243 Winchester 1:10 twist long range load

So I have a rem 700 I picked up for a decent price that was rebarreled with Mountain Rifle Co. barrel with standard 243 1:10 saami spec. Med weight barrel, magpul stock, 2.5# trigger, vortex viper pst 4-16x50. Thought it was gonna be a great hunting gun, as I've only heard great things about the .243. Well, about 300 rounds into load development, I was giving it another 100 rounds before it went down the road it was so bad. Tried 6 different powders. Nosler 95s, 105 a-max, 95 sst, and 90 eld-x. Was getting desperate! Some groups were ok, especially for a mid range hunting gun, but most groups looked like a shotgun pattern. Finally did some more research and thought I'd try the Berger 95 classic hunters. And as mentioned above, the Berger stability calculator does show as not stable and box does mention 1:9 recommended. Well, almost all groups with a few different powders were better than anything else. Ended up with 42.0 gr of H4350, seated at 2.25" bto (.015 jump), hornady brass, 210, annealed with .002 neck tension, 3030 fps avg. Shoots consistently if I do my part.
Took this to my first PRS match and placed 12/24. Think I'm gonna keep it. See attached pic, 5-shot 200 yd group.

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I've used the 100 grain Hornady Interlocks in a 1:10 with great results. Haven't shot anything with a .243 greater than 250 yards though.
 
Nosler AB...thats not bad, anyone try the Swift Scirocco?
I've found the Scirocco performs better than the Nosler AB, but only slightly. And the fact that for quite a while the Swift's were hard to find I settled on the Noslers only because they were more readily available.
 
Looking to stretch out the 243 with a standard twist. Ordered some Lapua Brass and have Fed 210m primers on hand, plenty of powder, but what bullet really takes advantage to hang the energy out there? I know its not a long range hitter (have a 257 Bee and a 300 Win Mag) but what loading combo would potentialize the 243 Winchester ??
My Remington seems to like factory Federal 75 grain better than anything else, (at least so far).
 
I've been trying to make this work in my Rem700 Varmint 1 in 10" 243 for several years now. I shoot at about 4800 feet altitude out beyond 1000 yards. 100s, 95s work OK out to about 800 yards, but fall apart (tumble) beyond that. I use 2x4s to support steel targets and often find the 243s keyholed in the 2x4s past 800.

If you are intent on using your 1/10 243 for long range, try a good bullet in the 85 - 90 gr. range, don't worry about BC, and keep it as fast as is possible with accuracy.

Myself, I've given up and decided to rebarrel the 243 in a 1/7.5 remage and use something like the Berger 109s for long distance (if they ever become available again).
 
It is slim pickin's out there for sure. I was at two Cabelas and two gun stores in the last 24 hours the only 6mm bullets they had were over 100 grains. And two boxes of 80 grain Barnes TTSX, not sure about these though.
 
I like the 85gr. Sierras alot, but past 300yds. I go for the Sierra GK 100 btsp at about 2990fps in a factory Remington, not sure of the twist difference.
 
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