GunCat

Part #8 https://gunrepaircenter.com/versa-max-action-spring-tube-snap-ring/ Part #4 https://gunrepaircenter.com/F401319/ "Gun Repair Center (dot) com" is the parts supplier for newest iteration of Remington/ Rem Arms

Invictus Practical has a variety of chest rigs

Something is amiss. Once the shell clears the front of the latch it should not matter if you push it 1.00” or .001” more. Clearance is clearance. Does the front end of the shell lifter contact the latch when loading?

With an empty chamber and bolt closed slide one shell into the tube, making sure the shell rim is forward of the shell latch. Will the latch move over under its spring pressure (toward the center line of the receiver) and hold that shell in the tube? Can you move that shell in the magazine tube side to side and get it the slip past the latch and back in to the receiver?

Was the gun working properly, then started doing this? Without pushing the drop lever (silver tab) if you cycle the bolt by hand does the shell lifter move up/down as it should to bring a shell up toward the chamber? Does the bolt lock in to this “halfway forward” position when you fire the last shell in the gun? Or just when cycling by hand?

Have a properly equipped machinist or gunsmith turn a steel plug to just under the mag tube's ID, but larger than the follower's OD. Slightly taper each end of the plug. Clean then oil the inside of your dented mag tube then tap the plug through the tube to remove the dents.

Some info from Carlson that might help. (Near the bottom of this page)

I've been to several of the Generation 3 Gun matches at Gadsen, you could drive to every stage. I would expect the shotgun match layout to be similar.

Mossberg Accu-choke tubes (used in the 500,590,930,940) are interchangeable with Browning Invector (but not Invector PLUS) and Win-Choke.

Drill / tap the top of the receiver to attach one of the DPP mounting plates made for the Marlin 336 lever action rifle or similar. The mounting plate has a flat underside that is not too thick. Here's one example of the mounting plate

Can you source a Benelli M2 or Super Black Eagle inertia spring? That spring will work in your Stoeger M3000.

If you want to use the original pad trim the lugs so the recoil pad will fit back into the stock, then “grind to fit” the exterior of the pad to match the lines of the (now smaller) stock. Any well equipped gunsmith can handle this, its not too much different that than fitting a new oversize recoil pad.

I expect C-Rums can help https://c-rums.com/speciality-work

If you can have the Compass barrel threaded 1/2-28 (which should provide a suitable shoulder) you can use this adapter: https://www.silencershop.com/1-2-28-to-5-8-24-adapter-cnc-warrior-2.html

Is the magazine tube bushing in place on your gun? It is the first part to go onto the magazine tube when reassembling the recoil spring, bolt, etc - fits between the spring and receiver. I've seen a gun or 2 without the bushing (probably lost in disassemble) and the bolt bounce issue was increased.