Sudden pressure signs

[MarkA]

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.

 

[Rick Richard]

If not different lot number on powder, big temp change, then look for carbon ring.

 

[lancetkenyon]

Is it a Savage .338LM by chance?

 

[Dosh]

1148, were the cases sized prior to loading?

 

[Grizz1148]

Is it a Savage .338LM by chance?

No. Christensen

 

[Grizz1148]

Yes

1148, were the cases sized prior to loading?

 

[WV338]

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!

 

[fmuguira]

+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.

 

[epoletna]

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.

 

[GeorgeS]

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

 

[Grizz1148]

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!

Used wipeout just prior to firing. Always use wipeout and clean after every 15-20 rds

 

[theosmithjr]

why would a load suddenly have bolt lift issues? Same load that I have shot the last several days, built on the same equipment, same dies, same brass, same bullets, primers, powder same type (retumbo) but new bottle. Double checked scale to be sure it was calibrated, pulled a bullet and weighed charge to be sure and it actually came out 2/10 under for some reason but less anyway. Any ideas?

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]

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

 

[del2les]

Just cleaned night before firing, shot it yesterday and the day before with no issues

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