From Sierra Web site.
Some baseline data for 142 Gr.
Sako S20 with a good scope should be shooting much better than that, even with ladder charges. You could be a grain or more off of powder at 100 and not be 'patterning' like that. Also those cold bore flyers are 'way' off where a Sako should print cold.
By way of comparison, my TRG will send a cold bore first shot 1/4" - 1/3" up and to the left consistently. No Sako worth its salt should be putting out a group like that at 100 even if you are mixing up all kinds of stuff.
Before going to a ladder charge, may I suggest loading a box of 50 at, say, 34 grains. Fire the whole box of 50 in groups of 5 at small dots. See what you get. If they are patterning or all over the place... check equipment and technique (both loading and shooting).
Your long range groups with (what I assume are factory rounds) are good. And should be indicative of what you and your rifle can do. I would suggest getting a baseline on your reloading technique with a decent sized batch of rounds. Then start working up and down from that baseline to get the group tighter.
But I think that jumping into reloading 'first' with ladder charging and changing up your recipe right out of the gate is just going to confuse you or frustrate you.
I know powder and primers and components are hard to get right now. But here is how I go about a load for a new rifle.
I pick out a 'decent' load with the bullet weight I want based on range and twist. I'll load about 20 rounds. And fire them just to inspect case, primer for flattening, figure out OAL/ogive seating, etc. I'll shoot those at 100 and expect a good, but not perfect group. If it's not a good group, I'll do another 20. I never go near maximum powder charges. I find that a bit on the slower side is better (then again, I rarely shoot at ELR)).
Then If those 20 check out, I'll load 500. I rarely load less than 500 at a time, except for exotic things like hunting loads for weird rifles. But those 500 cases cases will become 'matched' to that rifle. Those get fired out at all ranges. But are still not my 'final' rounds. I expect they will shoot well. But not as good as they 'can' be. But using those brass which are now fireformed to the rifle, I will work out my 'final' load. Using anywhere from 20 - 50 loads to refine the charge and also do all the 'scut work' like primer pocket stuff and neck stuff, etc. Then I'll load up 'all' my cases in my final load. In that case it's micrometer dies, primer pocket depth seater, all the bells and whistles. Then we're looking at real groups and consistency.
I find I get three shootings out of the brass before I want to FL-resize and trim. Might be time for annealing, too. But I generally just replace brass if it's something not exotic. I'm not into annealing. Not because I don't believe in it, just because replacing brass is easier.. So after a few reloadings my .308 (for examle) gets designated for beltfed loads or plinking.
But I would say you are jumping too fast into trying ladder charges and tinkering with the loads. Establish a baseline with your first handloads. Get a few hundred (at least) behind you before you start tinkering. Maybe try some different bullet weights for the 1:8 twist. But ladder charging is after you have a basic load worked out.
Your rifle, gear, etc. seem right on. Practice on your reloading to get technique and muscle memory (of loading) down and carry on!
Sirhr
