Looking for advice please on neck tension. I am having issues with sooty necks on my 7x57 and struggling to get consistency. I understand that the sooty necks are due to unburnt powder/escaping gasses in teh chamber. I am unsure if this is because the brass necks are getting hardened and so not expanding enough or if I need to crimp/sort out neck tension? I have less of a problem with higher pressure loads, so thinking I need to work on neck tension? Any advice appreciated.
Should I crimp or use different brass?
- Thread starter BWH
- Start date
Uncle Norm
Well-Known Member
I would wager a few £££s, that if you load to factory oal and crimp with the Lee Factory Crimp die, the sooting will be gone and consistency noticably improved 
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Have you chrono'd your loads? I suspect that they are anemic.
Regards
JCS
Regards
JCS
Thats very kind of you. I am currently using Winchester brass but was contemplating switching to Nosler or Norma. I understood the winchester had the greatest capacity which is why i chose it, but might try the other brands before I go down the annealing route.
Cases with sooty necks is typically a sign of poor obturation, usually associated with weak loads as another member has indicated. However if you are pushing 140gn at 2850 you're well above what you should be doing with the 7x57, 2700 is pretty much max for this cartridge and that bullet weight.
How old are the cases? As has been mentioned annealing would be a good option. I have used a variety of different brands in mine but if you can get it I recommend RWS brass, Norma is pretty good too, I haven't tried Nosler yet but it looks expensive for a new kid on the block. I'd avoid Sellier & Bellot, it's a bit on the thin side and doesn't seem to last long.
How old are the cases? As has been mentioned annealing would be a good option. I have used a variety of different brands in mine but if you can get it I recommend RWS brass, Norma is pretty good too, I haven't tried Nosler yet but it looks expensive for a new kid on the block. I'd avoid Sellier & Bellot, it's a bit on the thin side and doesn't seem to last long.
If annealing and sorting neck tension then crimping doesn't sort out the sooting, try increasing the powder charge (in small steps, watching for pressure signs) and as an alternative try some hotter primers, maybe even use magnum ones. Obviously it is best practice to back off at each option and work up to avoid any nasty pressure spikes. Change one variable at a time and test it.
As JCS indicated a chrono would help guide you.
The inconsistency will be because you aren't reliably sealing the chamber by obturating the case quickly enough on ignition.
Decent brass helps, but if you anneal you can get away with poorer stuff.
Ian
As JCS indicated a chrono would help guide you.
The inconsistency will be because you aren't reliably sealing the chamber by obturating the case quickly enough on ignition.
Decent brass helps, but if you anneal you can get away with poorer stuff.
Ian
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Foxyboy43
Well-Known Member
As with SpikeD your loads appear to be very hot. For 140gns the Lee book shows top end "Never Exceed" as 2836 fps for one load only and doesn't even list R17 for that round nor incidentally does my elderly Hercules Guide (nearest is R19 x 51.8 = 2835 fps for 139gns Sp. Pt.) or indeed the manufacturer's own (internet) manual. That aside symptoms, subject to above caution, do suggest poor obturation so neck sizing would be the first suspect.
The rifle is a modern rifle so I am loading it to pressure levels comparable to similar rounds. I have done quite a bit of research on the cartridge and loads and am happy that I am not getting excessive pressure with this powder. I have a chrono and am working up loads using it. I was going to try Nosler as I think it is made by Norma? It was in certain chamberings, not sure if 7x57 is one of them.
A quick anneal of a couple of the old brass would indicate whether work hardening was the problem, worth doing even alongside working up loads with new brass.
Ian
Ian
Yes on the out side and therefore poor obturation hence my question on how to resolve? Is poor obturation a brass issue ( too hard-needs annealing) or a pressure issue ( better crimping or neck tension)? Maybe I dont understand the term properly?
Utectok
Well-Known Member
Put a small drill in the Chuck that fits in the primer hole play flame on neck and shoulder while rotating then drop in a pan after 6-8 seconds very dull red noticeable in the dark. I built my own annealing machine but despite what they say it’s not that difficult to do it diy.
I seen loads about like that published in HandLoader Magazine. I would anneal first, however I def would not add powder the other brass may behave the same but work up before going full throttle. Even so you may get sooty necks, no worries if they soot just tumble clean.
deeangeo
Well-Known Member
Anneal the brass. - As other's have said.
The case neck/shoulder isn't sealing (Obturation) because the brass has hardened. Annealing should restore the pliability of the brass to seal correctly.
Annealing is an easy process & doesn't take long. I just use a blow torch & hand hold the cases. No need to quench, just put the cases onto a damp cloth to cool when done.
The case neck/shoulder isn't sealing (Obturation) because the brass has hardened. Annealing should restore the pliability of the brass to seal correctly.
Annealing is an easy process & doesn't take long. I just use a blow torch & hand hold the cases. No need to quench, just put the cases onto a damp cloth to cool when done.
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