I've never had or seen a "custom" action where the scope mount holes were not on the centerline. I've seen many Remington 700 actions where at least one was off center. This is not a reason, in itself, to choose "custom" over factory. Overall, any custom I've ever used or seen has been superior in 'straightness', fit, and uniformity to factory. When you 'true' a factory action what you are doing is refurbishing it, hopefully to better specs than it left the factory with. I believe the new 700s are made on multi axis CNC machining centers instead of moving the piece from jig to jig, machine to machine to completion. There's lots of room for errors when you have a human moving parts from jig to jig and having a time requirement on each operation, like the older ones were made. They are 'straighter'now than they've ever been, from what I've seen so far. The problem of 'fit' still comes into play. You have to have an after market bolt to get that 'custom fit'. The 'factory' is made to meet a price, something has to 'give' to meet that price. The 'custom' is made to meet a requirement. That requirement is precision without alteration. I think the question should be, "Can the average shooter see a difference in accuracy between a factory action, trued by a gunsmith, and custom action?".