Extractor Mark w/ Cold, Clean Bore

[bill123]

I'm using the following .308 hand load:
Lapua brass, neck turned to .014", OAL: 2.007"
BR-2 primers
46.5 grains Varget
Berger 155.5gr Fullbore

I have never had pressure signs from this load in roughly 300 rounds and loaded it as high as 46.8 grains.

My Bartlein barrel has 3,850 rounds through it. Still shoots 3/8" groups when I'm paying attention. I just cleaned with Wipe-Out overnight, ran 2 patches through it and brought it to the range to shoot 30 rounds.

After shooting the 1st 5 round group, I noticed extractor marks on 3 cases. I'm assuming that it was the 1st 3 cases. One is a pretty hard mark and the marks diminish from there. The rest of the 27 cases that I shot have no marks or any other pressure signs that I can see. Did I simply not get all of the cleaning solution out?

Aside from being one of the better groups or the session, the cold, clean bore group is unremarkable. 3/8" and same POI as the rest of the groups.

 

[gohring3006]

if it got better after the first three I would say your right about the cleaning solution/oil if you you used oil

 

[bill123]

if it got better after the first three I would say your right about the cleaning solution/oil if you you used oil

Thanks.

 

[RockZ]

it's probably the best you've ever cleaned the barrel...down to bare metal.
a squeaky clean barrel creates a lot more friction and higher pressures

 

[EddieHarren]

Extractor or Ejector marks? What action?

 

[bill123]

Extractor or Ejector marks? What action?

Templar action (rem. 700 type). You're right, ejector, it's the half circle on the base of the case mark. Looks like a smile.

 

[bill123]

it's probably the best you've ever cleaned the barrel...down to bare metal.
a squeaky clean barrel creates a lot more friction and higher pressures

Maybe after using wipe out I should run an oily patch followed by a dry patch through before shooting? I'm surprised that the group was so tight and no POI shift with an increase in pressure.

 

[RockZ]

I know some bench rest shooters that put a patch of lock-eze through the barrel before shooting.
It's a graphite in alcohol solution ...coats barrel with a dry lubricating film.
Not sure if graphite,heat,and metal bullet jackets cause any bad reactions in the barrel, but they say it works great.
I would definitely put a patch with oil or whatever bore conditioner you have after using wipeout.
Than dry patch before shooting.

 

[bill123]

I know some bench rest shooters that put a patch of lock-eze through the barrel before shooting.
It's a graphite in alcohol solution ...coats barrel with a dry lubricating film.
Not sure if graphite,heat,and metal bullet jackets cause any bad reactions in the barrel, but they say it works great.
I would definitely put a patch with oil or whatever bore conditioner you have after using wipeout.
Than dry patch before shooting.

I'm thinking its a slightly different problem now. I was shooting yesterday in the rain. I started out with my hand loads and got the pressure signs. I switched to Federal 175 grain match ammo and I got the ejector marks on the case bases of that ammo when the barrel was hot. After I let the barrel cool, the marks disappeared until the barrel heated up again. The barrel was never too hot to touch, just hotter than I normally let it get.

I'm thinking that the problem may have been that I did not get all of the Imperial Sizing Wax off the cases and they were not able to grip the chamber during ignition, forcing them back into the bolt harder than usual. Maybe the wax collected in the chamber and caused the same problem with the Fed. ammo. Does that make any sense?

 

[Canadian Bushman]

That makes sense

Anytime you reduce friction between the case and the chamber walls you will see an increase in pressure signs on the head of the case. Since the walls are no longer holding the case with the same grip as they normally would, the rearward pressure increases.

I know varget is very temp stable but letting a cartridge dwell in a hot chamber during a string can also cause an increase in pressure. I lay the next round on the mag follower and chamber it when ready to fire.

 

[brentc]

Don't know if this has been stated already, but if you don't ensure that all oil is removed from the chamber prior to your first shot from a freshly cleaned barrel it will show pressure signs.

 

[bill123]

Thanks to all for your help!