I would agree with that as well. My DI's shoot better groups. Hell, the LMT MWS I shoot most of the time shoots better than my AXSR.I gotcha. Im sure that’s right given the pressure increases. The difference in fouling of piston/DI is simply amplified using a can.
I still feel like my DI guns hold better groups than my piston guns, but they do require more maintenance.
That said, I did shoot 5 groups out of a 14.5 LMT MRP piston gun and all of them were sub-moa with match ammo. It was a surprise. the same gun with a 16" piston barrel shot 3" on a good day.
I would love to see a test some day of some fantastic barrel that was just swapped between piston and DI setups to see how much of the delta was related to barrel quality.