Guys, I have never built a rifle that short stroked due to shortening the barrel, and I have done more of these rifles than I can count.
It is situations like this that led me to start my business. This issue is being caused by something else.
So, it could be the barrel has an undersize gas port, no way to know unless properly guaged.
It could be a combination of undersize piston in oversize gas cylinder, again proper guaging tools must be used
Or it could be the gas assembly is too loose on the barrel at the gas port location
Or it could be one of several things. Unrelated to the gas system such as binding.
This work was performed at Dlask? If so, nothing would have been removed from the rifle ie: oprod guide, joe cuts and crowns with everything intact.
I'll tell you what Gas Can. You cover shipping both ways and I'll inspect your rifle for free just this once. I'm curiuos.