How hot is too hot?

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Re: How hot is too hot?

Post by sungazer » 11 Sep 2018, 8:48 pm

You really think that a heavy barrel will dissipate heat more slowly. I would have thought that the extra metal being very thermally conductive to the bore would heat sink the heat away more quickly. Then the heavy barrel would also have more surface area so that heat would dissipate more quickly to the surrounding air.

For most target applications it is not really an issue as you may fire your 12 shots in 3 min which would toast a sporter but it is then an hour till the next volley.
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Re: How hot is too hot?

Post by Chronos » 11 Sep 2018, 8:55 pm

Gwion wrote:Barrel weight has nothing to do with how quickly a barrels throat & bore heats up and this
is what will effect barrel degradation. Rate of fire and amount of powder burning is what determines the rate at which the barrel will heat up. Barrel weight will effect two thing, though:
1/ a sporter weight barrel will be more effected by a wandering point of impact due to barrel heat but will cool down faster due to a higher surface area:mass ratio. As such, you can fire fewer rounds in quick succession before point of impact is effected but the barrel will cool more readily and so avoid over heating the throat and bore.
2/ a varmint or target weight barrel will be less effected by wandering point of impact due to thermal changes in the metallurgy due to the structural stiffness of a heavier cylinder but the internal heat will dissipate more slowly due to higher mass and less surface area and so it will be potentially easier to damage because you won't realise just how hot it is getting internally and be tempted to keep punching rounds through it.

Other things to consider are that the detrimental effects of heat on your barrel are only as problematic as your intended use and that three round groups are statistically close to useless when testing ammo for target work.


Not sure I agree G, a barrel with more material will soak heat away from the internal surface better and tend to have dramatic temp spikes

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Re: How hot is too hot?

Post by Gwion » 11 Sep 2018, 9:08 pm

It may take marginally more rounds to reach the same temp but higher mass will definitely hold heat longer and the cooling effect of the the surface area will be less effective at cooling it. There is not a heap of difference in mass at the chamber end of barrels unless you're talking truck axle bench rest rigs and this is the area we are talking about being most effected by heat. The fact that a thinner barrel has more surface area to mass helps as a heat sink to draw heat from this area more quickly.
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Re: How hot is too hot?

Post by Gwion » 11 Sep 2018, 9:15 pm

This would be a good thing to test if you had barrels to burn. Take a thick barrel and a thin barrel and see which one burns the throat out the fastest when shot under the same regiment. I'm tipping there won't be much difference.
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Re: How hot is too hot?

Post by YoungSC » 13 Nov 2018, 2:58 pm

I have a small infrared thermometer bought to measure the electric motor temperature on an RC car. Something along the lines (but not the same) as this: https://www.ebay.com.au/itm/Non-Contact-Mini-Infrared-Thermometer-IR-Temperature-Measuring-Digital-LCD-S8Q2/292620488982?epid=8017719467&hash=item44218a5116:g:aNYAAOSw64xbNA58:rk:24:pf:0

I was recently shooting 3 round load development groups with a 6.5 Creedmoor varmint barrel and taking a temperature reading once in a while.

Before firing, the barrel was around 26 degrees, around the outside temperature. After 3 warm up shots it read ~29 degrees, which was surprising as I thought it felt warmer than that.

Subsequent loads would get up to 40 degrees, which felt quite warm to the touch, again felt warmer than the reading. I'd let the barrel cool to read 35-36 degrees and worked through the remaining groups within that window.

Google suggests that 42 degrees is the lower end for the onset of the threshold of pain, so maybe the reading was accurate.
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Re: How hot is too hot?

Post by Daddybang » 13 Nov 2018, 3:09 pm

I had a conversation with my dad a couple of months back about hot barrels. ..he laughed and said "ya shouldve put ya finger on the barrel of my slr after a run in!!!..still shot straight the next time I needed it!!" :thumbsup: :drinks:
This hard living ain't as easy as it used to be!!!
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Re: How hot is too hot?

Post by bigrich » 13 Nov 2018, 3:57 pm

Daddybang wrote:I had a conversation with my dad a couple of months back about hot barrels. ..he laughed and said "ya shouldve put ya finger on the barrel of my slr after a run in!!!..still shot straight the next time I needed it!!" :thumbsup: :drinks:


an SLR DB ? those were the days. ;) saw another beauty on ozgunsales i think , browning BAR 30-06 . wonder if the 20 round mags from the US army version woulda fitted ? bulk firepower :D :drinks: :thumbsup:
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Re: How hot is too hot?

Post by Daddybang » 13 Nov 2018, 4:11 pm

bigrich wrote:
Daddybang wrote:I had a conversation with my dad a couple of months back about hot barrels. ..he laughed and said "ya shouldve put ya finger on the barrel of my slr after a run in!!!..still shot straight the next time I needed it!!" :thumbsup: :drinks:


an SLR DB ? those were the days. ;) saw another beauty on ozgunsales i think , browning BAR 30-06 . wonder if the 20 round mags from the US army version woulda fitted ? bulk firepower :D :drinks: :thumbsup:



Would loooooovvvvvveeeeee a Bar or an slr...
But f@#k getting shot at to get one!!!
:lol: :drinks:
This hard living ain't as easy as it used to be!!!
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