"Smoke ring' around primers?

[GaryL1959]

Ok, let's see if I can explain this without pictures. Was checking some loads for a straight 243 Winchester, getting ready for an upcoming match. Rifle is a Savage model 12, Criterion 1 in 8 twist, 26 inch tube. Load is : new, unfired Winchester brass, 107 Nosler comp BTHP, Remington 9 1/2 primers, Alliant R-26, starting at 44.8 grains and going to 46.5 in .3 increments, 5 rounds at each weight. Velocities were in line with what was expected, topping out right at 3100 fps.
Here's the issue: at least one case , at each increment, had a distinct "smoke ring" around the primer, no pressure signs as far as cratered / flattened primers, no excessive case head expansion, (less that 1 thou), no hard lift / extraction, etc. No etching or damage to the bolt face. Did not notice any loose pockets while seating the primers, which I wouldn't expect with new brass, even Winchester. Decapped the brass and the 'smoked' ones felt the same as all the rest, and re-primed just to see. Seating new primers with a Lee hand tool, I couldn't feel any difference in the seating pressure.
Soo... what is the smoke ring around the primer a sign of? Been loading and shooting for over half a century, and this is the first time I've seen this...

 

[243winxb]

new, unfired Winchester brass,

Primer backing out a little as the brass expands to the chamber? My guess.

What is head to datum measurements before and after firing?

 

[maxscm]

Guessing game here.
But maybe a projectile touching lands.

 

[muleman69]

Soo... what is the smoke ring around the primer a sign of? Been loading and shooting for over half a century, and this is the first time I've seen this...

I had two out of forty yesterday and still scratching my head? New brass ???

 

[Dusty Stevens]

Loose primer pockets

 

[GaryL1959]

Primer backing out a little as the brass expands to the chamber? My guess.
Haven't measured the datum, but the one case I resized required very little 'force' to bump the shoulder back .001.

But maybe a projectile touching lands.
These are loaded to mag length, so the jump is .030.

Loose primer pockets
My first guess also. I'll pin gage the smoked pockets and the normal ones and see how much difference there is.

Your first clue. “Hornady”.
??? No Hornady components used in the load or mentioned in the question.??


One thing I did notice last night while looking over the rest of this batch of brass. The flash holes are inconsistent as heck, both in shape and size. Could a slightly oversize flash hole leak and cause this?

Thanks.

 

[GaryL1959]

I had two out of forty yesterday and still scratching my head? New brass ???

Yes, new Winchester brass.

 

[JMayo]

Guessing ... it's so much fun !

Irregular seating crush ...?

 

[hogpatrol]

According to this chart, Remington 9 1/2 are the smallest diameter. I'd try another primer and see if you get the same results.

https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

 

[HTSmith]

According to this chart, Remington 9 1/2 are the smallest diameter. I'd try another primer and see if you get the same results.

https://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/

I had this happen with a 260 Remington many years ago. My guess at the time was primer pockets that were on the high side of tolerance and primer diameters on the low side. A switch from Rem 9.5 to Fed 210's solved the problem, though I had to re-tune my load. Even with all that, the primer pockets only lasted 3 loadings with medium loads.

 

[Nature Boy]

thinking “inside the box” here

After shooting a round, do you place the spent case back in your ammo box case head up?

When you do that, burnt powder from the case deposits in the bottom of your ammo box.

When you load more rounds and place them in the box case head down they pick up some of that soot and it looks like something leaked

Can you wipe it off with your finger?

There’s my guess.

 

[muleman69]

Yes, new Winchester brass.

My brass was new Nosler,pockets were tight cool morning and not a hot load? I think it was the GREMLINS again, they seem to follow us around.

 

[expiper]

you should shim the new brass to confirm your excessive headspace ,,,this is a common problem with home made "target" Savage rifles,,,Roger

 

[GaryL1959]

you should shim the new brass to confirm your excessive headspace ,,,this is a common problem with home made "target" Savage rifles,,,Roger

I would make a comment regarding making assumptions, but we all know what assuming does...

 

[Ned Ludd]

Before resizing, how much did the case shoulders actually move on the first firing? In my hands, the shoulders of the calibers I load typically move from about .005" to as much as .009" on the first firing. We usually try to bump the shoulder back only .001" to .002" on subsequent brass preps; however, virgin brass can often be quite a bit "undersized" in a relative sense, in part depending on your chamber specs.

I have observed more than a few competitors that brought prepped virgin brass to F-Class matches with full pressure loads, only to pop a bunch of primers during the matches. The primer pockets were not to blame; rather, the excessive headspace with the virgin brass was the culprit. As soon as the cases were re-sized, the problem disappeared. I can imagine that you might be experiencing a variation on this theme with the virgin brass and [close to] full pressure loads you used. Rather than completely blown primers, there was enough movement of the primer in the pocket to allow some gas leak, resulting in the intermittent "smoke rings" you described. If this is what is happening, the problem should disappear once the brass has been re-sized and the excessive headspace largely eliminated.

 

[muleman69]

Before resizing, how much did the case shoulders actually move on the first firing? In my hands, the shoulders of the calibers I load typically move from about .005" to as much as .009" on the first firing. We usually try to bump the shoulder back only .001" to .002" on subsequent brass preps; however, virgin brass can often be quite a bit "undersized" in a relative sense, in part depending on your chamber specs.

I have observed more than a few competitors that brought prepped virgin brass to F-Class matches with full pressure loads, only to pop a bunch of primers during the matches. The primer pockets were not to blame; rather, the excessive headspace with the virgin brass was the culprit. As soon as the cases were re-sized, the problem disappeared. I can imagine that you might be experiencing a variation on this theme with the virgin brass and [close to] full pressure loads you used. Rather than completely blown primers, there was enough movement of the primer in the pocket to allow some gas leak, resulting in the intermittent "smoke rings" you described. If this is what is happening, the problem should disappear once the brass has been re-sized and the excessive headspace largely eliminated.

Well said