Don't use a vacuum, even a cordless variety. Air being drawn across multiple dissimilar surfaces, toss a little powder in the mix, and you know...
Load ladders and groups....start at 300 yards.
I use 204 Ruger headstamped brass and neck up.
Cheaper than 222 Magnum brass AND...you can find 204 Ruger brass.
JB Weld a threaded bolt inside the remainder of the case. Let dry overnight.
Scratch the inside of the case for the epoxy to grab.
I have not shot enough AI rounds thru two different options available to me, to say barrel life is extended.
My equipment may not tell the truth,...
Clean and apply a light coating of pure or 100% silicone spray. (MUST say pure or 100%, otherwise, there are petroleum or other additives).
Hodgdon HS6 - clean, very accurate, at or near top velocity, double charge results in powder spilling over, and works rather well with...
Are chambering parent cartridges or previously fireformed cases from this chamber?
Don't take this the wrong way, but sometimes, a non normal approach to VERY unique situations, is needed.
Adaptive shooting techniques.
How are the 300 yard groups?
Price your components.
GOOD or GREAT brass:
x284, IF you can find, is expensive. ($1.24 per piece, Winchester - I just used some googlefoo!)...
H4895 always seems to be a little more accurate (with good speed) as the others you are using.
In MY barrel, 25.0 of H4895 with 69 gr SMK's is nothing short of superb.
GOOD set of shooting sticks (mono, bipod, or tripod) that are lightweight.
Depends on the brass manufacturer. Some run the standard US casehead size and some use the metric flavor.
Lapua brass readily available.
Long action allows the bullets to be seated to take advantage of the case length.
Have been in the same predicament.
Believe it or not, my 1.xx MOA 100 yard groups, were 1.0 MOA at 300.
At what distance are you completing your load development at? Truth begins at 300. :)
Separate names with a comma.