Barrel temperature

[MakeItHappenCaptain]

Metallurgically, at what temperature should you be giving your barrel a rest?
Is there a specific temperature (excluding second degree burns when you feel the barrel ) where a barrel will start to develop excessive wear (burn out)?

Not after "x rounds in my .xxx varmit" or "if you can't keep you hand on it for five seconds", more a scientific temperature range.
Cheers.

[Baz460]

I find that 3 shots in a row out of my 257 Weatherby, then it's time to give it a rest.

[AusTac]

depends what your going for really, heeeeeaps of variables but on my .303 for target work about 1 shot a minute keeps it cool enough usually and when im just messing around shoot shoot and shoot who cares just don't but it near anything you don't want melted or hot

[happyhunter]

How long is a piece of string? Some get hot fast, some don't.. some have crome bores.. some have water cooling.. etc.

[Chronos]

when the POI drifts outside the acceptable range or when you believe there's enough heat to damage the bore. firecracking is a great way to ruin a barrel, it's why a lot of military barrels use chrome lined bores

Chronos

[No1Mk3]

G'day MakeItHappenCaptain,
There is no practicable temperature, metallurgically speaking, that you can possibly achieve with a repeating rifle where you would suffer true burn out. Machine guns can reach the Point of Decalescence and continue to operate for a while, though life is dramatically shortened, think MG42, etc. The best you might make is tempering straw, which equates to appx 220C. As the others posted above, to get best life, rest when shots start to fall off, Cheers.

[David Brown]

Most of us have trouble loading that fast :-0

Hey MIHC……I eventually (9 months now) and two instruments (4 actually) and $640 latter have successfully educated CASA how to issue a carriage of firearms instrument.

Drop me a line if you want to know more

[Homer]

G'Day Fella's,

Apart from some Ham Fisted Phuckwit that has no idea how to use cleaning gear properly, a barrels worst enemy is HEAT!
When I'm out hunting or competitive shooting, the barrel will get hot at times from use, that what it's there for.
But any time I'm at the range working up loads, sighting in etc, I wait a couple of minutes between shots, just to allow the barrel to stay cool!!!

Hope that helps

Doh!
Homer

[Ben78]

4140 steel is tempered in the range of 150°c to 200°c. You would need to exceed this to cause a permanent change to the steel structure. Keep in mind that the throat may exceed this easily without the barrel external temp being more than warm. Warming the barrel up to 55° on a 25° day would show measurable increase in the bore size (through expansion) and may change poi.

[RealNick]

What about stainless?

[Ben78]

What about stainless?

431 Stainless is Tempered in the 590 degree+ range so shooting temperatures have even less impact on metallurgy when compared with 4140 barrels.

[Gwion]

Long strings of fire with even a moderate charge/cartridge, say 223rem, can and will alter surface metallurgy within the bore of the barrel; particularly at the throat end. This is one reason why you get throat erosion.
https://www.youtube.com/watch?v=fOmco59yJs8 <<<chemical bore erosion
https://www.youtube.com/watch?v=jeAdf4bN6kg <<<thermal bore erosion

[happyhunter]

What about stainless?

431 Stainless is Tempered in the 590 degree+ range so shooting temperatures have even less impact on metallurgy when compared with 4140 barrels.

Thought most rifle barrels were made from 416R.

[Ben78]

Thought most rifle barrels were made from 416R.

Probably - I'm no gunsmith.

416 shares a similar tempering range to 431 however.

[Wobble]

What about stainless?

431 Stainless is Tempered in the 590 degree+ range so shooting temperatures have even less impact on metallurgy when compared with 4140 barrels.

And to throw another one in the mix there are 4150 barrels which can take a temp somewhere in the middle I think. (Can't remember the number off hand)

[happyhunter]

4140 is the most common. 4150 has a higher carbon content so it's a harder wearing alloy and not as common due to expense. I wonder if anybody has tested the effects of heat on barrel steel (at the throat) using metallographic techniques? This would reveal changes at the microscopic level and answer the question of what changes really occur.

I'm guessing that due to the extreme short period the metal is hot that there would be minimal changes to the steels physical properties (hardness ductility, etc..), and most of the damage would be from melting and wear. but again, that is a guess.

[Farmjer]

4140 is the most common. 4150 has a higher carbon content so it's a harder wearing alloy and not as common due to expense. I wonder if anybody has tested the effects of heat on barrel steel (at the throat) using metallographic techniques? This would reveal changes at the microscopic level and answer the question of what changes really occur.

Know any rifles/barrels made with 4150?

Just curious where it is used.