Finn M39 Barrels

Which are the most accurate of the m39 rifles. I keep reading that the B barrel and Tikka made ones are, but wanted to see what people know about them. I know in general they are all very accurate but wanted to know which barrels tend to be the best?

Don't know about barrels, as we've learned that making sure that there's upward fore end pressure makes a HUGE difference in accuracy. Enough to mask minor barrel quality differences to be sure.

How so? Shims under the barrel?