Why are these Flat Spots on my Shoulders

[mgunderson]

How much are we sizing the brass? I like the plugged vent hole observation. Looks we are setting the shoulder back based on how crisp the corners look.

Heavy bullets and high pressure or light bullets?

Bushing die, factory one piece die, or custom honed sizing die?

 

[RED DIRT]

Might be a bit anal, but i clean my resizing dies after every use. Always make sure you clean out the air bleed hole in the die. It doesn`t take long for debris to start building up and plugging that tiny little air bleed hole. That is usually the culprit leading to oil dents in your brass. Lube goes a long ways, too. You don`t need as much lube as you think you do.

 

[rwj]

All good suggestions made in this thread! I practice most of them and have experienced the same issue as @hoz53 with only Peterson 6BR brass. Interesting in that it has only occurred on just one lot of the many I have in service. Perhaps it’s lot dependent and related to the manufacturing process?

 

[RED DIRT]

All good suggestions made in this thread! I practice most of them and have experienced the same issue as @hoz53 with only Peterson 6BR brass. Interesting in that it has only occurred on just one lot of the many I have in service. Perhaps it’s lot dependent and related to the manufacturing process?

You got a bad "lot" batch. It happens.

 

[hoz53]

Since it appears to go all the way around the case shoulder I'd say you have some chatter from the chambering reamer. How old is the chamber?

thats an interesting thought. its about a year old. the dents wernt there after firing though only after sizing. and i didnt get the dents on lapua . still its something i will check out. Its time to rechamber/rebarrel this one anyway. thanks.

 

[RED DIRT]

thats an interesting thought. its about a year old. the dents wernt there after firing though only after sizing. and i didnt get the dents on lapua . still its something i will check out. Its time to rechamber/rebarrel this one anyway. thanks.

I`m not sure of the brand of brass your using, likely thinner than Lapua (?)

Just something to ponder.

 

[hoz53]

You got a bad "lot" batch. It happens.

very well could be as Im generally the one that gets the Bad batch. It sure has shot good though. i cannot kick on that. quite a few rounds on this brass to and so its about that time anyway. in a way these flat spots are kind of an extra gift pushing me to learn something and figure this out. thanks

and on the brass being thinner I will cut one of each and check that out and post a pic thanks again

 

[RED DIRT]

very well could be as Im generally the one that gets the Bad batch. It sure has shot good though. i cannot kick on that. quite a few rounds on this brass to and so its about that time anyway. in a way these flat spots are kind of an extra gift pushing me to learn something and figure this out. thanks

and on the brass being thinner I will cut one of each and check that out and post a pic thanks again

You responded at my comment to the other member "rwj" post #24 & #25

 

[hoz53]

How much are we sizing the brass? I like the plugged vent hole observation. Looks we are setting the shoulder back based on how crisp the corners look.

Heavy bullets and high pressure or light bullets?

Bushing die, factory one piece die, or custom honed sizing die?

about 002 bump. — ill check that some more.

6BR—- 105s—-30 gr N150—2840 ish

redding S die bushing die with redding steel bushing-

thanks

 

[hoz53]

You responded at my comment to the other member "rwj" post #24 & #25

sorry about that

 

[RED DIRT]

sorry about that

Not a problem at all my friend.

 

[K22]

Not familiar with the die that you are using but when I have seen those type of dents, they have always been a lube issue on the shoulder. That's not to say that is necessarily the cause here but that's been my observation.

For what you posted, this condition only occurs when you attempt to size these cases. Obviously, something is going sideways with your sizing operation. I can only think of three issues that may cause this: (1) lube on the shoulder or accumulated in the die, (2) air compressed and trapped in the die deforming the case, (3) excessive pressure on the cases due to over sizing aggravated by this brand of cases being of a different thickness than the Lapua.

If possible, I would try a standard die or different sizing die on three or five cases.

- Are you getting a lot of resistance when you size these cases? In other words, having to apply significantly more pressure than with the Lapua cases?

- Do you measure fired and sized case head space with a bump gauge and caliper and if so, are you getting several thousandths expansion. In other words, do you have to bump the shoulder?

- As I said, I am not familiar with bushing dies, never used them but is it possible that you are using an inappropriate bushing creating too much stress on the case?

 

[hoz53]

Not familiar with the die that you are using but when I have seen those type of dents, they have always been a lube issue on the shoulder. That's not to say that is necessarily the cause here but that's been my observation.

