When I change lot #'s on any powder I back it down and build it back using good Chrono to known previous speed. Always has worked for me sometimes nothing changes but sometimes you may need less or more powder to reach your known average speed.
Sudden pressure signs
- Thread starter Grizz1148
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Rick Richard
Well-Known Member
If not different lot number on powder, big temp change, then look for carbon ring.
lancetkenyon
Well-Known Member
Is it a Savage .338LM by chance?
Grizz1148
Well-Known Member
No. Christensen
Grizz1148
Well-Known Member
Yes
WV338
Well-Known Member
I've had the similar problem when working with loads near maximum. In my case it was always fouling of the barrel. I found that Wipeout solves the problem. Good luck!
+1 to powder lot. First place I d look. If you have chronograph that ll help with verification based on velocity.
Chamber with oil/solvent also another place to look after powder.
Another thing not mentioned is possibly a longer case got into the mix.... that ll create pressure also. If you can find the case that showed pressure put your dial calipers on it.
Chamber with oil/solvent also another place to look after powder.
Another thing not mentioned is possibly a longer case got into the mix.... that ll create pressure also. If you can find the case that showed pressure put your dial calipers on it.
epoletna
Well-Known Member
Any chance your cases have stretched enough to change the neck tension? I didn't think much about modern cases stretching until one day I had problems with .243 cases that had stretched enough that neck tension was increased (presumably by "jamming" into the lede and the bullets had more starting resistance. Trimming to proper case length cured the problem.
I think you answered your own question - different powder lot. The 2/10 under is not sufficient to offset a lot variation., which CAN be 5% Was the old can of powder of recent vintage, or old? If old, and you worked up the load with it recently, that could also be the problem; some powders do not have good shelf life, and some do. Best to work up a load with the new batch. Also double-check the seating depth; a small increase in OAL can cause dramatic pressure excursions. Hatcher has some horror stories in that regard, and recently I read of a massive excursion that occurred with just a tiny increase in charge as in an increase from 65,000 psi to 110,000 psi(!) - similar to a slight change in formulation with the same charge. Have you contacted the mfr to ask about lot-lot variation complaints? See also re Retumbo:
https://www.ifish.net/board/showthread.php?p=9611858
https://www.ifish.net/board/showthread.php?p=9611858
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Grizz1148
Well-Known Member
Used wipeout just prior to firing. Always use wipeout and clean after every 15-20 rds
theosmithjr
Well-Known Member
What were the outside Temperatures on the days you fired the rounds? Was there a differance of 10 - 15 degrees? All loads should be developed in the warmest outside temps., you'll encounter on future shoots to be totally safe. Especially when you're at, or approaching MAX Load! Now if you're intending on using your loads in cold weather conditions ONLY, MAX loads will be safe, but be careful! Rule of Thumb. PLUS OR MINUS 1FT of Velocity per degree, from M. Velocity at time you tested load. You can equate pressure changes according to rise or fall of temp. accordingly using this rule. But take HEED, IT'S BEST TO DEVELOPE ALL LOADS in the WARMEST CLIMATE you intend to fire them in. That's the SAFEST WAY! Theosmithjr
sodakota
Well-Known Member
Seconds on temperature sensitive powder and temperature changing.
I have just pulled some 338 250 grain Nosler Partitions. Some were dated before mid-eighties, some were 90's and I have some new bullets. There are three versions which look very much different in jacket metallurgy and shape. This could be a sample of an issue, but I'm thinking lot to lot variation on powder OR temperature issues v
I have just pulled some 338 250 grain Nosler Partitions. Some were dated before mid-eighties, some were 90's and I have some new bullets. There are three versions which look very much different in jacket metallurgy and shape. This could be a sample of an issue, but I'm thinking lot to lot variation on powder OR temperature issues v
del2les
Well-Known Member
There is one possible. Oil or cleaner left in the chamber will cause a case to slam into the boltface and give signs of high pressure. Dry the chamber thoroughly before firing loads
