How much cool down time?

I am working with a 264 win mag testing loads. I know that heat can erode the throat. On a say 70 degree day how much cool down time between shots? For best accuracy on a cold barrel wile hunting how long between shots wile testing a load? If it is 1/4 in with a warm barrel and hits the same spot with a cold barrel, are we good?

Barrel cool down wait time is determined by how long you have to wait until the barrel is cool. Circular argument, but there are too many variables to state an exact time. Better to feel the barrel and approximate the same temp for every shot. Staying in the shade will help since the sun will beat down on the barrel and help heat it.

If in the sun you can hang a towel over the barrel to keep the sun off. If you moisten the towel it will aid cooling.

https://www.walmart.com/ip/Coleman-...tssaD-ffs09tOEtSZyfBmGzZssS1ThHRoCuqEQAvD_BwE attach a rubber hose to the nozzle and blow ambient air into the chamber end of the barrel for a minute after each shot.

I monitor my barrels with TempStrips from McMaster-Carr, to make each shot @ near same temperature. Also use the air pump from Walmart run with a motor cycle battery and damp towels in the heat of the Texas summer.

Is this a hunting gun? If it is, I'd fire 3 shots and then let it cool completely. If you fire one shot then let the barrel cool down between shots, you won't know how it groups in the event you need to make quick follow up shots while hunting. Even with chamberings like the 7 RUM, 6.5x338 RUM improved, 270 RUM, 338/408 Improved and plenty of other over bore rounds, I'll fire 3 shots then let it cool.

Saw this a while back but haven't ordered or needed it lately. Summer's coming though!
When doing load development, I usually start out 2-3 mins between each shot for "average" cartridges (i.e., .270Win, .308, .243, 6.5-284, etc.). As the barrel progressively gets warmer I extend the time and try to keep it comfortable to the underside of my forearm.
For magnums (70-100gns of powder) I might go 5 mins between shots. Depends on the day's ambient temp also.

Just feel with your hand. Too many variables (ambient temp, wind, powder, cartridge, sun). Usually 3 shots and a 10 minute cool down. That's why I bring 3 or more guns to the range.

Use a little stick on thermometer for a while and see for your self how long it
takes your rifle to cool between shots ..I have been surprised...
I have one now on my 338 LM I'll try to take a picture.

Thanks, I have been doing a 10 minute cool down. I will check the 3 shot without cool down once I get a good load. Have my bench in the top of my barn. Always shaded and doors open to help cool. I have a laser thermometer and will play with it on temperature cool down time.

Once you use one of these: https://www.amazon.com/dp/B008EW837S/?tag=lrhmag19-20 for one thing you'll find all sorts of other uses for it.

An important thing to know about them is the surface "Emissivity" can skew the results. Two ways to deal with this, 1) Always measure your temps at the same spot and from roughly the same angle; 2) paint a flat black spot on metals not already that color and always measure the temperature there. From previous experiments a machined aluminum surface is nowhere near as repeatable and consistent as a spot of flat black paint on that machined aluminum surface.

I used an inferred thermometer to monitor my barrel in the middle of summer once. In 90 degree weather, 4 minutes was time for a consistent barrel temp. Obviously not a cold bore test but consistent enough for load development. I tested with a quick 3 shot group and then shot a 3 shot group next to it with the cool down periods and they were the same within a margin of error. For 80 degs or less, I wait 3 min between shots to get the same barrel temps.
Right before the season opens, I collect some long range drop data and zeros using the fairly quick 3 shot group method.

guide4u said:

I am working with a 264 win mag testing loads. I know that heat can erode the throat. On a say 70 degree day how much cool down time between shots? For best accuracy on a cold barrel wile hunting how long between shots wile testing a load? If it is 1/4 in with a warm barrel and hits the same spot with a cold barrel, are we good?

Click to expand...

I've had pretty good results on monitoring barrel temp using a laser gun (not very expensive). Also, by placing the rifle in a vertical position with the bolt open, gives it a "stove-pipe" effect aiding with cooling. I live in Arizona and have had quite a bit of experience with "Heat". If you can, it's best to keep your rifle out of the sun between shots as the sun can play havoc with barrel heating. Just fuel for thought!

Get some ice and water in a cooler. Shoot 3 then cool with a towel dipped and ring from the towel. In about five minutes you'll be ready to shoot agai .