Barrel too hot???

[MAH]

cooling the barrel between shots or short strings when zeroing.

Its a good question. And a topic I'd like to understand better.

My rifles are sporting rifles, pencil like barrels, some are old classics.

There are two issues for me:

a) A temporary wander or widening of a group as a barrel gets hot. Which is not too much of a concern for me.

b) Permanent damage to the throat caused by the increased erosion of successive shots in a barrel that is too hot.

And "b" is the crux off it for me.
Whats is a long fast string for a sporting rifle?
5 shot in 90 seconds?
Does the rate of throat erosion disproportionately increase if the barrel is too hot
What is too hot?

I know these question might prompt very subjective answers, but I'd appreciate people's thoughts. Especially from those with experience of metallurgy, or barrel manufacturing.

M.

 

[Smellydog]

There is a link between heat and accelerated errosion but I know no values.

All I can imagine is just how intense the heat must be on the throat surface in order to warm pretty much the whole barrel. So adding rapid fire or near, relatively, continued intensity is not going to help longevity.

 

[MAH]

continued intensity is not going to help longevity.

Yep. That's my layman's view too..
Fingers crossed there are some metallurgy experts on here who can give some tangible guidance.
M

 

[Heym SR20]

I have heard this before but never ever witnessed it myself.
I have only limited experience with double rifles and combination guns but never saw them walk as you describe.
I fail to understand the concept.
The heat that wants to warp one barrel that is joined to another barrel would also have to bend the other barrel.
The structure is a rigid structure.
Also heat is readily absorbed along the joints. A double rifle has potential for good cooling or even heat distribution within a limited number of shots.

Do you have any links to testing this please?

No don’t have any links but it’s common knowledge. I suspect whats going on is the barrel heats, but one side is thin and the other is soldered to a thicker barrel and thus heat is adsorbed quicky. Thin side gets hotter and thus expands more.

I also suggest with bolt actions how well the barrel is fitted to the action and then how square bolt lugs are etc will also make a difference in how the rifle shoots.

Many older rifles would shoot well when cold, but would wander as things heated up. Things like Enfields and Mausers which were turned out in huge quantities with minimal hand fitting were generally accurate enough for battle field, but particularly accurate ones were selected for sniper use.

Main work of custom builders has always to true up barrel threads and bolt lugs to give consistent performance.

 

[Smellydog]

No don’t have any links but it’s common knowledge. I suspect whats going on is the barrel heats, but one side is thin and the other is soldered to a thicker barrel and thus heat is adsorbed quicky. Thin side gets hotter and thus expands more.

I also suggest with bolt actions how well the barrel is fitted to the action and then how square bolt lugs are etc will also make a difference in how the rifle shoots.

Many older rifles would shoot well when cold, but would wander as things heated up. Things like Enfields and Mausers which were turned out in huge quantities with minimal hand fitting were generally accurate enough for battle field, but particularly accurate ones were selected for sniper use.

Main work of custom builders has always to true up barrel threads and bolt lugs to give consistent performance.

Yes absolutely re barrel shanks and lock up. I use to check bolts by blacking the lugs to see if they both made contact.

Yes I understand the concept of the expansion on the unsoldered side but for it to bend it would also have to bend the other barrel which I doubt. It is also fact that the soldered side is also a heat sink rapidly lowering the temperature of the hot side.

I also have never heard of it happening in shotguns.
Automatic and pump action shotguns yes, but not doubles. They are just to rigid. The moment of movement for two tubes welded together across their width is tremendous.

I have straightened curved pipes by simply adding hot spots along its length but two welded together are all but impossible to move with heat.
I would love to see it for myself so I could marvel.