A .050” hole in the barrel reduces MV about 4% at the test conditions. There is a surprisingly energetic blast of gas coming out of the hole.
The .050” was a WAG. A larger hole in the barrel would make for a larger MV reduction.
A .050” hole has an area of ~ .002 in^2, so .002 in^2 ~ 4% MV reduction,
an .062” hole ~ .003 in^2, ~ 6% MV reduction,
an .093” hole ~ .007 in^2, ~ 14% MV reduction.
The point is, that drilling a hole in the barrel and then varying the effective hole size with a valve or a through-hole plug allows us to vary MV over a range.
A .093” hole drilled through the barrel, a large tapped hole centered in the same hole, and a screw with a through hole .050” dia would ~ 4% MV reduction.
A through hole of .062” dia ~ 6% MV reduction,
A through hole of .093” dia ~ 14% reduction.
Or an adjustable valve would allow a range of adjustment.
We are working with a Ruger 10-22 barrel and making a valve. The 10-22 barrel is easily switched, 22rf is easy, cheap and many flavors are available.
And, we’re still looking to see if a valve will tame the high MV fliers.