Soot right down the case

jackfish

Well-Known Member
Wondering if anyone can help, I'm shooting 6.5x55 with 120g BT's and N160 averaging 2500 ft/s through the chrony. I'm getting quite a lot of soot down the cases, cases are full length resized and trimmed as per usual spec, the load is very very accurate. Just seems to be that since using the N160 cases are very dirty. Anyone else had this issue?
Cheers
Bryan
 
I've had the same with full length resized cases. This is most likely to do with excessive headspace.

Screw your fl die out a bit until your cartridges chamber a bit more snugly. You want to feel a little resistance upon closing the bolt.

Neck sizing cases that have been fired in your rifle will also solve the problem.

A light load may also be partly to blame - stoking it up a bit will help the case to seal better before the gas gets a chance to blow down the outside of the case.
 
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Cartridge cases are the 'seal' for the chamber. If there is not enough pressure, the seal will not be complete. I don't know what your charge is but the starting loads for Vhit N160 all have velocities in the 2700's and up. You are obviously not in a high pressure situation. Step on the throttle a little, loading in increments until the blackening/sooting stops.~Muir
 
Cartridge cases are the 'seal' for the chamber. If there is not enough pressure, the seal will not be complete. I don't know what your charge is but the starting loads for Vhit N160 all have velocities in the 2700's and up. You are obviously not in a high pressure situation. Step on the throttle a little, loading in increments until the blackening/sooting stops.~Muir

+1
 
I decided to have a 6.5-284 built and to find a load I started 3 grains less than max and went up in half grain increments at 3 grains under the whole case was covered in soot and and every half grain it got less until at one grain under max the case was clean at book max there were in prints of the ejector on the case base but no tight bolt but backed it off one grain and it shoots less than moa
 
Cartridge cases are the 'seal' for the chamber. If there is not enough pressure, the seal will not be complete. I don't know what your charge is but the starting loads for Vhit N160 all have velocities in the 2700's and up. You are obviously not in a high pressure situation. Step on the throttle a little, loading in increments until the blackening/sooting stops.~Muir

Muir

charge is 46g of N160 120g Nosler BT

According to Lyman, Hornady and Viht manuals I'm over but Lee manual says I'm short!

Cheers

Bryan
 
Cartridge cases are the 'seal' for the chamber. If there is not enough pressure, the seal will not be complete. I don't know what your charge is but the starting loads for Vhit N160 all have velocities in the 2700's and up. You are obviously not in a high pressure situation. Step on the throttle a little, loading in increments until the blackening/sooting stops.~Muir

+1. Also, if the brass has been fired & reloaded a few times, it may be too hard to fully seal, so annealing it may also help. The problem is certainly a failure to seal correctly in the chamber when fired.
 
Cheers guys, appreciate the info! Will try increasing the load and see how we go from there!
 
+1. Also, if the brass has been fired & reloaded a few times, it may be too hard to fully seal, so annealing it may also help. The problem is certainly a failure to seal correctly in the chamber when fired.
This

charge levels have to be very low to fail to obdurate without case hardening to add to the effect
 
Little take from Wikipedia below about Obturation, I had this on my old .243 started load too low and got blow back over the bolt and into my face, luckily I had safety glasses on as I always do the first time I try a new load. You can often see a ring around the neck of the spent case where it has obturated properly gripped and sealed the chamber.

Obturation in firearms ammunition,
With reference to firearms and air guns, obturation is the result of a bullet or pellet expanding or upsetting to fit the bore, or, in the case of a firearm, of a brass case expanding to seal against the chamber at the moment of firing. In the first case, this both seals the bullet in the bore, and causes the bullet to engage the barrel's rifling. In the second case, it seals the case in the chamber and prevents backward travel of gases against the bolt.
 
charge levels have to be very low to fail to obdurate without case hardening to add to the effect

Indeed they do.
If brass fails to seal (Obturate) correctly soot will pass down the insides of the chamber wall/outside brass cases.
If the charge is too low and the brass very new...incrementally increase the charge until the problem is resolved.
If the brass has been fired and reloaded a number of times...anneal the brass & bring it back to life.
Or...buy new brass.
Cheers.
 
49g N160 now giving me a clean case and a ragged hole grouping with 2700ft/s. A lot happier I am!

Cheers for the info guys!

Bryan
 
Glad it's sorted, but FWIW I had the same problem a while ago with my 308. The solution seemed to be to tumble the cases again after re-sizing to make sure the sizing lube had all gone. Sounded unlikey to me, but it did the trick...

Andrew
 
Could very well be part of the issue Andrew!

So much variables with reloading though, an entire different pass time altogether!

Cheers

Bryan
 
Have you had your chrono checked?
Nosler suggests a max of 46.5grn for 2852fps.

As nearly ever barrel is different the loading manuals can at be be a guide. Some may think that the internal dimensions of barrels are set in stone but they are not or else there would not be the variation that is found in them. The velocity loss may just be deeper grooves that the rifle or barrel used by the loading data publisher or it may be the bore is slightly larger and thus reducing the pressures.
 
He was shooting his 260rem and 223, his speeds were as expected, can't remember what they actually were but it was what he expected to see.
 
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