Sooty cases

[No i deer]

I started shooting a COF at 600yds this afternoon with my 6.5x47 and cases started coming out sooty....

Load was 

Lapua brass, Br4s, 140gr amaxs over 41.5grs of RS62. It was 2,120 comparator measure jumping 20 thousanths 

brass was on its second firing a after annealing.

It didn't seem affect it's Accuracy.

Just out of curiosity I swapped the moderator for a muzzle brake to see If there was any difference in accuracy and if anything it was slightly better with the brake and the soot that went all down around the cases had stopped and gone back to being a little sooty around the necks only....🤔

I have used this load before and it didn't do it......

I was wondering if some debris or a few rain drops my have got on the brass which then found itself in the chamber which stopped it sealing the chamber on the ignition of the powder....

I wouldn't of thought the swapping of mod too the brake made any difference or would it.....???

[One on top of two]

I have had similar with my creedmoor, it’s was almost like a smokey effect down the cases , like you it’s a very well used and tested load buy myself. 
I did notice the case sometimes times felt what I can only describe as damp ? 
which I put down to cold ambient air temp and a warm chamber . 
anyway it’s only happened once . 
rightly or wrongly that’s what I put it down to. 
also like yourself accuracy was not effected . 
 

it’s just a shooting  El Niño effect.

[No i deer]

Yeah Smokey would describe it and handling them it came strait off on my fingers/hand.

We're you happen to be using RS62.

All my 6.5x47 brass is now freshly annealed ready for firing again.

Today's brass will prepped and re-annealed.

[henryo]

I wouldn't know but is it quite a mild load / slow powder? Sometimes too low a pressure will not make the case obturate fully in the chamber.

Re. moderators they are known to create 'back pressure'. Not normally an issue with bolt guns but the Americans have to worry about it with their autos.

Maybe also check for oil in the chamber as it needs to be dry for the brass to 'stick'.

Would be interesting to know if your loads were neck sized only as it should be a close tolerance fit and you wouldn't expect these problems.

H

[Catch-22]

So you’re saying cases were more sooty with the moderator, less sooty with the brake?

That makes sense because the moderator overgasses it a bit. After the shot, some powder residue would flow back into the barrel and the chamber as the gasses in the moderator slowly dissipate. As the brass has already sprung back from the chamber walls, any gas floating back down the barrel from the moddy will make the entire case sooty, not just the neck.

 

[No i deer]

10 minutes ago, henryo said:

I wouldn't know but is it quite a mild load / slow powder? Sometimes too low a pressure will not make the case obturate fully in the chamber.

Re. moderators they are known to create 'back pressure'. Not normally an issue with bolt guns but the Americans have to worry about it with their autos.

Maybe also check for oil in the chamber as it needs to be dry for the brass to 'stick'.

Would be interesting to know if your loads were neck sized only as it should be a close tolerance fit and you wouldn't expect these problems.

H

All my brass gets full length sizing.

It's a slightly compressed load and definately not mild....

Powder comes to bottom of the neck and the bottom of the bullet must be down near the shoulder body junction.

I use 41grs with a 139gr scenar as they seat quite deep.

42grs behind the 140gr amaxs may see pressure signs and would be a well compressed load.

I wouldn't want to go there.....

[One on top of two]

Surely the case would have sealed the chamber neck  enough to stop gases from getting Back into chamber , also the spent case would in most cases be ejected from chamber in seconds ? 

[No i deer]

27 minutes ago, Catch-22 said:

So you’re saying cases were more sooty with the moderator, less sooty with the brake?

That makes sense because the moderator overgasses it a bit. After the shot, some powder residue would flow back into the barrel and the chamber as the gasses in the moderator slowly dissipate. As the brass has already sprung back from the chamber walls, any gas floating back down the barrel from the moddy will make the entire case sooty, not just the neck.

 

Maybe your right catch...

Only thing I'm not sure of its 600yds snaps and I am firing 4 shots in around 25 seconds and the cases are ejected instantly....

I did notice smoke coming out behind the ejected case though 🤔👍

[Catch-22]

It all happens in a fraction of a second. The moddy overgasses the barrel, forcing a back pressure as already noted. 

Bet you if you shoot the same load with brake or nothing on the end, you won’t have any sooty cases, other than the ‘sine-wave’ on the necks. With the moddy, you’ll continue getting the sooty cases.

If you’ve had the moddy a while but this is the first time it’s started doing this, it could be your mod needs an internal clean, especially around the initial blast chamber and first set of baffles. Maybe there’s a buildup of carbon in there which is aiding the over-gassing??

[One on top of two]

3 minutes ago, Catch-22 said:

It all happens in a fraction of a second. The moddy overgasses the barrel, forcing a back pressure as already noted. 

Bet you if you shoot the same load with brake or nothing on the end, you won’t have any sooty cases, other than the ‘sine-wave’ on the necks. With the moddy, you’ll continue getting the sooty cases.

If you’ve had the moddy a while but this is the first time it’s started doing this, it could be your mod needs an internal clean, especially around the initial blast chamber and first set of baffles. Maybe there’s a buildup of carbon in there which is aiding the over-gassing??

Yes will go with that , to be honest at the time I didn’t think much to it. Certainly not a cause for concern. 

[No i deer]

As I said I've used this load before BUT only firing the odd shot hunting or a little ammo/group test with the mod on....

I've used that load at Bisley before but with a muzzle brake on....

Yesterday was the first time I've ever used a mod on it at a range ie.  Reason being was i developed the load with the mod on so I thought it best to use it with it on....

Before this I've  always used a muzzle brake at Bisley...

My mod is a jetz compact I think... It's a jetz of some form.

Also today I used my the Mk1 S5 ase ultra on my 26 inch 284 hunter in the morning at 900 and 1000yds and I didn't have a problem with this........ normally I use a brake on this too....

Reason being back a several months ago I used my 284 hunting rifle in a f open match as my 7mm saum was away being rebarreled.

Prior to this match I tried it with a bare barrel ready for the match and it was horrible too shoot bouncing around being only about 12lb naked, I took a chance and stuck the mod for the match which tamed it down nicely and to my surprise accuracy was real good as it shot about 3/8ths elevation at 600yds.

Muzzle brakes are not allowed in F class otherwise I would of used it...

Thanks for your help chaps worry over 😅👍

Atb No I deer