This guy chambered the same 9mm round 100 times...

[ArcadiaGP]

Pretty amazing result. A lot of bullet set-back.
Just a good reminder to refresh your ammo after a certain amount of time

Check the album here for a few pics and angles.

9mm Winchester White box 100x chambering - Imgur

Question - How do you think this round would behave if it were fired?

Here's just one of the images:

 

[Dead Duck]

Just one word comes to mind.

 

[shibumiseeker]

What it would do depends entirely on the powder, bullet weight, and gun. It'll increase the velocity and pressure some, but probably not enough to be dangerous as it is WWB and not some +P+ round.

 

[chezuki]

I would imagine the lack of powder and primer would play a factor in how dramatic the setback appears.

I'd like to see a similar experiment with a live round including OAL measurements. I hypothesize the cartridge would be safe to fire.

 

[Gluemanz28]

My question was the set back after the first time the rounds was chambered? It doesn't say. I would have like to have seen the round at different chamber counts. 1, 5, 10, 25, 50, and 100
This brings up the OAL question. Is OAL determined by load data or gun chamber?

 

[jtwilson3]

Does this include chambering a round without racking the slide? Like I put the slide lock on, put the round in the chamber, release the slide then load the magazine. Do you believe that this would hurt the round any? And I am curious how this goes with Hollow Points rather than FMJ's.

 

[bigtank1982]

Does this include chambering a round without racking the slide? Like I put the slide lock on, put the round in the chamber, release the slide then load the magazine. Do you believe that this would hurt the round any? And I am curious how this goes with Hollow Points rather than FMJ's.

I've heard that dropping a round in and closing the slide like that is bad for the extractor, but that might be false info.

I don't worry about setback so much. Once my carry and nightstand guns are loaded they stay that way until I take them to the range. Would take me a very long time to get 100 cycles on that top round.

 

[Gluemanz28]

I buy my .40 HP ammo 1000 at a time for the same money that WM charges for FMJ FP target rounds. I practice and EDC the same round so not an issue with me.

 

[USMC-Johnson]

if i get a chance to grab some calipers tomorrow i will repeat this with my glock and my sig...

 

[HavokCycle]

i usually keep the same bullet in the chamber in my loaded guns. ive indeed noticed blemishes on some of them, rifle rounds mostly. they've been re-chambered probably a couple dozen times, and in one case i discarded a round because it jammed and dented the case. my fault on that, my hand rode the charging handle.

 

[cbhausen]

I keep digital calipers on my desk at work and I have checked the overall length of the top two Federal HST cartridges in both my Glock 19 and Beretta Nano (I load both with a full mag and one in the pipe). I've swapped the top two cartridges in both pistols dozens of times and they always measure 1.100" give or take a couple thousandths.

Edit: I slingshot the slide on both. Ingrained habit because the Nano has no slide stop lever. And yes, my employer is gun-friendly. I'm self-employed.

 

[midget]

Yep, this is not surprising at all. Unless the round you use has a death grip crimp (which will cause all sorts of other problems), this will eventually happen. It is the result of the bullet being pushed against the feeding ramp and has nothing to do with the amount of powder that is in the case.

 

[cbhausen]

I believe inertia (rather than friction with the feed ramp) causes bullet set-back. The projectile creeps back into the casing because it tends to remain at rest as the cartridge casing is smacked forward by the side.

 

[marv]

My M642 has been loaded/unloaded a few times for various reasons and I have not noticed a single thou. of setback.

 

[85t5mcss]

I believe inertia (rather than friction with the feed ramp) causes bullet set-back. The projectile creeps back into the casing because it tends to remain at rest as the cartridge casing is smacked forward by the side.

What about the impact and friction of the projectile hitting the ramp while the case is being shoved into it?
I have no scientific data but I see where it could be both. But if the inertia does it then does that mean the bullet comes out of the brass as it chamber on straight wall cases?

 

[in625shooter]

What about the impact and friction of the projectile hitting the ramp while the case is being shoved into it?
I have no scientific data but I see where it could be both. But if the inertia does it then does that mean the bullet comes out of the brass as it chamber on straight wall cases?

This is pretty much what happens. What the OP showed at 100 times generally will start happening around chambering the same round at the 20 time mark and start getting significantly deeper to a point the powder keeps it from going any deeper. I deal with duty guns and it is a common occurrence after many chambering's the bullet starts to set back. When it is repeatedly slammed into the feed ramp time after time the crimp will only hold the bullet in place for so long.
Generally when it becomes noticeable we discard that particular round.

As far as inertia issues that is generally an issue with hand loaders not applying a proper crimp. In autos you will generally have the issue of the round not chambering properly.

Some firearms are more forgiving than others.

.

 

[nipprdog]

Like I put the slide lock on, put the round in the chamber, release the slide then load the magazine.

DON'T DO THAT!

I've heard that dropping a round in and closing the slide like that is bad for the extractor

Yep.

 

[88E30M50]

Bullet setback can really impact the pressures a gun sees when shooting. If you run a good, stout SD round, it may not take much to push pressures over the limits. For instance, I have been loading 115g 9mm with 6.9g HS-6 with an OAL of 1.169. The max pressure (as predicted by Quickload) is 32,745 psi which is well within the 35,000 SAMI max for a 9mm. If I load that same charge to 1.125, which is the spec if using some HP bullets, the pressure spikes at over 41,000 psi which is well over the spec. That .044 difference can be missed visually unless you sit the bullets side by side and could easily happen if the same round is loaded over and over.

 

[nebulous]

Every few years a cool new carry round comes out, so I buy a box. I shoot a few rounds to make sure it works well in my gun, then I shoot up the stuff that I was using for the last few years.

 

[IndianaResident]

I have a couple of rounds out of a box of Hornady defensive ammo (polymer tipped, I don't remember exactly which type) push the bullet in the case enough that the lip of the case stuck over the widest portion of the bullet and would hang up on the bottom edge of the feedramp. That happened in probably less than 50 chambering per round for I think 4 before I scrapped the whole round.

I haven't had that issue with the department issued Winchester Ranger hollow points, and the same 2 rounds have seen probably 100 per since its been a year of service on this box.