Carbon on shoulder Dasher

[Raufoss]

I have a tricky question and I hope that someone experienced the same thing.

So with my Dasher , firing virgin ALPHA brass , they come out pristine with little to no carbon on the necks.....but with once fired FL sized brass there is carbon on the shoulder and neck....

There is no difference in accuraccy.

I use a Forster custom ALpha honed FL sizing die with a Sinclair expander as a seperate operation. Shoulder are only bumped 0.002''( yes I am 100% sure).

Powder: N150
Primer: CCI-450
Case: Alpha ( non OCD)
Bullet: 109gr Berger
Speed: 2815 fps

Have anyone experienced that? What could be the cause?

 

[Mordamer]

Probably has to do with the necks on virgin brass being softer and creating a better seal against the chamber neck. Second firing the necks are harder and don't seal up as good.

If they shoot good just clean them and move on with life.

 

[Raufoss]

Probably has to do with the necks on virgin brass being softer and creating a better seal against the chamber neck. Second firing the necks are harder and don't seal up as good.

If they shoot good just clean them and move on with life.

Roger.

With your Forster you don't have the same results than me or since you may anneal every time you don’t see that?

 

[XLR308]

Exact same load only difference is once fired brass ?
I have had sililar issue but not with 6 Dasher, slightly upping the charge fixed it in my case.
Possibly slightly lower pressures due to case being formed versus new first firing.

 

[Raufoss]

Exact same load only difference is once fired brass ?
I have had sililar issue but not with 6 Dasher, slightly upping the charge fixed it in my case.
Possibly slightly lower pressures due to case being formed versus new first firing.

Exact same load between new and sized and exact same speed too.

I even tried a slightly higher charge but still the same results and it’s not as accurate .

 

[XLR308]

Exact same load between new and sized and exact same speed too.

I even tried an higher charge but still the same results and it’s not as accurate .

Got it, mine was with Lapua Palma 308win but once i upped the charge the issue disappeared. Im sure the Dasher chambers are much closer match in most cases than a factory 308win chamber.
Have you tried any other powders with a touch fasterr burn rate ?

 

[Mordamer]

Roger.

With your Forster you don't have the same results than me or since you may anneal every time you don’t see that?

I do anneal every time and I generally don't see much carbon buildup on the necks or shoulders. I do see a slight increase in carbon on the necks and shoulders every firing. It could be carbon buildup in the chamber neck preventing a perfect seal from the brass.

 

[Raufoss]

Got it, mine was with Lapua Palma 308win but once i upped the charge the issue disappeared. Im sure the Dasher chambers are much closer match in most cases than a factory 308win chamber.
Have you tried any other powders with a touch fasterr burn rate ?

I’m running N150 because I can’t find anything like Varget where I’m at.

I think I can find 4166 locally .

 

[XLR308]

I’m running N150 because I can’t find anything like Varget where I’m at.

I think I can find 4166 locally .

I kind of figured that, like was allreay said if it shoots to the level of precision you require roll with it.

 

[spife7980]

If its shooting accurately and not sooting down on the base of the case demonstrating leakage I wouldnt care what they look like. Throw it in a tumbler after if youre worried about it.

But like Mordamer said, it gets worse every firing.

 

[John Glidewell]

This might be something to do with Vihtavuori powders. I am running a bunch of them and they all do that, very light carbon deposit on shoulder, otherwise very clean necks and cases, just light carbon on shoulder. All running great, but I did notice that this weekend testing N165 in 6.5 creed and 144 bergers.

 

[Milo 2.5]

I had this happen with 3 of 4 Dashers I had a couple yrs ago. Did it with Varget, H4895, and RL 16. I attributed mine to a tapered neck reamer.
I just quit sizing the necks all the way more or less creating a goiter at the base of the neck. Worked for me, but I never had planned on more than 8 firings from my brass. You do this, and want 20 firings, at some point I believe it will bite, and something will need to be done.

 

[John Glidewell]

Alpha OCD brass in custom chamber, required neck turning. Very light on shoulder, the funky chatter is just carbon swipe from opening bolt.

 

[Raufoss]

If its shooting accurately and not sooting down on the base of the case demonstrating leakage I wouldnt care what they look like. Throw it in a tumbler after if youre worried about it.

But like Mordamer said, it gets worse every firing.

That’s what I’ll do and probably get another powder.

This might be something to do with Vihtavuori powders. I am running a bunch of them and they all do that, very light carbon deposit on shoulder, otherwise very clean necks and cases, just light carbon on shoulder. All running great, but I did notice that this weekend testing N165 in 6.5 creed and 144 bergers.

Maybe . I’ll try some 4166 to see if it make any difference.

I had this happen with 3 of 4 Dashers I had a couple yrs ago. Did it with Varget, H4895, and RL 16. I attributed mine to a tapered neck reamer.
I just quit sizing the necks all the way more or less creating a goiter at the base of the neck. Worked for me, but I never had planned on more than 8 firings from my brass. You do this, and want 20 firings, at some point I believe it will bite, and something will need to be done.

I made sure with my reamer design to have a straight neck no taper. But yes your right that maybe I’d have an issue trying to get long life brass. It’s not my goal and I have like 500 of OCD brass so 8 firing is 4K round I’d be happy with that.

Alpha OCD brass in custom chamber, required neck turning. Very light on shoulder, the funky chatter is just carbon swipe from opening bolt.
View attachment 7652842

Interesting. Why neck turning would help? More flexibility for sealing?

 

[John Glidewell]

Interesting. Why neck turning would help? More flexibility for sealing?

I had to turn necks because it is a custom chamber (tight) and required neck turning, has nothing to do with your situation. I mentioned it only because it could be I took a little more than needed and it is not sealing right away. If you do not have a tight chamber then there is no real reason to turn necks.

 

[Dthomas3523]

I had to turn necks because it is a custom chamber (tight) and required neck turning, has nothing to do with your situation. I mentioned it only because it could be I took a little more than needed and it is not sealing right away. If you do not have a tight chamber then there is no real reason to turn necks.

Tight chambers should be a result of neck turning, not the other way around.

Neck uniforming has its own pros/cons. And you get a tighter neck reamer when you want your neck clearance to be less than it would be in a no turn reamer with turned necks (debatable if excessive clearance really matters).

If you’re turning necks because of a reamer, then you have the wrong reamer spec for your brass.