Serious load testing is not a process to be done with impatience...While I agree with a wet towel to speed up barrel cooling, I also take a fold up chair and a book, planning on a 'several hours' session...with much leisure thrown in...Fortunately, our shooting benches are covered, so direct sun is usually not a factor..
Your chamber will retain some residual heat and ammunition is best kept in a small cooler to resist temperature change from ambient heat..
