Re: Question about rifle barrels.
When I test ammo for accuracy during load development I will shoot up to five 5 shot groups all in a row with no cool down periods. Most all my guns are Varmint heavy barreled guns. With heavy barreled guns I see no degradation in accuracy. For fun shooting, once I have a load down, I will shoot 5 to 10 five shot groups without cool down periods if the range remains open during the series. Again no degradation in accuracy that I can see.
Now if I were shooting a bench rest gun in a bench rest match (I don't!) I most certainly would let the barrel cool as much as the match format allowed. But for fun shooting cooling the barrel between groups is over rated. At least that is my opinion based on my experience and my accuracy requirements. Yours may vary.
Unless you get the barrel red hot or at least smoking then no harm is done to most barrels with relatively continuous shooting. Most range situations force cool downs as the range is closed to allow target changes on a pretty regular basis.