First unless the brass was fired in that rifle, you should full-length size it. Neck-size only if/when that brass is staying exclusively with that launcher, otherwise you are creating potential for pressure signs. Granted some of those signs MIGHT be false readings if the bolt is hard to close, but IMO this is not the caliber to get too frisky with!
Second, yep you probably have either pressure issues or a bad fit in the chamber...head spacing? Better back off that load by reducing powder charges. In this cartridge, I have no doubt you can tighten that group up but if those primers keep doing that I recommend a trip to a gunsmith for a check on your headspace. Also - make sure that chamber is REALLY getting cleaned all the way. At typical RUM pressures it doesn't take much "varnish" build-up in the chamber to start screwing with your headspace, and then reading pressure signs gets tricky.
Third, a question - what other bullets/bullet weights are you planning to try with this rifle? I have not spent time with the 230 bergers in this cartridge, but would like to share this thought - decent 190-200 grain pills are devastating on elk, with 1/2 MOA accuracy out to 500+ yds when I launch them at about 3200 FPS. No pressure signs when doing this therefore I'm comfortable saying that I'm not wrecking my brass either! Note that I use this caliber to hunt, not shoot 1000 yard competition...so if that's a serious consideration disregard and concentrate on the heavier pills.