Re: 300 ultra twist rate
As Shawn already stated, if you want to still shoot 180 gr bullets the 1-12 would be my choice as well. I have developed loads in 300 RUMs using the 200 gr Accubond in 1-12 barrels and accuracy was pretty good but I have never tested this bullet weight in this twist barrel at long range or in cold weather to be able to tell you for sure it will work in every situation with a 200 gr pill.
With a 180 gr though I would say you will be covered for every situation with good bullet stability.
I would personally look away from the Scirocco bullets personally. They are just to darn sticky being pure copper and from my load testing, the Nosler 180 gr Ballistic Tip and 180 gr Accubond generally shoot better groups on average and are less expensive as well.
Another bullet choice to look at would be the 178 gr Hornady A-max. This bullet is much thinner jacketed then any of the others we have been talking about and its tipped design will offer more violent expansion on lighter game.
What you need to realize if that these bullets are big and heavy. They simply take longer to expand at the velocity levels you can obtain then a 22-250 with a conventional bullet that is designed on purpose to come totally unglued on the lightest game.
The lighter bullets in the 300 RUM will certainly offer not POP value then the 180 class bullets but I have found accuracy to be sub par as you are also seeing.
TO be honest, if you want to build a rifle for hammering chucks and you want more power but still the same expansion level why not look at something like the 270 WSM loaded with the 110 gr V-Max to around 3400 fps or a bit more.
Just seems to me your choice of cartridge is really over powered for the job at hand and I think that is why you are seeing problems getting the results you want. Just to much of a compromise all around.
Another great choice would be the 6.5mm WSM with a 95 gr V-Max at 3500 fps.
Not trying to change your mind, just offering options that may get you much better results for what your looking to do.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Farther, Faster and Flatter then ever before.
Web Page: www.apsrifles.com