Tried a couple of DIY ways to cool a rifle barrel down when needed and wasn't happy. I also thought it might be worthwhile having approximately the same barrel temperature at the start of each group especially during load development. Finally ended up with:

86°-140° LCD Thermometer Strip

USB Rechargeable Inflatable Bed Pump (Click the underlined "Amazon" for link)

The thermometer is affixed on the opposite side of the barrel, not visible in the photo below. The air pump included a few fittings, one of which was used to route the output through a length of plastic tube from the local hardware store. Yes, we still have one lol.

With the outside temperature at 62°, the pump cooled my 338LM's barrel down to the same indicated starting temperature 8 times taking about 2 minutes each time without running out of power. A battery pack like the one powering the Labradar can provide power directly as/if needed. We'll see what it takes when the temps around here warm up a bit more. IOW, on these days at these temps with a rifle that gets hot very quickly the pump worked great.

Maybe others have found better/cheaper ways?

Since I always take several guns to the range, I just lay aside the fired one while shooting the others. By the time I get back, the barrel is warm to the touch but not hot. I guess if you are a precision accuracy shooter, that system would fine.

Obviously you are someone who takes Accurate Shooting to the next level.

One question concerning your LabRadar. How well does it work when you have shooters firing in the next lane? I've always wondered how discriminating these units are and they are so new to the market that it's difficult to find reviews that one can be sure aren't being put forth by the manufacturer.

I'll also point out that localized cooling of your barrel could cause a temporary "distortion" of the barrel so would advise that you allow your cooling unit to work slowly. Quite simply if you look for something "faster" I suspect you'll find your results cause more issues than solutions. BTW, one idea for an alternate would be a car battery "jumper pak" hooked up to a 12V to 120V invertor and a simple table fan. Thought behind this is larger volume of air distributed over a larger area. However, if what you are using is doing the job well I see no need to reinvent the wheel.

Water cooling is more efficient, but out of fashion these days.

I used a battery pack at work with an internal 120 V connection on 50 watt load. Usage was in general 4-6 hours a day, 4 days a week and 3-4 months a year. Total battery life was about 1 1/2 years with a daily recharge.

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Front sight and squeeze

This is my preferred method. My range has vertical storage racks. If you leave the rifle in the vertical position with the bolt open convection aids in the cooling. I seldom shoot more than one group before switching rifles except if I'm shooting a .223.

Works great for stainless and plastic guns. Too much trouble for me if the gun is blued steel and wood.

Not much wood on the Vickers, plus there is a generous supply of hot water for cleaning up after corrosive primers. Shoot one round of dubious military surplus ammo you may as well shoot a couple thousand.

Re Cooling: Agree . . . faster would probably mean cold air which could lead to condensation inside the barrel. The 12V battery + fan might be OK if I shot off the back of my pickup . . . but I'm not hauling that kind of extra weight lol. Earlier I did use a small USB fan, but it didn't move nearly enough air.

Re: Labradar: My experience - and what I've read in discussions here and on other forums - is that if you shoot unsuppressed at velocities under 4k fps, you're OK. I've fired a 308 from a 10-position shooting house (roof, 3 walls, concrete floor) with 8 active shooters (sounded like a war zone) and had no issues adjusting the LR to pick up just my shots. OTOH, I've had a braked 300WM shooting next to me as the only other shooter in that same house and it was harder to adjust the LR to ignore his shots while picking up mine. Bottom line, the more I've used the LR (I rarely shoot without it now) the more perfectly pre-adjusted it has become.

If the LR does react to an adjacent shot, it won't find that bullet so it will say "Error" and record nothing. You reach over and press a button and it's ready for your shot.

Missed that one. My father-in-law was saddled with a M1917 water cooled on Okinawa. It served him well and he had the decorations to prove it. He seldom talked about it, but did mention it was possible to boil them dry and cook a barrel.

He died last fall in his own bed at 95.

I use a Coleman battery-powered air bed inflator. 4 D Cells, and a piece of 1/2 in.(?) tubing, and it works just fine. I don't go to the range when it is really cold, so no condensation worries.