How hot to shoot?

[dleeds]

Doing some HVAC work, I picked up both an Infrared thermometer and a Multi-Meter thermocouple. I can use either to get an exact temperature reading on my barrel instantly. So, here's the question- How hot should I shoot my barrels? I would take readings at the throat area, where Temp should be highest.

The question comes up in multiple facets.

1. During load development, what Temperature will affect accuracy? As in, can I shoot 1 group before cooling, 2 groups, etc?
2. What does the Temperature versus barrel wear relationship look like?

 

[spife7980]

What begins to effect the accuracy depends on your individual action and barrel fitment. If I can hold my hand on the barrel just in front of the scope without the sensation of it being too hot then it's fine. Once I place my palm to it and no longer feel I could comfortably leave it there I let it cool. About one shot ever four minutes on average here in Texas, lately it's been one every seven minutes and that's with a chamber chiller. Some say that the heat has no effect, I say they have a great set up, are lucky, or just careless. I daisey chain or snake my groupsnin load development to spread the heat and conditions out between them all. To answer number two heat eats barrels.

 

[Milo 2.5]

Doing some HVAC work, I picked up both an Infrared thermometer and a Multi-Meter thermocouple. I can use either to get an exact temperature reading on my barrel instantly. So, here's the question- How hot should I shoot my barrels? I would take readings at the throat area, where Temp should be highest.

The question comes up in multiple facets.

1. During load development, what Temperature will affect accuracy? As in, can I shoot 1 group before cooling, 2 groups, etc?
2. What does the Temperature versus barrel wear relationship look like?

First one, all rifles will quit being accurate when a certain temp is reached, with each being different. I'd develop the load in conjunction with the manner it will be shot. If when you go to the range, do you shoot 1 shot every 3 minutes for a length of time, then cool, or do you progressively run down the range shooting up to 12-15 shots then let things cool down? If you shoot your rifle in a constant state of warmth, develop the load in those same conditions, if a hunting rifle, shoot 3 and let it cool way down, for me, I quit at 10-12 depending on ambient temp.

2nd, the inside of the barrel is way hotter than what you feel on the outside, have you ever recovered brass immediately from a bolt gun? The more you shoot the hotter the brass feels yet the outside of the barrel does not feel that warm, there's a reason. If your gun gets hot and you keep hammering rds down it, the erosion occurs at much faster rate, nothing linear here. Crude example, have you ever ground a broken weld off a plate, the hotter the bead gets the easier it is to peel off.
You may also hear horror stories from older guys, in a prairie dog town and one just a little too far out stayed up grinning at them, and they kept shooting, then it was over for good, rifle was toast and they never knew about rebarreling. Don't laugh, it's probably true, but make no mistake, barrel steel today 3-4 times better today.
145 deg on the infared seems a good number, most of us non welders cannot hold our hands under 135 deg tap water, but barrel steal was probably heat treated at 1200+

 

[black5.3]

I follow the same method. If i cant hold my hand on the barrel any where and leave it there for a duration of time then it needs to cool. This all depends if im shooting direct sunlight/shade, load development, or banging steel.