Re: Flinching because of muzzle breaks
I can honestly say that I react more to muzzle blast than I do recoil. Of course that can be hard to prove cuz they often go together, but I have noticed that I shoot a bit better from an uncovered shooting position where blast is disbursed.
I suppose that live targets dictate differently than inanimate, but look at the cartridges that are really successful in long range target competition. The 6.5-284 is often the top of the rankings power-wise (along with the occasional 300 WM).
Personally, I've found that shooting my 6mm-250 is a TON of fun to shoot because of a lack of muzzle blast and it gets a ton more attention than the other rifles in my cabinet for that exact reason.
At any rate, I suppose that if I were trying to fire a 338 RUM from prone I'd feel differently, but at this point I see muzzle breaks as more of a liability than advantage because of my sensitivity to recoil. I've fired a 338 RUM several times from the bench and was surprised at how manageable it felt, but I've fired enough different rifles from the bench and then been shocked at how the change in geometry affects felt recoil when going prone to know that it is quite a different ballgame.
On the other hand, I'd not care at all to sit next to a partner shooting a RUM w/ a break. I gotta imagine that it'd SUCK no matter how many forms of hearing protection I'm wearing!