Wayspr, a three shot group is the norm when working up loads for a hunting rifle as it is typically all the shots you are going to get at an animal, before it's either dead or runs off unscathed.

If you want to shoot groups with more rounds for accuracy testing, you should let the gun cool between rounds fired. As a barrel heats up it will "walk" and your groups won't be real world first shot accuracy representative.

As far as working up loads, what I do is find the bullet I want to use and then try as many powders as I can behind that bullet.

I make 4 bullets for each powder type. I make 1 bullet at the hottest load listed, one grain below that, and2 below that (one for a fouling shot). So if the max load is 57 grains, I'll make one at 57,56, and 2 at 55.

Starting with a clean gun, fire one of the lowest grain loads of the first powder. This is a fouling round. Typically a clean gun will throw its first bullet to a different point of impact than the following rounds. Mark that bullet on the paper (at least in your mind) and then fire your other lowest grain round. while watching for signs of pressure, fire the next hottest and then the max load. Mark that target with a pen as to what it was, primer, powder charge, and bullet, brass etc. Typically I will measure them and document that also.

Then put up a fresh target, and clean the gun. Repeat this process with each powder type, always watching for signs of pressure. If you see telltale signs of pressure, stop there.

What you will see is one powder, even though made with varying charges, will group very well. Take that powder, charge,bullet,primer combo and make a dozen or so rounds. And go back to the range with a clean gun and fire several groups, letting the barrel cool between volleys.

What you are looking for is the "hottest" load with the best accuracy. It must also be a load that you can shoot comfortably that doesn't cause you to flinch.

This process will save you a lo of money in components and time. I used to go through 100 or more bullets searching for recipes for different guns, and this cuts down the expense considerably. Check with friends for different powder types instead of buying them just to try. They can then borrow some of yours when searching for that perfect load.