Something that could help
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Itās called plunk test and it actually should be done with every new ammo we start shooting.
It is of course impossible to run the test for every single roundā¦ but factory ammo shouldnāt have any abnormalitiesā¦ however as we saw, Fiocchi was caught on this.
Anyway, I wouldnāt spend a lot of time on that. If you think Fiocchi is not good, you donāt shoot it anymore.
It is like choosing gasoline for your car. Most of gas stations are using the same sourceā¦ but somehow the car doesnāt like CITGO or SPEEDWAY or BPā¦ 
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There is a difference between gas.
For example, the additives in Top Tier gas do make a difference and this has been experimentally third party verified.
Iām fortunate in that where I live, the least expensive gas available also happens to be Top Tier so itās not even like itās just a money grabā¦some gas stations are just better than others
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On my critical 2nd cup of coffee I set out the last 50 round box tray of the Fiocchi 115 grain FMJs and did the test with the M2.0 barrel. I focused on the sound, visual, and feel. 49 were identical. The tenth one stopped 1/16" from seating or battery, required some finger pressure to seat, and didnāt drop right out. Micrometer comparisons were inconclusive, but the case could have been .001 out of round. The plunk test. Itās not just for reloads anymore! Iāll look over the JHPs before the next range trip. Thanks Jerzees. Learning the language is learning the culture. -KL
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You found the best way to know your firearm and ammo that reliable runs in it.
For training ammo, you shouldnāt care a lot. Itās really hard to test all rounds, however all depends how much do you train and shoot.
But for defensive ammo carried on you I strongly recommend to do plunk test for each individual round.
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Sound like an āMIAā (Murphy is alive) failure to me.
Try this
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I asked because some firearms are harder on loaded rounds than others. Sharper angles of insertion between the magazine and the chamber, rough ramps and sharp edges to the chamber all contribute to bullets being pushed back into cases and messing the case mouth and overall case enough to cause chambering issues and sometimes raise pressure in rounds that are chambered multiple times.
Thatās why in general it is recommended that you never rechamber a particular round more than once before firing and many folks that routinely load/unload their guns should rotate the extracted unfired round to the bottom of the stock to avoid routinely unloading and chambering of the same round over and over again.
My Glocks have never given me any heartburn about this but Iāve had some experiences with other high end handguns which I will not name because I donāt even want to go down this rabbit hole.
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I do have defensive ammo that is loaded-chambered-unloaded from the top of the mags as I rotate concealed carry micros Shield+, P365+, Kimber R7, Glock 43x. Loaded mags are safe-stored until needed. The M2.0 is an outdoor hiking carry and is seldom rechambered, I will follow your recommendation to rotate extracted live rounds, and study chamber conditions during maintenance as possible. I appreciate all reminders concerning safety and dependability.
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Army safety officer : āThere are no dangerous machines, only dangerous machine operators.āā¦(āMurphy and yer bro Ginchy: STAND DOWN !ā)
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have almost a box of 20 self-defense rounds of 38 super ammo that does thatā¦ wont chamberā¦
some almostā¦ some maybe 50% of the cartridgeā¦ never chambered beforeā¦
thinkin quality control slipped up?.. is made by Sig Sauerā¦
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Doesnāt always need to be manufacturing QC. Imagine for a second a delivery guy or stock clerk drops a case of ammo rim side down. The potential to ruin a whole box or even a whole case of ammo by careless handling is real. And thatās why we donāt blindly buy a batch of new SD ammo and happily load a few mags and go off into the world.
We are working with firearms which have tolerances measure in thousands of an inch in some cases. Soooo we test it first!!!
I had a friend in law enforcement that gage checked every single round of SD ammo that was allotted to him by his organization after watching a whole pallet of it being dropped on delivery by an incompetent worker. It might be overkill be he swore he NEVER had an issue when it counted.
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If specs for the ammo can have deviations in tolerances, so can specs for barrels, feed ramps, magazine openings, etc. I suspect the biggest problems will come from a situation where extreme tolerance differences happen in several different parts at the same time.
