Okay, rifle is a ruger american hunter, scope if a 16x SS, the rifle shoots very well over all.

Shooting hornady american gunner ammo at 200 yards I get consistent 1/2 moa or close groups. Problem is I am running out of the ammo.

I have reloader 16, 147 eld bullets and br primers. My loads I have tried are 40.9, 41.5 and 41.3 grains, setting depth is 2.825 oal, the higher loads shoot better. Both of the higher loads will put 3 rounds with in a 1/2 inch at 200, but put the other 2 out of 5 an inch to 1.5 away from the other 3. I am weighing every load, to the point of watching what the scale does with individual grains of powder. I have no less than 6 groups all like this, today I had 3 touching at 200 yards with the 41.5, and the same a few weeks ago.

What would you look at for what could be cause constant flyers on what 3 out of 5 shoot great. All brass is once or twice fired hornady.

Assuming the barrel heating up or touching the stock isn't an issue (or loose screws), and the scope is good and set up properly, check the ammo.

Are your cases the same? If you want to be anal about it, make sure the cases are the same manufacturer, trim them to the same length, and weigh them. Use brass that weighs the same within 3gr or so.

After that, maybe looking at neck tension or ogive height.

wind?

Barrel heat?
I had a thinner profile barrel that shot amazing groups, until the 4th or 5th round.

How long are you letting it cool between shots and groups?

All cases are hornady and from the same lot.

Its a heavy barrel and only getting warm to the touch, 5 rounds every 5 to 10 mins. It has the magpul american hunter stock, so the barrel is not touching. It does have 2 bedding blocks it secures by, I will put it out of the stock and reinstall. Scope is tight.

The above is why I was thinking ammo related, all though the factory ammo tends to do the same thing, 2 out of three touching at 200 and the third 1/2 of an inch away from the first two. I have not fired 5 round groups with the factory ammo but once, and all 5 where under an inch at 200.