One of the recent posts about a P320 potentially firing out of battery got me curious, so I did a little quick test last night. I used a pencil in the barrel to test one of my P320s. The pencil would definitely get launched when the trigger was pulled with the slide slightly retracted, maybe 1/8 inch. At about 1/4 inch I got a dead trigger.

I'm going to do a little more research with actual measurements, and also try it with my second P320 and my P329.

My question is, when exactly is a pistol considered out of battery? I'm pretty sure it's not determined by any set distance of slide travel. Is it as soon as any relative motion is detected between the slide and the barrel, or does the movement have to be more pronounced, say a definite downward drop of the barrel?

My definition would be when the cartridge is not fully in the chamber. If it's a Browning design (tilting barrel), if it started to unlock from the slide, even if the round is still fully chambered, I would also consider this out of battery, as the idea of the locking is to slightly delay the rearward motion in order to allow pressures to drop. If it's already unlocked, it can move rearward while the pressures are still high and potentially blow out the case.

So, does the slightest bit of relative motion between the slide and the barrel constitute unlocking, or does there have to be a visible gap, test with a feeler gauge, etc?

quote:

Originally posted by RichN:
So, does the slightest bit of relative motion between the slide and the barrel constitute unlocking, or does there have to be a visible gap, test with a feeler gauge, etc?

No. Pull back your slide SLOWLY. You'll see that it takes some distance before the barrel moves relative to the slide. This provides extra mass during cycling to slow down the unlocking process and allow chamber pressure to drop sufficiently enough for extraction.

quote:

Originally posted by RichN:
One of the recent posts about a P320 potentially firing out of battery got me curious, so I did a little quick test last night. I used a pencil in the barrel to test one of my P320s. The pencil would definitely get launched when the trigger was pulled with the slide slightly retracted, maybe 1/8 inch. At about 1/4 inch I got a dead trigger.

As long as the barrel hood is still in full contact with the breech face the barrel is still locked into the slide. Any movement of the barrel, either vertically or horizontally, means the barrel is unlocked.

Well, since you said relative movement between slide and barrel, I would say yes, it's starting to unlock. But the slide and barrel can move rearward together on the frame with unlock starting.

On a tilting-barrel action, slowly retract the slide and you will see the barrel moving with it for ~1/8 of an inch, then it starts to drop down, which unlocks the breech. I would define this point as being "out of battery." But with the trigger disconnect found on almost every pistol, pulling the trigger should not be able to trip or release the hammer or striker. So with guns in proper working order, where does this "OMG it fired 'out of battery!!!'" business come from? I don't buy it.

If a tilt lock barrel is "out of battery" to the point of substantially reducing or eliminating locking surface contact, the firing pin is no longer aligned with the primer. So how does it fire "out of battery"?

The extractor holds the round against the breech face, so the firing pin/striker is certainly in line with the primer still.

On every pistol I have tried it on, the trigger disconnects about the same time the barrel hood starts to drop down.

The trigger bar disconnect is usually actuated by interaction between a tab on the trigger bar and a cutout in the slide. I don't have a 320, so I'm guessing it's the same.

Under normal operation, the barrel starts to tilt and unlock when the underlug contacts the locking insert (in a P-series, anyway).

If a barrel does not seat correctly in the slide on chambering, isn't it possible for the slide to be forward enough for the trigger bar tab to be in the cutout (i.e., NOT disconnected) and yet the barrel to be slightly low and partially unlocked? Or would/should the barrel lug prevent the slide from moving that far forward?

I can imagine in that situation, although the case is fully supported when the striker/firing pin hits the primer, the usual delay offered by the rearward movement of the slide and barrel together is not there, and the barrel starts to retract the case while pressures are too high. That could blow out a case or cause a separation, as BuddyChryst suggested.

If you are looking to see if it fires out of battery you are doing it backwards. Pulling the slide open and working the trigger isn't going to tell you anything. Why would the slide be retracting as you were trying to discharge a round?

You need to be closing the slide as you are working the trigger to determine if it will fire out of battery.

I check my Sig's by pinching a narrow strip from a paper business card (which is about .010" thick) between the barrel and breech block. None of them have ever dropped the hammer with that piece of paper pinched in there.

quote:

Originally posted by GP229:
If you are looking to see if it fires out of battery you are doing it backwards. Pulling the slide open and working the trigger isn't going to tell you anything. Why would the slide be retracting as you were trying to discharge a round?

You need to be closing the slide as you are working the trigger to determine if it will fire out of battery.

I check my Sig's by pinching a narrow strip from a paper business card (which is about .010" thick) between the barrel and breech block. None of them have ever dropped the hammer with that piece of paper pinched in there.

It seemed to me it would unlock at the same point while being retracted that it locks while closing, and it was easier to see when something started to move as opposed to stopping, but I can try it the other way.

I just got done with a some testing with my P320s. On both of them, the trigger is dead until the slide is about 1/8" from being fully forward. On one of them, the barrel locks up about 1/16" before that. On the other one it locks up almost a full 1/8" before the trigger will engage.

Based on this, there is probably a very slim possibility that a particular combination of components might lead to enough tolerance stacking to allow the trigger to engage while the gun is out of battery, or at least just barely in battery.

I'm not concerned about my P320s, but I will perform this test anytime I assemble a new combination of slides and frames.