Re: results of barrel setback and rechamber
"The load is a bit hot." No kiddin... 25" barrel, >3000fps 30 cal 200gr. I'd say perhaps just a little past hot.
I would say if you brought the same load down below 2800 to say just over 2700, it'd shoot terrific. If you don't think it has enough snot to kill something at 5-800 yds, just stand out in the field and have someone shoot you with it and tell em if it hurts or not.
I don't know what barrel diameter you're shooting or how the gun is set up (stock/rest/etc) and I don't want to discourage you. Different setups are designed for different applications and one is not necessarilly right for the other, but, if my 16# gun shoot's a 10 shot 3" group at 400 I'm gonna tear it down and fix something. It's a last place gun at williamsport (reference the standings). I'm taking a little of my own advice this weekend on my 6.5 and SLOWING DOWN. I shoot my 30 cal W/210 at <2800 with a 28.5" barrel and barely a 2" case, (barrel is used for acceleration, not case holder). My guess would be that of the shooters w/30cals and <=30" barrel, 80% shoot under 2850fps and 100% of those who win shoot under 2850fps. I would guess that your gun that shoots 5" at 500 will not keep 10 on a 42x62" target at 1K as my 6.5 that shoots <3" (too fast) at 400 cannot keep 10 in 2feet at 1000. Lots of things happen out there past 500.
Everyone's been there, thinking "this is great", the moral of the story is, it'll do better with some work.
PS, I'd have stuck with the shot out throat and worked with it. Glad to see it improved for ya. Try 66-68gr H1000/R25 just for kicks. Bet it shoots better...
If you have something that you disassemble and reassemble enough times, sooner or later, you'll have two!