Ejection print ALWAYS pressure sign?

[Burras]

Do prints from the ejector in the case ALWAYS mean to high pressure?

I wonder if a hint of ejection mark ALWAYS means that you got to high pressure?

I started a break in of a new barrel in 6.5x47 Lapua and shot loads, 3 by 3 from 35.5-37gr. Since it was a break in I obviously cleaned the barrel between the shots and got no signs of heavy boltlift through the ladder. The velocity during the loads did not seem to flatten out.

I don't know if the pictures tell, but the first one is a case fired of the 35.5gr load and the second the 37gr load. The prints is not very shiny, but just like a just noticeable "ring".

The print goes from between the "4" and "7", to between the "L" and "A"

Here the print goes from between the "U" and "A" and out in the space between the "A" and the LAPUA logo.
http://eb9eza.bay.livefilestore.com...JYg8C82Yf465RpgoViMsaacsLh7IqbYG/DSC_0027.JPG

Not all of the cases got "printed", but i would say 50%. The bullet, a scenar 123 was slightly jammed in the rifling and the powder used was N-150.

I think it would be odd if the low load would be to hot.

 

[Burras]

And one thing more. The circular scrape marks around the bottom, is from the primer pocket uniformer. I did not get any circular grind marks from the bolt.

 

[Boyd Allen]

The cleaning of the barrel between shots is the reason for the ejector printing. You are not getting the chamber fully dried after cleaning. A friend had this problem with a 6BR. With his normal warm, but not too hot loads, he would get an ejector print for the first shot or two after cleaning. It turned out to be because he was reusing a chamber swab that was contaminated with cleaning solvent from previous uses.

Try this; finish your cleaning by using alcohol on the chamber, applied with an oversized patch, and then drying with a strip of paper towel wrapped around a bore brush so that it is larger than the chamber and extends past the front of the brush, sort of a cone shape that is bigger than the chamber. Shove it forward in the chamber and twist back and forth. Do this last part twice, rewraping the paper towel strip to expose clean paper the second time. Let us know how this works for you.

 

[Burras]

Thank you. I really weren't that careful with always using a really clean paper towel. I normaly only use paper towels when cleaning the chamber and no alkohol, but I will try this.

IF the marks are due to a dirty chamber, is it because the case can't grip the chamber walls properly and all the stress goes straight back in the casehead?

 

[alinwa]

Did you weigh EACH charge or just weigh to set your powder measure? When running close to the edge you MUST weigh each load, just throwing from the measure guarantees over-charges.

al

 

[Burras]

Yes I weighted the charges. And if I had not, the lower charges should not be on the limit

 

[Don]

I wonder if a hint of ejection mark ALWAYS means that you got to high pressure?

I started a break in of a new barrel in 6.5x47 Lapua and shot loads, 3 by 3 from 35.5-37gr. Since it was a break in I obviously cleaned the barrel between the shots and got no signs of heavy boltlift through the ladder. The velocity during the loads did not seem to flatten out.

I don't know if the pictures tell, but the first one is a case fired of the 35.5gr load and the second the 37gr load. The prints is not very shiny, but just like a just noticeable "ring".

The print goes from between the "4" and "7", to between the "L" and "A"

Here the print goes from between the "U" and "A" and out in the space between the "A" and the LAPUA logo.
http://eb9eza.bay.livefilestore.com...JYg8C82Yf465RpgoViMsaacsLh7IqbYG/DSC_0027.JPG

Not all of the cases got "printed", but i would say 50%. The bullet, a scenar 123 was slightly jammed in the rifling and the powder used was N-150.

I think it would be odd if the low load would be to hot.

I dont see any ejector marks that you describe in the photos taken, probably because the camera focused on the one shell that you had raised, which only appears to have an extractor ding on the base edge.

