I'm sure this has been discussed here before but I can't find the info I'm looking for here.

When checking the precision of a rifle how long do you wait between shots? If you claim you have a 1 moa rifle does that mean you can shoot 5 times in a row without allowing the barrel to cool or does it mean your rifle can shoot 1 moa if you allow it to cool completely between shots?

Also when working up loads for a new rifle I basically have the same question. When you are shooting through a chronograph to check for speed differences in a load do you shoot 5 shots in a row then let the barrel cool before shooting the next 5? Do you shoot 1 shot and let the barrel cool before shooting the next shot?

The reason I am asking is because I just received my new APR .260 rem and loaded up some ammo for it last night.

Depends on the barrel contour, weather, etc...you don't want the barrel too hot. I've seen guys shoot their hunting guns one shot then let it cool because they wanted cold bore data and nothing else.

I know I didn't answer your question with a specific answer but hopefully it'll help a bit.

I shoot 3-5 rounds per group all together in about 1 minute. Then let the barrel cool down and shoot the next group of test loads. If it's summer time, the cool down time could be 15-20 minutes between groups. In the winter time, that can be 5 minutes. How many rounds I shoot and how I shoot those rounds is based on what the rifle will be used for. I will shoot a hunting rifle with a thin barrel differently than a competition rifle or target rifle used to shoot multiple rounds with a warm or hot barrel. I normally shoot 2-3 rifles at a time, and shoot a rifle while the other one cools. I'll rotate each rifle to the next. It takes me about 1.5-2 hours per rifle to shoot 3-5 test groups, and 3-5 rounds per groups.

If you have a thinner barrel, shooting more rounds and heating up the barrel will generally cause your groups to open up. This is why on a hunting rifle I shoot on a cool barrel and really pay attention to the first 2-3 shots. Often times when shooting groups on a thin barrel hunting rifle, shots will open up after about 3-5 rounds. So I may only shoot 3-4 rounds, and if shot #4 or #5 is constantly throwing the shot, then I'll shoot 3 rounds per group. For example, I had a thin barrel hunting rifle 300 RUM not long ago where the first 2 shots were fairly spot on but shot 3 and 4 would open up the group. In a hunting rifle, shots 3 and 4 are not as important as shots 1 and 2. And a thin barrel 300 RUM is not going to be a target rifle.

The main thing is to learn your rifle and the personality of your rifle with your tuned load to the rifle. Each rifle has one. But most shooters play with too many different types of ammo and bullets to learn the personality of their rifle, or they clean it every 10-20 rounds right when they are getting into the most accurate part of the time frame of the barrel. After cleaning, I know my 6.5x47 would shoot the most accurate groups from about shots 15 to shots 50. From shots 1-15, I'm still fouling it in, and seasoning up the barrel. After about shots 75+, it would still shoot good, but not as good as it did from about rounds 15-50. The main thing is to shoot enough to know your rifle's personality.

If you don’t have a heavy barrel I would highly recommend waiting in between shots. My T3 will hold 1/2 moa all day if I wait between shots. If I string 5 shots together it goes to 1+ evertime. For the purpose of load development you have to let the thin barres cool. Otherwise you’re wasting powder and time. I of course learned this the hard way. I knew better but was spoiled to heavier barrel rifles and wanted to make it shoot the same.

My rifle is an Alamo Precision Rifle with a Muller Works Stainless APR contour (#4-#5ish) fluted barrel. Its not a super heavy barrel, but I wouldn't call it a thin barrel either.

I like a #4 to #5 contour barrel as a "utility" barrel contour. It's heavy enough to maintain consistency for 4-5 shots no problem, yet somewhat light enough to still be functional without being too heavy to carry around.

When I build some of the Tikka rifles we do, I like the #3 and #3B Bartlein contour barrels for hunting rifles. They are thick enough to maintain consistency for more shots, yet light enough for a good hunting weight rifle. For reference, most sporter rifles are a #2 contour barrel.

I do 4 5-shot groups

let cool

repeat

the more groups you have the better the sample for you to draw conclusion
on 'average' precision potential of your rifle/round combo

I shoot a group as quickly as I can make accurate shots. This may be a 3 or a 5 shot group, depending on the rifle.

Note: I don’t mean rapid fire or anything, just that I’m not spending any extra time letting the barrel cool during a group. Before I go to a new load, I let the rifle cool completely.

With the barrel contour on your APR, 3 shot groups at a steady pace won’t be an issue. Five shot groups should hold up fine as well, but you’ll have to shoot it to find out. Let the barrel cool completely between groups while doing load development.

as far as the chronograph. I shoot three shot groups but average 6 per string, better average a SD and ES.

Just dont over think it, three shots are good. cool, shoot another rifle or wait for a cease fire. My range has them every 20 minutes. If its cool weather, i'll shoot 6 between cease fire.

I think you will know if you have a "precision" rifle.

About 1 beer between each shot

One thing that I've found can make a big difference is to not let a round sit in a hot chamber and let the powder temp go way higher before you shoot. If I'm shooting a 5-shot group, it probably takes me 1-2 minutes. But I start round in the mag, bolt open, get on target, close bolt and then shoot. I want to make sure I get a good shot off, but I don't waste any time once the bolt is closed. If I've spent 10 seconds behind the glass with the bolt closed and haven't pulled the trigger yet, I back off, pull the round out, and set it aside to cool off so it can be shot at the end of the group. Powder temp can be a big driver in group size, maybe not as much at 100 yards but definitely as you stretch out further. This can also be an issue if you're trying to read wind at distance and spend forever trying to calculate things while the round is cooking inside your action.

Of course, this is irrelevant for the first shot in a group and probably the 2nd really unless you really let it sit in there a really long time. But by the time I'm on my 5th, 6th, 7th shot, the action is blazing hot and it doesn't take long for the round to get much warmer than the first few rounds I shot, and why wouldn't you expect to see some variation in the output if there is significant variation in the input?