I just finished a Disco carbine build. It has a RJ breech, 14" barrel, full shroud, weighs 5.5 lbs with scope and is 35" overall length. I am getting 25 good shots with CPH at about 810 fps. 16 shots in the sweet spot have less than 20 fps extreme spread. Next I will be adding a HDD. I sighted it in and its first shot in the field dispatched a squirrel stealing strawberries from my patch.
You can easily remove the gauge "extender and then screw the gauge directly into the "thimble" in the airtube. Makes the gauge nice and compact to the airtube.
That's near what I use the most when hunting.