You could try it without turning and see if it works. Even if you have to turn, it’s only once and then you have a quality case that will last multiple firings.
I think so, I have only done a five shot group to confirm my load, and then put a harvest on it, then shot that group the next season. I’ve shot 190 ABLR out of it which I forget what the load was, but they were hitting sub-moa out of the gate.
No experience, but from QL with a 134gr Hammer 22" barrel, case fill < 110%, pressure < 62,000psi:
RL16: 37.5-42 (42 = ~2871)
Hunter: 40-44 (44 = ~2841)
Varget: 34.5-38.5 (38.5 = ~2753)
I don't think your 4831SC load is all that far off on velocity, 20-60fps. What were your other loads and what speeds were you getting them. The 7828scc should be getting you another 100fps. Might want to give Ramshot Magum or N560 a try as well. Could be your barrel is just waiting to speed up.
I think more importantly, get a couple of calibration rods in different lengths, a longer and shorter one. That way if your calipers are off, you will know.
Lower end of the price range like so: https://www.amazon.com/Calibration-Professional-Micrometer-Calibrating-Micrometers/dp/B08K3KN9NP.
Older article called “MELs, Moderate Effective Loads” in Hogdon 2009 paper manual has four loads for that combination with 4198 and 4895, both H & I, that were running around 2,730fps muzzle velocity. Recoil ftlbs ~8-10lbs. Barnes has the minimum impact velocity at 1700fps, but you should be...