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On to JHP defensive rounds with a more precise āplunkā tester. I tested the ammo in 6 preloaded mags in preparation for an upcoming range day. There were single stacks, double stacks, the M2.0 and four micros described earlier in this topic. 2 mags of Hornady all a consistent glide to seat, tip & gravity slide back, 2 Fiocchi were fine but every 4th or 5th round would seat a little tighter than the others, needed a tap from my non-gunsmith Papermate Erasermate pen/extraction tool. On 2 of the mags the fit was similarly inconsistent, but 1 of those rounds did not plunk in but stopped at the rim, could not be thumb forced (no tapping near the primer allowedā¦! ) and had to be tapped out. Thatās the one in the photo. The micrometer showed the case was possibly .xxx5 (ten-thousandths?) larger than the others at the back, the rim vaguely thicker, length the same. (A random sampling of a 50-tray of JHP Winchester was as precise as the Hornady.)
The sticking round may have been slammed into the chamber, fired, and been extracted? Or not. Iām going to mark it and try it at the range in the Shield+ mag I found it in. As suggested by Jerzees and others testing everything that is used for home and personal CC defense is a wise decision. Thanks all for your contributions.
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I start thinking that the problem is with the barrel (actually the chamber) which seems to be undersized.
M&P 9 M 2.0 is not a picky handgun and it has a pretty good tolerance accepting every factory ammo.
All depends on interpretation of the word slammed.
If you cannot insert the bullet into the chamber with gentle pressā¦ then answer is no.
Keep checking different ammo to find the one that works reliably. If you see inconsistency within the same box of ammo, definitely reach out to Smith&Wesson with this issue.
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Question for you ā are you doing plunk test on handgunās barrel or cartridge gauge?
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All the testing and comparisons done yesterday were done with the Dillon Precision 9mm gage that I purchased for this purpose. I used the barrel(s) of several pistols initially and was motivated to add the spec gauge to get a reference. By āslammedā I was trying to describe the action of the slide and recoil spring as the round would be chambered in operation. Gentle thumb pressure would not seat the round(s) that were in question flush into the gauge or barrel, so at least by the factory machine tolerances of the gauge, they were off spec. So far the inconsistencies have appeared in boxes of both FMJās and JHPās from the same manufacturer.
Iāll have more info to digest after upcoming range visits. The range log is getting full of little shooting shorthand symbols regarding the performance of both the shooter and the ammo used- brand, bullet type, weight, etc. I really appreciate taking time to learn how to think about these issues, not just what to think .
My steel 3" 357 and 2" 38sp snubbies are seeming more confidence inspiring latelyā¦
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The Idea of plunk test is to check proper fit between ammo and chamber.
Because of thousands of inch tolerance in specs, you may not find the real issue using gauges.
Gauge is good to check if you are doing good job reloading the ammo, not finding the problems with your firearm.
Gaugeās size is the maximum of allowed ammo size, but your chamber might be in minimum site of the specs.
Regarding slamming ammo into the chamber by slide - this is the part of firearm operation, so if you are not helping the slide to do its job, if the round is chambered by itself - all is good. If you experience failure to feed caused by sizing you should never force the slide to push the round into the chamber.
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if you can use the actual barrel it will be fired through that might work???
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Since itās certainly true that the barrel chamber is the test of ammo compatibility, I just field stripped the M2.0, and four micros: Shield+, p365+, R7Mako, and G34x. The round that failed to fit flush in the reloaderās gauge failed to drop/plunk fully into any of those chambers. I used thumb pressure, but did not attempt to chamber it by racking the slide. Iāll save that for the range when I have the gunsmith assistance available.
The Smiths were the tightest, Kimber & Glock in the middle, and the Sig was most forgiving. I could pull that out with fingernails, the others I had to tap out. So far my thinking is leading to being ammo centered, inconsistent and outsized ammo, not brand centered or minimum spec chambers. Iāll do a staff supervised range test with the Shield+, since that was the mag I found the suspect in. Thanks keeping the observational wheels turning. Stay vigilant.
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Old dudes like us have to be straight shooters. Check out the reply to Jerzees where I described the barrel comparisons. That actual barrel will meet that outsized round this week. Carry on strong.
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