Its that time once again to read those primer leaves

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Ozzieman

New member
I know the possible issues this kind of a primer strike can be but has anyone ever seen a revolver that hits the primer like this? That was normal?
Personally I wouldn't shoot it till I had it checked. Which for a timing issue could be done in seconds with a rod of some kind.
I was just given >400 38 special cases. Federal once fired and every one, every single one has the same indention on the primer. The case itself looks normal with no bulges or strange markings.
I don't know the gun but after seeing them I sent an e mail out to the owner on what kind of gun it is.
 

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I agree with not shooting it until it's checked. Because the firing pin and the bore are on the same axis, so if the firing pin is off axis, the bullet is leaving the cylinder off axis.

If the cylinder rotates ccw then it should be able to be cleaned up with a file(and that you mentioned, to feel the cylinder alignment) either that or more towards the trigger end needs adjustment if the cylinder ends up in alignment, but the hammer is dropping at the wrong time
 
I would be curious too as to what gun the brass was fired from....a Chiappa Rhino perhaps? I've heard they strike off center. Strike off center could be high or low also, not just to one side or the other. Hard for me to believe someone could fire 400 rounds from a out of time revolver and not know something is amiss.
 
Yes, and if it is to the side, left or right rotation cannot be guessed at unless you know how the cartridge was oriented in the chamber during firing. I would, indeed, inspect the revolver and do the thumb drag test while cocking it single-action to see if the cylinder rotates all the way to the cylinder latch when inertia isn't allowed to carry it there. A worn or broken or mis-installed hand could under-rotate it.
 
I think I disagree. If you think it is a timing issue then that would mean the bullet starts traveling way too early. Maybe the forcing cone could correct that, maybe not. If it didn't I can't imagine someone shooting 400 rounds with lead spitting out the side, and usually in the face. I don't think the off axis theory works either. I'm no primer expert but I think when it goes off its just straight ahead, no side to side action. How would you explain rim fire ammo? I think the gun just happens to hit way off center. It would be interesting to find out why but if he shot 400 rounds then it seems the gun functions okay.
 
That indentation is about 0.030" off-center. Within forcing cone capture range of such an offset. In any event, an inspection is in order to determine the cause.
 
My father had a Taurus M85 that stopped locking the cylinder and had varied hand engagement for each chamber.
Very similar result to the photo.

I never fired it in that condition, but watched him do so to troubleshoot a "hang-fire" situation that he encountered. Yep... just turned out to be primers struck so far off center that initiation took up to half a second, or so.
And even just watching someone fire a couple rounds in that thing, after having identified the huge timing problem, was quite hair-raising.


I've been poking at my grey matter, attempting to come up with some kind of rifle that might be responsible for a strike like that. But, so far, nothing.
 
I've been poking at my grey matter, attempting to come up with some kind of rifle that might be responsible for a strike like that. But, so far, nothing.
Click to expand...

Any rifle chambered for the .38 or .357 COULD be responsible for off center hits like that. It would be slightly out of spec if it did, but it could be, and still work (obviously, the rounds DID fire).

The rounds could have been fired in a slightly out of time revolver, or even one in correct "time" with an offset (slightly out of spec) firing pin location.

Without more info, we' really just guessing.
 
If you think it is a timing issue then that would mean the bullet starts traveling way too early.
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Just for my curiosity but how does a bullet start early? I thought bullets moved out of the case when pressure increased from burning powder that is ignited by a primer, just hit with a firing pin.....
 
but how does a bullet start early?
Click to expand...
What he means by that (I think) is that the primer is fired and the bullet is traveling down the chamber before it locked or was off by some amount.
It left the case early, before the cylinder was in proper position.

It wasn't his gun it was his daughters.
They are bringing it over Sunday.
Attached shows how alike they are. But looking at a lot of them I noticed that a few are slightly closer to center.
Look at second row from the top and the 2nd and 3rd from the right
 

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I too am confused.

Timing is not a travel situation though maybe sound like it.

Indexing would be a better word.

Once the cylinder is advance it locks into place with the cylinder latch (well hopefully)

If once in place is off, then it stays off.

