the chamber removed from the firearm? What happens when you trade one firearm for another in the same caliber do you go back and recheck your ammo?

[jcj54]

Plunk test confirms ammo fits chamber. A fellow brought his new Springfield Garrison 9mm to me complaining it just wouldn't work, light strikes, fail to close reliably etc. I field stripped it and did a plunk test with his ammo. I don't know what brand of remanufactured it was but none of it would go all the way in due to the cases being not sized enough near the base. Got a box of factory new off the shelf. All passed the plunk test. We went out and test fired with factory ammo and it ran flawlessly.
He had never heard of the plunk test. Now he is a firm believer in its value.

[Unclenick]

I suppose you can plunk-test any cartridge, but there are a few exceptions. The idea is that if a round fits entirely into a chamber, it should drop in freely and make a plunk sound as the brass hits the headspacing surface in the chamber, thus proving it fits appropriately. But all it proves is that the cartridge enters the chamber without interference and is not too narrow for the headspacing scheme to stop it from falling into the bore. A moment's thought will reveal several cartridges will plunk in another cartridge's chamber. While it is assumed you are not making that gross error, it nonetheless proves that a cartridge could be a bad fit, function-wise, and still make a plunk sound.

For example, I can get a good plunk out of a 45 Auto round whose case is too short to headspace properly on the case mouth. This happens if you reload a case enough times. Unlike high-power rifle cartridges, the 45 Auto case shortens with each load cycle until the only thing stopping it from going too far forward into the chamber is the extractor hook. Lots of 1911s are loose enough to be headspacing on their extractor hooks even with new brass, so the fact a round will plunk into one of these chambers does not guarantee the best extractor life, and, with lead bullets, which are not hard enough to straighten out well as they start into the chamber throat, they tend to have poor accuracy and cause a lot of leading of they are headspace on the case mouth.

The best fix for a loose fit in the 45 Auto is to stop headspacing on the case mouth and instead seat lead bullets out to headspace on the bullet's contact with the throat leade. You seat the bullet out enough so that when a bullet is touching the throat, the rim of the case is within the extractor space. This can cut group sizes by 40%, IME, and greatly reduces leading because the bullets are no longer scraping themselves against the edge of the headspace shoulder in the chamber. But, with lead being a soft metal, when these rounds are dropped into the case, you don't get a plunk sound. It's more a muffled small thud.

Other instances of bullets seated to touch a throat, even with rifles, will also not make a very satisfactory plunk sound. So, there are some instances where it isn't a great test. You just have to be aware of your load and what to expect from it when testing chamber fit.

[44 AMP]

I think this test is contextual if you are checking a single load for a single firearm, it has limited validity

Not sure what you mean by "contextual". As to limited validity, every test is limited to what is being tested.

But what if you are loading for multiple firearms, are you checking each chamber?

Yes, initially.

When you do this test are you using an assembled firearm, or the chamber removed from the firearm?

Barrel removed, IF the design of the gun allows for easy removal. If not, then I use the assembled firearm.

What happens when you trade one firearm for another in the same caliber do you go back and recheck your ammo?

This is essentially the same question as loading for multiple firearms. So the answer is the same. EACH different gun gets a couple of test rounds chambered. That way, you know if the ammo will chamber properly, or not.

Remember that the plunk test only shows that the round will freely chamber, or not. It does not mean the round will do anything else properly, it doesn't test for that.

They are a very useful gauge for setting your resizing die.

Regarding the use of various gauges for setting my resizing dies, I don't use any. I set my FL resizer per the manufacturer's instructions, which is base of the die in firm contact with the shell holder with all play out of the press. Been loading since the early 70s, load for over 30 different rifle and pistol rounds, never found any situation where setting the FL die that way didn't work.

Those gauges don't clutter up a drawer under my bench, because I simply don't buy them, to begin with. I'm not a match shooter, not chasing the "Nth" degree of accuracy possible. I do what works for me, you do what works for you.

[HiBC]

Regarding the use of various gauges for setting my resizing dies, I don't use any. I set my FL resizer per the manufacturer's instructions, which is base of the die in firm contact with the shell holder with all play out of the press. Been loading since the early 70s, load for over 30 different rifle and pistol rounds, never found any situation where setting the FL die that way didn't work.

Those gauges don't clutter up a drawer under my bench, because I simply don't buy them, to begin with. I'm not a match shooter, not chasing the "Nth" degree of accuracy possible. I do what works for me, you do what works for you.

You do you,I will do me
I agree with you,44AMP! Tight to the shellholder works just fine!
I have found there are advantages to sizing for a specific head clearance.
For myself,a bushing gauge is part of my process. It can double my case life before stretch rings!
But I have no issue with you doing things your way!

