Steve Rose

KalashNova, What is the outside diameter of your barrel at the muzzle? Use a caliper or micrometer to measure to 3 decimal places. Knowing that measurement I can give you some idea of choke tube installation options. (This question looks familiar. Did you and I discuss this on a FB forum within the past week or 2?)

3mm x .5 (metric)

If loose the barrel extension can unscrew off the barrel. I've seen maybe 2 or 3 barrel extension get loose over many years. Take the extension off, clean/degrease both thread areas and apply some red Loctite to the threads before screwing it all back together. It should stay put

On the Brownells schematic and parts # listing the cap retaining pin and spring are the same on the M2, M4 and Super Black Eagle. No mention of a “sleeve” (I still think the retaining pin is staked in place)

This is a M2 barrel

I bet the 870 detent staking tool would do the job. I think I have one around the shop....somewhere https://www.brownells.com/gunsmith-tools-supplies/shotgun-tools/staking-tools/870-detent-staking-punch-prod25277.aspx An automatic center punch would work in a pinch. A third hand to hold the detest and spring in place while upsetting the metal would help.

True, the older guns came out with a cast link that would occasionally break, same with the original Super Black Eagle (I've seen 4-5 broken parts over the years). Probably why the part was redesigned to use 3 sandwiched/rivets steel flat sections.

The standard Nordic +5 tube(see below) is just a bit longer than the 21” barrel. Nordic also lists a +5B that is advertised as being a match to the 21” Benelli M2 barrel length. The standard 5 tune is 11.60” long, the +5B is 10.83” long. Nordic tube lenght info Some barrel clamps can impart pressure on the barrel and affect POI. There are methods for installing in the Nordic clap that can negate the clamp's affect or MOA Precision makes a “free floating” clamp that does not affect the POI. MOA Precision clamp

Well....here's a different kind, one I finished up earlier this year:

The bolt release is In stock on August 14 Link to MOA bolt release

Yes, that is a TTI safety.

If you dry fire the gun (empty chamber) will the action open easily? If it does open, try a dry fire with a little backwards pressure on the forearm to see the action still opens. We are checking to see if the Bolt Latch is disengaging when the hammer falls. Does the interior of the chamber feels smooth with no rust or plastic buildup?

What brand and type of ammo are you using when the problem occurs? If it is the Winchester "Universal" or their similar promo ammo (silver metal rims, ribbed red plastic hull) its an ammo problem.

Has it always had this problem, or did it start after some period of working well? Which brand and type of shells are you using ? What is the shell's velocity and shot weight? Have you ever removed and checked the inertia spring inside the bolt carrier? (There was a run of Stoeger inertia springs a few years ago that would break)

The NFA/ATF no longer requires a CLEO sign off (as of July 2016) ...but it does not matter in this case. As far as I know New York does not allow Short Barrel Shotguns (less than 18" barrel) https://www.nationalguntrusts.com/blogs/nfa-gun-trust-atf-information-database-blog/new-york-state-nfa-rules-and-allowable-nfa-items

On the 1301 the lifter drops when the hammer falls. What makes the lifter drop on your Benelli mod?...or just go shoot it, I want to see it work! ?

Yep, the hinged 20ga latch holds the shell just a bit father forward than a 12 ga latch (and can contact some followers)...and don't try to drill & tap the 20ga latch for an oversize release button.

Can you go directly from loading the mag tube to shooting, or do you have to pull the bolt back to get the lifter to drop first?

M4 factory barrel. (The short M1 barrels are quite a bit thinner)

The Nova follower is stepped down in diameter. The M2 follower is not - so it will not travel to the end of the mag tube on the last shot (lacks about 5/8”). You'll have to go to Nordic or RCI/Roth Performance for a metal Nova follower.

We (Rose Action Sports) have threaded several of the short factory barrels for Rem-Choke or Mossberg Accu-choke tubes.

Are you sure the width of the hammer is the issue? A hammer disconnector hook that is too tall can hold the hammer back like the picture you posted – but you will NOT be able to pull the hammer back up the correct position after cocking the hammer. If you CAN pull the hammer up into the correct “cocked” position then the “too wide” diagnosis is probably the right one. Coat the hammer with a black or blue Sharpie marker then install it. Functioning the hammer a few cycles will wear the marker color and show you where any contact is occurring.

Compare your gun's hole spacing to this (picture from the EGW web site): Scope base hole spacing for the Benelli scope base (same as a Weaver 93)

@Jimbo45 Was that a M1 barrel, or M4 barrel ?

It is really just an extended and ported choke tube with wicked looking teeth on the end. The “no slugs” comes from it being an “Extra Full” constriction. Carlson also marketed a Cylinder constriction tube in the same style that was OK with any shell type. Both are showing "out of stock" at Brownells and Carlsons