Originally Posted by
Sundo
I appreciate all of the informative responses.
FYI, I am trying to choose between two otherwise very similar off-the-shelf rifles. I am NOT putting together a custom rifle, so "choosing the best [custom] barrel" is not an option. The only option I'm giving myself is choosing between a 16" barrel or an 18" barrel, with a mid-length gas system, on an otherwise identical rifle design.
Even though a DI system has no moving mechanical parts, I was wondering if the diversion of the gas itself might disturb the barrel harmonics and timing, and thus affect shot accuracy. Judging by the nice groups that are presented from a 24" barrel, rifle length gas system rifle, that is not necessarily the case. Is that because the DI gas operation has negligible effect on barrel harmonics/timing, or is it because the DI gas operation effect is consistent enough that the disturbance is the same every time, imparting a consistent effect on the bullet?
How much more significant does the match between barrel length and gas system length become if a gas-piston operating system is used? If the piston's movement doesn't start until after the bullet has left the barrel, will there be any effect at all?