DG and others: I would direct you to my thread "What I did to my Shotguns" which covers lots of this information and more. Hopefully it will be a "Sticky" Soon so we can reference it more often?
First Buckshot of any kind is a 50 yard proposition at best. And that is with a Vang Comped Barrel. I have several barrels done this way and they all shoot Regular 00 Buckshot into 7" at 25 yards. This means it will still be viable at 50 yards but not much farther. You really need to be shooting slugs beyond about 30 yards because a Cylinder Bore Barrel is going to pattern 9 pellets at 30" which is kind of sparse for any effective use on just about anything.
There is a Drill that you need to learn: It is called the "Select Slug Drill." This is where you have buckshot or birdshot loaded in your gun and a Target Presents itself beyond 50 yards. You want to take the shot but know that what is loaded in the gun ain't gonna work, so you must load a Slug Round into the magazine and then Cycle the Action. On a Pump that means running the slide, or on a S/A Racking the Bolt. You should be able to do this maneuver in less than 5 seconds including making the shot. It actually takes a little practice and being able to manipulate the rounds is the biggest part of the transition.(Covered in detail in my thread)
The Vang Comp system consists of Lengthening the Forcing Cone to 3" then Back Boring the Barrel to .740-.745. The first 2" of the reamer are tapered back down to .730, so you essentially have an IC/Mod Choke working at teh muzzle. There is also 62ea. 1/16" holes on either side of the Front Sight which "Bleed Off Pressure" behind the payload so that it is not being Crammed into the choke under full Pressure. It is essentially "Coasting thru the Choke," and all of these features work together to reduce "Perceived Recoil." And It really does work!!!
www.vangcomp.com
I can shoot my guns all day long with nothing more than a Tee Shirt between me and the gun.
The other alternative for increasing range on Buckshot loads is "Federal Flight Control Ammo" (if you can find it?) it has been proven to extend the range by as much as 100%.
What they were thinking about with the big spring, was what is known as "Riding the Recoil." When the hammer drops, the Bolt Release is disengaged and the bolt is free to move to the rear. Luckily the payload is gone in Milli-Seconds. but the only thing holding the bolt closed is your hand on the Fore End.
If you have rearward pressure on the slide you can get ahead of the game and the bolt will open much faster, and then running it closed and chucking up the next round happens much faster. Also in the event that your magazine is empty and you have to Single Load the gun thru the Ejection Port, it opens the action much faster and ejects the spent round with more authority, then you put another round into the Ejection Port by going under the receiver and then slide your support hand forward to close the action and fire again Repeat as fast as you can. I just did 26 rounds in a 3 gun shotgun stage in 129 seconds with 20 single loads. It was much faster than trying to reload the magazine 5 times. Average Split time was 4.96 seconds per shot, and I was getting pretty tired by about shot #20! Last shot was a Slug thru a 3" hole at 30 yards and I made that one too!
Hope this helps some but there is a lot to operating a Combat Shotgun Effectively and it all takes practice after you are shown what to do. All my Training came from Front Sight, which unfortunately is now gone, and the new owners don't have a clue!
Randy