Fireforming in cold weather resulted in split necks

[M.Stilley]

Fireformed some 6 Fat Rat brass yesterday. I had only ever previously done so in the summer, and had no lost cases. Yesterday I shot 10 fireform loads, and stopped after I lost 3 of them to split necks. The only difference from the summer was that temps yesterday were in the 30s as opposed to the 90s.

Anybody else experience that before?

 

[alinwa]

5yrs ago I would have discounted this..... but, I work in construction with rebar, we've had a couple wikkid cold winters here in WA and my guys were complaining "the rebar's breaking when we bend it"

And I DID scoff it off...... "cold" here in WA is 25-30 degrees........ I'm like "steel melts at what, 2500 degrees??"......

But I was WRONG! Rebar definitely becomes brittle in cold weather.

I have no idea whether this is relevant but now I'm interested to try a test. I will be freezing some fireform rounds

 

[mikecr]

Same lot of brass? Same prep annealing? Same chamber?

 

[jepp2]

I have never experienced it. And I would be more suspect of the this brass cracking due to work hardening than I would low temperature. The hot gas that causes the shoulder to fireform is going to generate heat to warm the brass so the ambient temperature is not of consequence.

 

[Rsadams]

I watched a program were they were saying in Alaska it gets so cold even steel breaks , losing half it's strength or even more... Yet that's Alaska.. it definitely gets cold there....

 

[M.Stilley]

It is not work gardening or cyclic fatigue when you’re forming new new never fired brass.

Also, it was identical to summer fireforming loads. Same blue box of brass. The temperature is precisely the only difference. I wouldn’t have done if I knew that was gonna happen.

My hypothesis is that it’s due to the more rapid cooling.

 

[rickiesrevenge]

Could it be that you'd have lost those cases anyway? I normally lose 1 or 2 when making dasher brass. Not saying that its for sure.

Aaron

 

[jds holler]

Riflewoman where arrrrre youuuu?? jd

 

[JayHHI6818]

How long was the brass loaded for? I recently fired 5 fireform loads and fired split necks. Virgin 444 Marlin Brass necked down to 338 aka 338 JDJ cartridge. I kinda forgot about not shooting all of the fireform loads. 8-10 months have gone by since I loaded them. I have seen this before after they sit for a while. Will pull them down anneal and loaded them up again.

 

[SWRichmond]

There IS such a thing as brittle fracture, though I am unable to find information for cartridge brass. One of the engineering properties of steel alloys is their "reference transition temperature"; in essence, this is the temperature at which they are considered to stop behaving in a ductile manner and fail in a brittle manner. In other words, when you stress the metal to its failure point, will it first deform under stress (stretch) or will it break all at once?

https://www.designnews.com/material...ctady-lesson-brittle-fracture/173702193545746

Interestingly, the materials literature on cartridge brass lists "cold workability" as one of its desirable qualities.
http://www.matweb.com/search/DataSheet.aspx?MatGUID=aeac472e2ef04f12bddb09ea8fab8379

 

[M.Stilley]

How long was the brass loaded for? I recently fired 5 fireform loads and fired split necks. Virgin 444 Marlin Brass necked down to 338 aka 338 JDJ cartridge. I kinda forgot about not shooting all of the fireform loads. 8-10 months have gone by since I loaded them. I have seen this before after they sit for a while. Will pull them down anneal and loaded them up again.

Hmmm this might be it too.
Brass was sized from 6.5 Grendel to a 6mm false shoulder back in July. I fireformed the first batch that same week with no losses, and came back to the job yesterday.

 

[M.Stilley]

Could it be that you'd have lost those cases anyway? I normally lose 1 or 2 when making dasher brass. Not saying that its for sure.

Aaron

Plausible. 85 cases done in July with no losses, and 3/10 fail yesterday. Far odds, but possible.

 

[thatguyshm]

I just fire formed 22-250 AI brass in 25 degree weather with a wind chill, no lost brass.

I would try firing a few formed pieces to warm the chamber and keep those few left to form in your jacket to keep the temp up on the brass to be formed if a warm vehicle isn't available.

 

[dcali]

Strangely, cold temperatures make brass stiffer, stronger and more ductile than warmer temperatures. Perhaps there is some other way that cold temperatures come in to play, but it’s not material properties.

 

[dedogs]

Anybody else experience that before?

Up your fire-forming load for colder weather. 60* temp.difference is significant. dedogs

 

[NorCalMikie]

Me thinks you should have "annealed" more often. Hard brass splits more easily.

 

[stifffingers]

Me thinks you should have "annealed" more often. Hard brass splits more easily.

This may work. Fire a couple of formed cases to worm the barrel, then take one round at a time out of an inside shirt pocket.