Under 400 I think it takes a radical dimensional deviation to show on the target. Definitely evident at 600. At a 1000 even mild deviations result in group break down. Just my opinion and the guide I use to make my bullet selection decisions. At 1000, I even don’t want to use rejects for my sighter rounds.
Your OAL range is not a “blemish”. That is very respectable even for hand pulled bullets. Bergers often run significantly over that - up in the 0.014 - 0.021 range for some lots. Sounds like you got a very good batch of bullets Grant. 👍
Caution is always the first priority and 1/2 MOA at 200 is a very acceptable load for pushing on out to 600+. No immediate need to go higher and you might wait until you have all your equipment available to make you feel more comfortable in finding the upper edge. However, neither velocity nor placement on target is a stand alone assessment of excessive pressure. Your Tikka action is a strong one. If you are seeing NO pressure signs at 44, then moving on up in 0.2 gr increments is not irrational. Just be willing to stop at the earliest sign of bolt ejector swipe or increased bolt lift. Primer deformation is not always a reliable indicator of over pressure.
Have you looked on Shooter Reference for the combo you are using?