[L. Boscoe]

I did not see any love for the 100 round gages, like shokbottle
and the Az.... from Europe.

[Jim Watson]

If you have multiple pistols of the same calibre, plunk different OALs to find the shortest chamber, then load to suit it. (Target shooters may ignore this recommendation.)

I have some of the reverse right now, 9mm SWCs that will only chamber freely in one gun. I will not replace them.

[44 AMP]

I would also mention that checking the ammo for fit in each different gun should not be limited to just handloads. Check your factory ammo in your gun, before you bet your life on it!

Some time back, I heard about fellow who had a problem with CorBon 9mm and his Walther pistols. Everything else chambered fine, CorBon didn't. Other 9mms ran CorBon just fine.

He traded that ammo to a guy who didn't have Walthers and both were happy.

point here is, just because it should work is not a guarantee it will work, so trust, but VERIFY!!

[higgite]

Originally Posted by Jim Watson

If you have multiple pistols of the same calibre, plunk different OALs to find the shortest chamber, then load to suit it. (Target shooters may ignore this recommendation.)

I have some of the reverse right now, 9mm SWCs that will only chamber freely in one gun. I will not replace them.

Exactly that ^^.
My first move with a new to me brand/style of bullet is to plunk test a dummy round at different COLs in each of my pistols until I find which pistol requires the shortest COL. Then load it accordingly knowing that COL or shorter will fit any of my pistols. The shortest COL found with each brand/style of bullet is usually with the same pistol, but there have been a couple of exceptions due to ogive shape. ymmv

[Aguila Blanca]

Originally Posted by rtpzwms

I think this test is contextual if you are checking a single load for a single firearm, it has limited validity.

Yes, it is contextual. You are correct -- all it confirms is that THAT ammunition will fit the chamber of THAT firearm. But ... that's the point.

But what if you are loading for multiple firearms, are you checking each chamber?

Checking each chamber is impractical if you own more than one or two firearms that fire the same cartridge. That's why different companies make ammunition checkers that are reamed to SAAMI minimum chamber dimensions. If a round will "plunk" into a SAAMI minimum chamber checker, it will fit into the chamber of any firearm that is within SAAMI specifications.

When you do this test are you using an assembled firearm, or the chamber removed from the firearm?

It is generally performed with the barrel removed from the firearm (at least, for handgun ammo) so the barrel can be pointed straight down and the round dropped in vertically. It's called a "plunk" test for a simple reason -- a properly fitting round makes a slight "plunk" sound when it seats in the chamber.

What happens when you trade one firearm for another in the same caliber do you go back and recheck your ammo?

Buy a chamber checker.

https://egwguns.com/chamber-checkers/

[44 AMP]

Checking each chamber is impractical if you own more than one or two firearms that fire the same cartridge. That's why different companies make ammunition checkers that are reamed to SAAMI minimum chamber dimensions. If a round will "plunk" into a SAAMI minimum chamber checker, it will fit into the chamber of any firearm that is within SAAMI specifications.

While this is certainly true, I don't see why checking each different gun is "impractical", its not something one needs do often. And, while an ammo checker gauge will tell you what its made to tell you, it doesn't tell you if a specific round will fit in your gun.

Yes, the chamber should be within SAAMI specs, its rare when its not, but while an ammo check gauge tells you the case should fit, it can't tell you about the freebore / leade and the bullet fit in each individual barrel.

It is rare when a round made to spec doesn't fit properly, but its not impossible and chambering the round in the gun, (and closing the action) removes all doubt. Whatever the test round is, if it fits, everything made to those same specs will, also.

SAAMI specs ensure a high degree of uniformity, that's what they are for. SAAMI compliance is also voluntary.

[HiBC]

Without judging either school as "better or worse" I once read there is "Reloading" and there is "Handloading"
Reloading is about keeping a quality ammo supply. The goal is pretty much more or less about re creating ammo that is an alternative to factory loads.

The Handloader might tailor the ammo to optimize it for a particular firearm.

It might not work so well in a different firearm.

Neither school is "Superior". Folks have different priorities. Thats OK.

I might establish (using my bushing gauge) that "tight to the shellholder" results in .005 movement of the shoulder when resizing. That will work, but if I screw the die to contact on a .003 feeler gauge I will get longer brass life.

I don't need universal ammo to fit any SAAMI rifle as I don't share my reloads.

I have actually bought nickel brass for one rifle and WW plain brass for another in the same cartridge because the chambers were cut to different headspace. I lengthend the life of my brass.

