Re: Help on barrel selection
I shoot the 240 gr Sierras in a Krieger 1-10 twist that I have on my 300 wby heavy gun and it simply shoots great (even at a relatively low velocity of roughly 2800fps). Originally I was facing the same dilemma and was about to order a 1-9 twist, but my gunsmith, who has been shooting and building bench guns around this combination for years, said he had never had a problem with the 10 twist stabilizing the bullets and thus convinced me to go in this direction.
I know Sierra recommends a 1-9 twist for these bullets, but based on my experience of shooting thousands of the 240ís, and the fact that you are primarily planning on shooting the 220 class bullets, I would definitely stick with the 10 twist.
Hope this helps!