Anyone have any idea where I can find a Benelli Supernova or MR1 5 Position Recoil Tube?

This:  https://www.benelliparts.net/store/p11/Benelli_Supernova_or_MR1_5_Position_Recoil_Tube.html


Though it hasn't been in stock for years, there.  I think this may be the same part:


https://www.gunpartscorp.com/products/1459560


Though not ever in stock there either.

You may be able to use a Benelli M4 recoil tube. The Benelli M4 is threaded M21x1, and I think the SuperNova may be threaded the same.

Unfortunately the Benelli M4 stock is not compatible with the M3 from the research I've done.  That would have been my first choice.

Up until recently, those 5 position recoil tubes were available at the usual Benelli sources. FFT (Freedom Fighter Tactical) had one a few months ago, you might try calling them? They had it listed as an option for the Benelli M4. It would only work if you used the Supernova collapsible stock.

@jbt33

One of these two should be what you need Midwest Gun Works

If you have the later serial number range I bet a M4 recoil tube would work, the M4 furniture just won't have a seemless fit. From my experience, a lot of Beretta and Benelli shotguns share the same overall engineering with just a slight modification between models.

For example, the handguard and stock from a Beretta 1200F will fit on a Beretta Vitoria/Pintail/ES100. The Vitoria is also almost identical to the Benelli 121 M1, except the mag tubes and mag tube attachment on the barrels are different. My guess is that a Beretta 1200FP mag tube will interchange with an 121 M1. The Bolt carrier from a Beretta 1200 will also interchange with a Benelli M1. The very early M1s also share the same thread pitch for recoil tube and mag tube as the 1200, and the early middle M1s still share the same recoil tube threads.

Thank you.  Since mine is a very early M3, I gambled and bought this one:  https://www.midwestgunworks.com/page/mgwi/prod/61364

I already have the stock kit here:  https://www.midwestgunworks.com/page/mgwi/prod/61171

I did have to modify the inside of the pistol grip a bit so that it will fit flush against the rear of the receiver.  There isn't much info online about the M3 and this modification, but I read about removing the 'dummy' recoil tubes on Benelli's and was prepared for a battle.  It really wasn't bad at all.  A heat gun for 3 minutes and a screwdriver to get some leverage in the drain hole at the end to twist it off and it worked.  

The grip only needed minor modifications to get it to allow the rear end of the trigger guard to fit inside it, as the trigger guard extends about 3/4" past the end of the receiver.

My recoil tube should arrive tomorrow or Tuesday and if that's the right one, I should be good to go.  I did see that Benelli does now sell this shotgun to LE in this configuration, so you can find them on Gunbroker - but they are the ones with the ghost ring sights.  Mine has the early rifle sights, so a rare-bird this one will be.

Ugh.  The one I bought didn't fit - the circumference of the threaded portion was too big.  So I RMA'ed it and paid the restock fee, then ordered the OTHER one and just got it today:  same issue!  

Are the early Benelli M3 receiver extensions different than later model M3's?

My guess is that your receiver threads are M19x1, whereas all the new stuff is M21x1 as far as I've been able to find. I rethreaded my Beretta 1200 receiver from M19x1 to M21x1. It doable with hand tools, but I came this close to screwing it up.

Wouldn't it be safer and possibly easier to reduce a portion of the threaded receiver tube from 21x1.0 to 19x1.0 and leave a step-up to 21x1.0 to allow the pistol grip to screw onto it?

Oh definitely

Yes, and it's my understanding the only one that will accept the collapsible stock is the model # 11608 M3. If you look at the receiver profile on this one, it is the same as the M2. The older M3 models have the same receiver profile as the M1. They are essentially the same guns but have some minor variations like the thread sizes.