For what you posted, this condition only occurs when you attempt to size these cases. Obviously, something is going sideways with your sizing operation. I can only think of three issues that may cause this: (1) lube on the shoulder or accumulated in the die, (2) air compressed and trapped in the die deforming the case, (3) excessive pressure on the cases due to over sizing aggravated by this brand of cases being of a different thickness than the Lapua.

If possible, I would try a standard die or different sizing die on three or five cases.

- Are you getting a lot of resistance when you size these cases? In other words, having to apply significantly more pressure than with the Lapua cases?

- Do you measure fired and sized case head space with a bump gauge and caliper and if so, are you getting several thousandths expansion. In other words, do you have to bump the shoulder?

- As I said, I am not familiar with bushing dies, never used them but is it possible that you are using an inappropriate bushing creating too much stress on the case?

Hi K22. all the dents i have seen in shoulders have been a lube issue also. i worked with this again today. it seems i was over sizing the cases by mabie 002 as after i cleaned the die again and sized with just a lite amount of imperial on the body and the imperial neck lube dipping the necks the bump wasnt as much. cases look much better but i believe there are still small dents. i do have another of these dies i can try. i do use a sinclair bump gage. i get less resistance from the lapua. oh i do have the correct bushing in the die. i have some other pete brass i think i will try- same lot- the original batch is almost all sized now so i gotta shoot them to experiment some more. Im really wondering now if i have some chatter marks in chamber. gotta take new batteries for hawkeye tomorrow.
thanks

 

[hoz53]

I`m not sure of the brand of brass your using, likely thinner than Lapua (?)

Just something to ponder.

i did grind a few cases today— they look and measure about same to me thanks

 

[hoz53]

thats an interesting thought. its about a year old. the dents wernt there after firing though only after sizing. and i didnt get the dents on lapua . still its something i will check out. Its time to rechamber/rebarrel this one anyway. thanks.

got the hawkeye out today to try to check the chamber. didnt get to far as it needs batts and i need to clean a little more. i did get the sized brass looking better but dont know i got the problem fixed. will report more tomorrow. thanks—- stripes but i dont think a dent

 

[hoz53]

All good suggestions made in this thread! I practice most of them and have experienced the same issue as @hoz53 with only Peterson 6BR brass. Interesting in that it has only occurred on just one lot of the many I have in service. Perhaps it’s lot dependent and related to the manufacturing process?

its interesting someone else sees this. worked on this today but didnt completely get the dents to disappear. i think i will anneal them and see what happens. seems i recently did that but mite as well try again. thanks

 

[hoz53]

Hoz

Does your die have a hole drilled into to it, 90* to the chamber ?
It might be plugged. Take a paper clip and clean it out.
Sometimes it’s hidden under the lock ring that’s used to adjust the die height.

Hal

i looked that die over today thoroughly and coukdnt find a hole— did find them in some forester. couldnt find a hole in any redding— i think i will call them and see wat they say.
thanks Hal

 

[hoz53]

From personal experience that looks exactly like some case shoulder dents that I had on some 6BR brass and it was a particle of un-burnt powder compressed and stuck to the chamber.
You notice that the dent has soft outline, indicating that the thing that caused the dent is not hard like a piece of brass or grit but under high compression when the case is fired solid enough to imprint the brass of the neck.
I would have a look with a bore scope but even without a look, get an AR chamber brush and give the chamber a real good scrub and see if that fixes it.
I did not notice the dents while shooting but only after the brass was cleaned and only as I was sizing and wiping the lube off the case did I see it...

im working on it— at first i thought i didnt have dents before sizing but today it appears i did. gonna clean the gun more and borescope tomorrow and will report back. thanks

 

[hoz53]

In my experience you don't need to lube the shoulder for normal sizing. I roll mine on an old RCBS lube pad. Maybe hit the neck with the crazy cloth to remove the carbon, and done. Hit that die with some brake cleaner. Go slow on the first few cases as it will be squeaky clean. Good luck.
Paul

i did the brake cleaner today. seems better but i dont know if im there yet. thanks paul

 

[hoz53]

My first thought would be to clean the die. However, I have had Redding dies do this with very tight formed brass because there was no vent hole and the case and wax seal so tightly it dents the shoulder. This was the reason I stopped using Imperial and went to Royal which solved my problem. Haven't had a dented case since. If your die has a vent like Hal mentioned then it is likely plugged.

i looked over some reddings today and none of them had vent holes i could find. i cleaned the die to and i think it helped a little. sure couldnt see anything in there though. ill get some of that royal you recommend and see what happens—- thanks