Carbon soot going back past shoulder?

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Carbon soot going back past shoulder?

Post by Cooper » 24 Jan 2018, 9:41 am

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Trying to work up a 95gr vmax load in my 6.5 Creedmoor. Started with 38gr of Ar2206H. Brass is Hornady which has been full length sized and tumbled clean in stainless steel pin media tumbler so we're nice and shiny.

I fire 3 round at 38gr ar2206H and noticed abit of soot going back past the shoulder. Which I don't normally see... read that problem might be that powder might be a bit slow.

Tried Benchmark 8208 at 38.5gr and first case looked normal. Second case had a bit of carbon soot going back the length of case and even a bit of carbon around rim? 3rd case had a bit of carbon back past the shoulder like the AR2206H loads.

Thinking I'll try increasing the loads abit and maybe the problem will go away one brass is fire formed?

Maybe the Lee Full length die has undersized the cases???

Dunno?

Happy for any input. Thanks
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Re: Carbon soot going back past shoulder?

Post by hazza3006 » 24 Jan 2018, 10:58 am

yeah, i've got a 6.5x55 and starting with FLR of new lapua brass, then just neck sizing and case trimming thereafter,and only ever used near starting loads of 46grn of slow burning AR2209 with the 95grn vmax projectile, and whilst don't have carbon soot marks past the shoulder like you, my now used lapua brass, some of the cases still not fully fire-formed. The CCI primers are also showing very rounded edges too, no signs of pressure at all.

My next step will be to start increasing loads from starting, and hence increasing chamber pressure, hopefully will complete the fire-forming process.
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Re: Carbon soot going back past shoulder?

Post by brett1868 » 24 Jan 2018, 11:53 am

Loads are in the middle of the range for that combination of powder / projectile which is a good start. What's the neck wall thickness? as it looks to have been neck turned. Any chance of a picture showing how the primers look? I suspect the neck is a bit undersized in the chamber and not expanding fast enough to seal. Can you measure the neck of a fired case and again after sizing please.
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Re: Carbon soot going back past shoulder?

Post by hazza3006 » 24 Jan 2018, 12:01 pm

brett1868 wrote:Loads are in the middle of the range for that combination of powder / projectile.


his 38grn AR2206H loads are only 1 grn above starting loads for 6.5 creedmoor with 95 grn vmax projectile, max load is 41grn, so he's much closer to starting loads.
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Re: Carbon soot going back past shoulder?

Post by brett1868 » 24 Jan 2018, 12:15 pm

hharry06@gmail.com wrote:
brett1868 wrote:Loads are in the middle of the range for that combination of powder / projectile.


his 38grn AR2206H loads are only 1 grn above starting loads for 6.5 creedmoor with 95 grn vmax projectile, max load is 41grn, so he's much closer to starting loads.


Yep, my bad. I was looking at the 8208 data...still more then likely a combination of light loads and neck size.
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Re: Carbon soot going back past shoulder?

Post by Cooper » 24 Jan 2018, 12:22 pm

Necks not turned. But after full length sizing I did put the them all through my neck bushing die with .289 bush. So that explains marks on neck.

I'll try just Lee Collet sizing the next batch. But whatever reason the necks are not expanding to the chamber with 95gr Vmax.?? Size after firing is like .290 still looks and feels like I could seat another projectile without neck sizing?

I checked my Lapua case which have expanded to .295 fired 143eldx and some other Hornady case which I fired 140gr projectiles and they have expanded to .294/.295

The Hornady brass is on its 4th firing. I'm thinking that now brass is fire firmed slightly. The neck might expand properly on the next firing? Maybe the Hornady brass is a bit stiff (might need necks annealed?)

Thanks for suggesting to measure the necks Brett. I was just thinking it was just a powder to projectile choice problem.
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Re: Carbon soot going back past shoulder?

Post by Cooper » 24 Jan 2018, 12:25 pm

I'll also work my way up to max loads. I have 8208 so I'll try that. Might be a bit faster that Ar2206h. I also have a 26inch barrel.
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Re: Carbon soot going back past shoulder?

Post by Mitch » 24 Jan 2018, 1:00 pm

Try a powder like 2208 or 2209.
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Re: Carbon soot going back past shoulder?

Post by ebr love » 24 Jan 2018, 5:58 pm

Cooper wrote:Maybe the Lee Full length die has undersized the cases???


What rifle are you using?

Thinking about chamber size relative to the FL sized cases here.

A chamber cut on the more generous side of the tolerances perhaps, compared to the die.
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Re: Carbon soot going back past shoulder?

Post by Cooper » 24 Jan 2018, 8:38 pm

Factory Howa 1500 with 26 inch barrel. I also think it has more to do with the full die and or chamber size. When I first got the rifle I tried several loads down near the minimum charge with AR2208 (new factory Hornady brass). I only full sized the brass because I had a few stiff bolt lifts using max charges of Ar2209 and wanted to start from scratch. I have switched to Lapua brass now for my ar2209 loads with 143 ELD-x. But just wanted to work up a 95gr Vmax hunting load using the Hornady brass.
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Re: Carbon soot going back past shoulder?

Post by Strikey » 24 Jan 2018, 9:08 pm

Soot down around the neck/ shoulder is usually a good indication of a too light load for that particular combination, personally think you might do better with 2208 :thumbsup:
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Re: Carbon soot going back past shoulder?

Post by Apollo » 24 Jan 2018, 11:00 pm

Well, to me I can't see any Carbon Soot at all. What I can see is dirt on the case or left over lube that's been overheated.

The photo's are from the wrong angle. Carbon soot starts at the neck and after been freshly fired will wipe off.
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Re: Carbon soot going back past shoulder?

Post by Cooper » 25 Jan 2018, 9:37 am

Strikey wrote:Soot down around the neck/ shoulder is usually a good indication of a too light load for that particular combination, personally think you might do better with 2208 :thumbsup:


Yeah I reckon I'll try ar2208. Will work my way up near maximum. Thanks
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Re: Carbon soot going back past shoulder?

Post by Cooper » 25 Jan 2018, 9:44 am

Apollo wrote:Well, to me I can't see any Carbon Soot at all. What I can see is dirt on the case or left over lube that's been overheated.

The photo's are from the wrong angle. Carbon soot starts at the neck and after been freshly fired will wipe off.


I think I'll clean my chamber. But I think you might be right about case lube. I've just stared using Imperial wax. But I have been using hardly any. Just a little bit on neck when using bushing die. Looks like somehow I've got some (more that I thought) left on the case. The stuff on the case did look a greasy. My bad. Thanks
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Re: Carbon soot going back past shoulder?

Post by marksman » 25 Jan 2018, 12:01 pm

usually carbon down the neck or lower is because of a light load with thick necks,
the neck is not expanding quick enough and the gases/flames are getting under the neck before the case fits the chamber
as you increase the load the carbon will rise up the neck
its not a good thing to have it down past the shoulder especially if you get deformed bumps in the case, can be dangerous
just put in more powder and see it go away :thumbsup:
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