Steve Rose

Can't give you a specific without knowing which shim your gun has now...but changing to a shim that INCREASES the stock “drop” will help your move your POI lower. Even with the max drop shim installed the SBE3 is still probably going to shoot a pattern that is 70-80% high, that is just the way the gun is designed.

Briley has a similar forearm available

If you can increase the drop and add left cast by changing shims that will help bring the POI down and to the left. The butt of the stock is like a rear sight, you move the butt (or rear sight) the direction you want the POI to move.

You are on the right track with your methods. You can also hold the drop lever up, cycle the bolt continuously (while continuing to hold the drop lever up) , no need to press the lever for each shell in the magazine.

The cartridge drop lever sure helps in unloading the magazine tube when you want to empty the shot shells out of the gun (without pulling the trigger). The Italians will probably tell us American we've been design guns wrong for all these years ? (glad to see you are still checking in here 5 years later too? )

Pressing the button and allowing a shell into the action did not cause your gun to “click”. If a shell was in the chamber your gun's bolt was slightly open / out of battery (look up “Benelli click”) or you had a dud shell. You can press the button (aka “cartridge drop lever”) placing a shell onto the lifter when gun I cocked and a shell in the chamber with no adverse affect. Its similar to “ghost loading” the Benelli.

Midwest Gun Works Carlson's aftermarket barrels

The Salient bolt release button is the Arredondo part, available from several sources (requires drilling and tapping your gun's bolt release). The Agency Arms looks to be a custom part.

The bead will unscrew. You might need to using a little heat (soldering iron) to loosen Loctite. Parallel jaw pliers or a Machinist clamp works well on the fiber optic front bead. The mid bead can be a pain to get out without any damage given the really small head that wants to be held with vise grips (if you do not have a little pin vise) to remove, just replace it if needed.

Yes. The SBE2 and SBE3 bolts are same with the exception of the “anti Benelli click” parts added to the SBE3 bolt body and bolt head. Some of the 3 Gun guys have been using the Ethos bolt in the M2 for the same purpose (the Ethos bolt has the same “anti click” design)

You can move the back end of that HiViz to the left if it helps you (you only see the end of the fiber bead with the gun shouldered) - but the best practice when shooting moving targets is to focus your eyes on the target, not the bead (in other words....don't look at the front bead when shooting)

The adjustable rear sight is specific to the SLUG BARREL

If the M2 is available in the configuration you want (and 3.5” shells is not part of your list) then there is no good reason to go for the SBE3. The SBE3 does pattern high, the M2 shoots a more traditional pattern right down the rib

"Mobil" choke tubes for the SBE 1

Wildwest22's barrel is OK. As others have stated the barrel is manufactured in that design to allow adequate metal thickness for the screw in choke tube. I've seen several “bulged” barrels caused by obstructions, i.e. mud, wads, choke tubes not screwed in completely, etc. This is not one of them.

Right and left Benelli barrels are not interchangeable. The ejector and extractor cut are on opposite sides of the barrels.

No sling mount on the Nordic. You can add a tube/barrel clamp with a sling stud, rail or QD - or put a loop of para cord around the tube for sling attachment.

Noveske and Grovtec make QD sockets that fit into a 1/2” hole in the stock and have a nut on the inside of the stock

Roth Performance used to make a Monotube for the Vinci, but they were discontinued around 2018. You might find one on the 2nd hand market. The Vinci tube magtube is more involved given its forearm/barrel connection. They are going to be more pricey than a standard extension tube for other models.

Factory size is 8-40

https://www.midwestgunworks.com/benelli-828u/forend-adjusting-screw.html

Is the trigger housing damaged and allowing the CSP to move out of place? This after market CSP is better materiel than the factory part (but it will not help if the spot in the trigger housing the CSP resides in is damaged.)

Does the hammer fall with significant force/speed when you take the trigger group out of the gun and hold it in hand for testing? Was this a one time occurrence? or does it "click" on a majority of shells now?

If this was a gun with an extended magazine tube I would tell you the magazine spring it too short/too weak – the last round coming out of the tube does not get pushed all the way back into the action....but since its a factory length tube something else may be the problem....but I would try a new magazine tube spring first, and make sure the plug is installed properly and not binding up the spring. When reassembling the magazine parts: Follower > spring > plug (with big end toward the muzzle) > spring cap

Start with Improved Cylinder for traditional buckshot shells (some loads might pattern better with Modified, but IC generally works well). If your Buckshot loads has a Flite Control wad use Improved Cylinder or Cylinder (no constriction). Anything tighter will degrade the pattern.