But no,I could not shoot ANY 7mm Rem mag ammo in any rifle. Its a tradeoff that suited me.

This is all mostly about centerfire bottleneck rounds.

Carry ammo I use factory loads. Once I select a load, I shoot at least 100 to confirm my gun likes them.
Then that is the load I carry.

[gwpercle]

It is a simple and Valid test .
It shows me my seating depth , especially with cast bullet handgun loads , are seated deep enough to not get caught by the barrels throat/rifling .
When a bullet is jammed into the throat ... it can be a Bear to get unstuck and sometimes extraction will remove a case but leave a bullet lodged in the throat .
The plunk test shows me the round will drop in freely and more importantly ...
... drop out freely .
Your barrel is The Best gauge to use ... trust me on this one !
Gary

[44 AMP]

I once read there is "Reloading" and there is "Handloading"

The problem with that is that any honest definition covers both. Unless the "reloader" is using powered equipment, they are doing it by hand, and that makes them a handloader. And the "handloader" (unless only using virgin brass each time) is reloading ammunition, and that makes them a "reloader".

And no matter which name you choose to use, there is a range of care taken that goes from "finding the absolute best" (of whatever you're after) to "works well enough" for whatever you need the round to do.

One loader can load ammo either way, or both ways, or somewhere in between.

Part of that depends on what you are shooting. The steps done by match shooter and serious varmint hunters with their tuned rifles, to make the best ammo they can, to win a match or zap small varmints at long range are seldom any use in an old deer rife which was never made for more than "minute of deer" to begin with.

Different strokes for different folks, but also different levels of effort for different things in the same folks. I am a handloader who reloads. TO me, the only difference between the two words is the spelling.

[Nathan]

I’m not sure we are all getting what the “plunk” test is and why use it. You drop the round in and the headspace feature, the mouth of an auto round. Hits the end of the chamber. You shorten the round until the bullet doesn’t touch the rifling. This ensures that an auto pistol round does not hang up in the rifling when fed. If it sticks, you can pull the case off the bullet and jam up the whole gun.

Is it the most accurate oal, probably not. Does it prove the round will feed, no. Is it required, no. If you go longer, it will be ok, up to the point that you stick a bullet and the pistol is inoperable. If you go shorter, it too will be ok, until it is short enough to change the pressure to an unsafe level. So why do it?

Because the most important thing in setting oal is to find the max oal that will not stick a bullet. From there, shortening may solve a feeding issue, but not usually.

This is not a case gage replacement, nor is a case gage a plunk test replacement. You need both, or you can reject both. It is your choice. A case gage is to determine mostly if the round fits in a minimum spec chamber. That’s all. I like to know that. Others scoff. Which of us is clearing a practice round mid drill?

[stagpanther]

I learned to use the plunk test for reasons nobody mentioned here; which seems kinda odd to me (or maybe I was just totally missing the point?). I have quite a few earlier glock barrels which are notorious for the infamous "Glock smile" which was a result of the feed ramp being machined into and past the chamber face resulting in potential lack of support of the case head around or just past the web. I found this was more of a case diameter thing (like bullets swelling the case diameter on seating rather than an absolute headspace thing) so when doing the drop test I looked for the thunk which was "proof positive" the case wasn't hanging on the chamber wall while verifying the the where the case rim groove meets the case wall was more or less flush with the chamber face. Eventually became habit for all my semi auto pistol reloads. Am I off-base here?

[Unclenick]

But beware of exceptions. My earlier description of the 1911 is an example, though other designs and older guns, in particular, can have the same issue. The barrel makers all chamber their barrels to SAAMI spec but have no control over how tightly the barrel extension and link lugs will fit an individual gun, so they have to do some compromising that can and does result in excess headspace in some guns. Even match barrels, where you file the barrel extension to fit, have an unknown exact headspace if you don't wait to final ream the chamber after all the other fitting is done. As a result, I saw one estimate 20 years or so back that up to 70% of out-of-the-box non-match grade 1911s were actually headspacing on their extractor hooks instead of the cartridge going into the chamber far enough to "plunk." In other words, excess headspace was the rule rather than the exception. This is where handloading to customize COL for the best function and performance in the individual gun can produce serious precision improvements on the target.



At the last NRA Annual Meeting gun show, one manufacturer told me everything now is being made by CNC gear, so the looseness we used to have to learn how to fit up is dying out. I haven't shopped for new 1911s for decades now, so I'll have to take a tour of the local gun shops and see what I can discern about the state of the art. Meanwhile, you can't be sure the SAAMI spec indications of a cartridge gauge will be applicable to your gun until you prove it.