The cylinder is not moving when you fire, its fixed, right or wrong indexing location but fixed .

Bullet travel is not indexed, it should only occur when its latched.

It may wobble as you fire but again that's not timing its simply screwed up device.
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Actually it does wobble, but within the right limits.

that is still not intended motion outside the tolerances, it works right or it does not and then its a matter of how much its out and how much of a problem is there.

One primer is almost struck on the very edge of the pocked.

It looks like a the latch is loose, mis manfuautred, or worn out.
 
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Ozzieman got it. Made sense to me but then I wrote it. If the cylinder rotates 60 degrees (1/6 of 360) for each round and if the firing pin hits the primer say at 59 degrees instead of 60 that might account for the .03 off center (Unclenicks measurement) strike. Somebody with better math skills than I can figure it out. So yes, that shouldn't happen so there probably is a problem with the gun.
 
NO
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RC20 there is no proof of that, I would agree that since ALL of them look alike the cylinder is locked but there is only one thing for sure, firing pin is hitting off center.
Everything else is a moot point till I know more about the gun.
 
Ozzieman,
the same thing can happen if the locking pall is not engaging, and the hand is consistently over-rotating the cylinder; or if the hand is consistently under-rotating the cylinder and not giving the cylinder a chance to lock.

But, as has been said (by you as well)... it's all nearly-worthless banter at this point.
We need the gun.


My bet:
Rohm.
Taurus.
Filthy, nasty, neglected S&W.
 
Agreed. We need the gun.

Still am bothered by the hypothetical and seemly wrong thought process on how the mechanical action works.

1. You pull hammer back, cylinder rotates, you then press trigger.

The cylinder rotating is stopped as soon as the hammer quite moving and before you can squeeze the trigger.

Once the hammer quite moving, there is no more cylinder motion and other than miner loose tolerances (some needed) , the cylinder is still and the bullet is moving. Ergo the forcing cone to allow for that.

Even if the cylinder is not lined up and you drop the hammer, unless the primer is under the hammer nothing is going to happen

Suppose you remove the cylinder latch, if you then spun the cylinder and the hammer hit a primer, it would still stop the cylinder moving.

Its by logic almost impossible for the bullet to be moving while the cylinder is still turning (short of force that breaks the firing pin)

Even fanning a SA the cylinder stops, though it may be a bit off to one side or the other if the latch is worn or loose or faulty.
 
off center primer hits

I own two da revolvers, a s&w m28 and a colt pps, both have a hammer mounted firing pin that pivots on a roll pin, it passes thru a hole in the breach that centers it on the primer, if the hole becomes worn or is slightly larger than it should be the firing pin will not center causing an off center hit, it will be either high or low depending on the gun, the s&w pin is spring loaded to hold it down until it goes thru the hole, the colt is loose and will pretty much fall up or down as it sees fit. just a thought.
 
RC20 said:
Once the hammer quite moving, there is no more cylinder motion and other than miner loose tolerances (some needed)
Click to expand...

It's called inertia. There is angular (rotational) inertia as well as linear. If you perform the thumb drag test on revolvers, it's not uncommon to find ones that don't get the cylinder fully rotated to where the cylinder latch (bolt) engages its notch in the cylinder. But when you aren't dragging your thumb on the cylinder, inertia may still take it there. At the other extreme, if the latch nose is badly worn or if a great deal of powder fouling has accumulated in the mechanism that stops the latch from springing all the way up into position or that causes it to move slowly, then the cylinder, especially if the hammer is cocked fast or double-action firing is rapid, can coast right past the latched position by the time the hammer has completed falling, causing the chamber to rotate past alignment with the firing pin and bore by the time ignition occurs.

I have a suspicion that the latter may be happening here because when I measured the indentation position I used the primer pocket perimeter as a reference diameter and discovered that not only was the impact off center, but the primer had been smeared beyond the primer pocket perimeter on the firing pin mark side. That suggests the cylinder was still rotating at the moment ignition occurred. However, it's not a certainty, as the metal deformation may just have been due to pressure flow around the pin that was squashed flat when the case recoiled back against the breech.

In any event, we're back to requiring the gun be in hand to inspect to settle it one way or the other.
 
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