Time between strings on randsom rest

First topic message reminder :

I already load an extra sacrifice round that sits in the chamber and is fired over the target before testing each group.  That way I do not have to touch the gun i.e. rack the slide but only change magazines.

My question is assuming you are testing multiple groups of 5 or 10 rounds, do you allow the barrel to cool between shooting groups and how long do you wait?

The reason I ask is I am trying to figure out if a hot barrel will affect groups size and shape.

Clamping the barrel in a fixture for accuracy testing is the way a lot of European manufacturers test their barrels. Many times the little test targets were fired that way. Does it represent the real world? Of course not, but the results indicate the inherent accuracy of the machine work of boring, rifling, chambering, and crowning. Any accuracy issues lie elsewhere.

Assembling the barrel into something then clamping that something into a fixture brings the whole system into the accuracy puzzle. Do barrel harmonics change? Sure. Do they matter? Probably not as much as the other accuracy drains, at least in pistols. Pistols are NOT precision rifles. They’re not as precise as an AR. As Jon said, a good pistol shoots into 1.5 inches at 50. That’s a 3 MOA gun. The average combat pistol is a 6 to 8 MOA gun.

I suggest the OP fire a Ransom test of 25 shots in 30 minutes followed by repeated 10 shots as fast as possible.  Have a partner spot to see the first shot from mags.  Take notes