Yep, this is the problem with "faster is better" as relates to twist. At some point the bullets blow up in flight. We've even seen it with 1 in 8" twists in 6.5-.284 for some bullets. One promising theory is that melting of the lead just under the jacket plays a role so that keeping the barrel cooler and/or reducing barrel friction with coated bullets may help. This theory seems consistent with our observation that we've never seen blow ups in the first 10 shots from a cold barrel - always later. Lapua Scenars seem more resistant than SMKs and AMAX.