I’ve got a new build I’m trying to dial in.  It’s an AR10, 20”, 1-11, 308, Krieger barrel, LaRue trigger with a Viper 5-25 scope.. I did some research and selected about 8 proven loads.  I loaded ammo for each plus some factory Federal GMM 168gr.  I shoot 5, 5 shot groups to get a good sample.  The problem is my groups will be about 1 MOA with an occasional .4 or 2.0.  They will still a average around 1 MOA.  What I’m looking for is less then MOA all the time.  I want a consistently.  I reload but don’t have a Chrony.  What do you recommend I do?

I would pick a powder, bullet, brass, primer combo and run a tiered load to see what your barrel likes.

If 42 grains of powder X is a desired starting load, do .3 grain increments and load 5 rounds of each load.  This would be 42.0, 42.3, 42.6, 42.9, & 43.1.  Make sure your highest load doesn't exceed the safe load in the manual you are using.

Shoot one round in each of the five targets to distribute barrel heating.  In other words, shoot the first round of the first load in the first target.  Shoot the first round of the second load in the second target.  When you are done with your first five rounds, you then shoot the second round of the first load in the first target....

You will see accuracy nodes if you do this over a wide enough spectrum.  Hand weigh each powder charge on the load-up and take your time in case prep.

If they all look like garbage, try a different powder or bullet.

It is possible your barrel hasn't settled in yet and may take 200 or so rounds to start shooting more consistently.

Start with the big stuff first:

1) Check the barrel - is the crown clean, free of nicks/burrs?
2) Optic - scope firmly tight, all screws tight with threadlocker?
3) Barrel firmly seated in receiver, barrel nut properly torqued?
4) Have you had someone else shoot the rifle (preferably higher skill than you)?  Same result?

Move to the smaller stuff - your hold/rest, mechanics (trigger squeeze/breathing), flinching?  Can you take yourself out of the equation and shoot off a lead sled or similar?

Finally - loading variation - different loads/bullets perform better/worse?

IMHO, even a pimped-out, high quality AR10 is going to be hard-pressed to shoot <1 MOA.

My money is on a flinch.  Before you drive yourself nuts, have someone else shoot it.

I’m shooting 168 and 175gr SMKs.  I weigh each powder charge.  Barrel has 75 rounds through it.

Do they shrink and open vertically, horizontally, or diagonally?