Well, as I think I'm coming in late on this; assuming everything is assembled and tightened down as per factory, there is no way to change that spring compression and affect that gap. Per posts going back a couple of years, different color and thickness springs are dedicated to respective barrels. Just getting it back together can be a challenge. There is one possibility, for test purposes only, metal tape over a small portion of the holes. Say 25%. The metal tape I'm referring to is used in AC/Heating duct work. It wont last too long, but would work for testing. Cycling problems are usually due to low powered ammo or mechanical condition, i.e. drag, dirt, lube (too much or not enough). I cleaned, polished, and lubed mine a half a dozen times before it functioned reliably and hand cycling doesn't work to judge function. It likes brisk operation.