The one thing that does show in the photos, even with the remaining lowered shell cases in the box that are slightly out of focus, is that many of the fired primers are considerably flattened and have alot less rounded radius edge than the unfired primers...............which is always a possible indication of high pressures regardless of the charge thrown compared to published load/pressure data. This may indicate that you have a very tight bore and that your perceived moderate loads are indeed creating much higher pressures than anticipated.....................Don

 

[Boyd Allen]

Its a grip thing. The residual solvent acts as a lubricant. I use a fresh piece of paper towel each time.

 

[John Kielly]

Hope I'm not missing something here, but what I see is a drag mark that likely occurred during bold lift until the primary extraction "cam" locked the extractor onto the rim & pulled the case. That suggests to me that the ejector is sitting proud of the bolt face & its edge is scraping off the softer brass.

Try giving the bolt a good wash in solvent or dismantle the ejector plunger & check out everything for crud or shavings.

 

[Burras]

Ok, many leads to follow up here. I will start with cleaning the chamber throughly from solvents and such, and clean the bolthead. I hope I will find something out from this.

 

[243winxb]

Replace the ejector spring?

Maybe replacing the ejector spring might make a difference. If the one in there now has been trimmed, making it lighter, to not throw the case fully out of the action.

 

[alinwa]

Maybe replacing the ejector spring might make a difference. If the one in there now has been trimmed, making it lighter, to not throw the case fully out of the action.

What might this do 243winxb??? I can't see the gain in countering 65,000 pounds with a fraction of a pound. What am I missing here?

al

 

[Burras]

Maybe replacing the ejector spring might make a difference. If the one in there now has been trimmed, making it lighter, to not throw the case fully out of the action.

The thing is that the ejector spring HAS been replaced with a lighter one, but I don't see either what difference it would make. Never heard about it either.

 

[243winxb]

i did say "maybe"

 

[Burras]

I recently came back from the range with some other tests. Now the components where Norma 130gr VLD and Norma 203-B.
I wanted to see if the reults where any different about the marks in the bottom of the case and look for tendencies in precision (which where promising all over the ladder). Now I got tendencies to marks from the lowest load (33gr) and to the highest (36,5gr). No extra resistance in bolt lift or other unusual observations that i could notice. This puzzles me since we are talking about pretty low loads for this powder (similar burnrate as N140 and RL15). And yeah, I cleaned the chamber and wiped the cases throughly from lube and dirt.
What do you think? Can there be other reasons than pressure.

 

[Burras]

Since this is brand new brass we are talking about, I was wondering if maybe excess headspace can give extractor marks?

 

[Don]

Since this is brand new brass we are talking about, I was wondering if maybe excess headspace can give extractor marks?

No, excess headspace can do funny things to primers but not the ejector/case base interface................Don

 

[John Kielly]

Don,

I've found from sad experience that when more than desirable headspace occurs, funny things happen with the base of cases - as I found to my disadvantage when I oversized some cases for a refreshed barrel that wouldn't chamber the old brass any more. Turned out that the new neck was just enough thou tighter (not a turned neck chamber) so the old fired necks wouldn't enter 'em. Anyway, the result was when I fired a few of those buggers, they rivetted back to the bolt face & made the primers look more than a tad overload.

Anyway, in Burras' case, just say his ejector is a bit short, a bit worn when something like happened to me comes along, then maybe there's enough going on there either for the case to take a mark from the ejector or the ejector to bounce when all this is going on & tap a brand on the case.

Maybe.

John

 

[Stonewall]

Measure the case with a shoulder gauge before and after firing.
Make sure that you don't push the shoulder back more than .002 .


I saw a .30-378 Weatherby that would do this with the light loads in new brass every time. The problem was that the case got a running start to the bolt face because the case shoulder had to fire form .008 to fit that chamber.


Glenn

 

[Burras]

Measure the case with a shoulder gauge before and after firing.
Make sure that you don't push the shoulder back more than .002 .


I saw a .30-378 Weatherby that would do this with the light loads in new brass every time. The problem was that the case got a running start to the bolt face because the case shoulder had to fire form .008 to fit that chamber.


Glenn

Actually I measured on the shoulder with a guage. Brand new cases - and fired one time cases. It was an overall difference of .0047" between the new and fired cases. Maybe that could mean something?