I've done a little research and it seems like I could buy a Mossberg 835 barrel that could be used on an existing Moss 590 that I own. This would give me added capability without having to buy a new gun. The two caveats I've found are that the 835 barrels have a 3.5" chamber but the Moss 590 receivers have a smaller chamber (2 3/4" I think). I think this is okay as long as I only shoot 2 3/4" shells. The second caveat is price. It seems like trying to buy an 835 barrel is almost as expensive as buying a complete 835. That's if you buy it new direct from Mossberg or Brownells. It can be cheaper on the secondary market like eBay but I couldn't find the barrel I think I want (28" Vent Rib non-ported). All of the barrels on eBay I've seen have been ported.
I have never been hunting nor shot skeet. I might eventually do both and since I already have a few Moss 590s in my collection, it seems reasonable to add an 835 barrel so if the opportunity arises where a friend invites me, I don't have to try to scramble at the last minute. There's just too much that I don't know and need help with the decision.
Given the price of the barrel is so close to the full gun, the first advice might be "just buy a whole 835" but the reason I want to avoid that is because it's a bit of a hassle to go to the FFL versus direct ship a barrel, gun safe space restrictions on adding a whole new gun, the desire to not have to drop another $200 between Magpul furniture, upgraded steel safety, upgraded follower, upgraded mag spring.
However, one idea that came to mind is buying a full 835 and stripping it down. I throw out or give away the factory furniture. I take the barrel for my purposes. I separate out the mag tube as a spare for one of my 590s. And I keep the receiver in my gun safe as a spare. I did plan to buy a spare trigger assembly to have on hand for my existing 3 Moss 590s because I like spare parts. But I want a metal assembly and I imagine these will be plastic.
If I go this route, maybe I actually swap the 835 receiver for one of my 590 receivers. The 590 receiver becomes the "spare part" and the 835 becomes the main receiver for my 18.5" shotgun. Then when I swap the 835 barrel on there, I could use 3.5" shells. I'm not sure if putting an 18.5" barrel set for 2 3/4" shells in the 3.5" receiver will be a problem as long as I only use 2 3/4" shells with the 18.5" barrel.
Here's what I don't know and need help with:
A) How important and useful are shooting 3.5" shells to hunting? Is it goofy for my only hunting shotgun to be limited to 2 3/4" shells because I'm using an 835 barrel on a 590 receiver?
B) If I buy a whole 835 and "convert" it into an 18.5" 590 for daily use, any problems shooting 2 3/4" shells through the 3.5" reciever? Less reliable or sloppy?
C) Can I get away with a single "hunting" Barrel to expand my capability? If so is the 28" Vent Rib Non-Ported my best bet? If not, which barrels so I need to add? I have 14, 18.5 and 20" currently.
D) Do I need to consider also adding a dedicated rifled slug barrel, or can my 20" smooth bore 590 barrel be good enough?
E) I run ghost ring sights front/rear on my 590s. If I put an 835 VR barrel on there, will it be weird to shoot looking through the rear ghost ring?
F) What if I kept the ghost ring rear sight on the 590 receiver and put the new micro S1 Aimpoint Vent Rib mounted optic directly on the 835 barrel. Would the rear Ghost Ring obsure the red dot?
I have more money than I have gun safe space and buying a new gun safe isn't an option for several years. I definitely will not purchase an 835 full gun and put that in the safe. I am open to buying a full 835 gun and stripping it if that's the most cost effective route and gives me an extra spare receiver or if making a franken 590 with 3.5" receiver makes sense for this project. The main limiting factor is reducing storage volume in the gun safe while expanding capabilities of my shotgun collection.
I'm aware of the magazine tube limitation and I think my 18.5" 590 (6 shot) has the same mag tube as the 835. I don't need to be able to interchange the 835 onto all three of my 590s. Or it might be that my 14" (5 shot) has same magazine as 835. I checked with ATF and I can put a >18" barrel on my 14" Short Barrel Shotgun and temporarily convert it to Title 2, and I have that in writing in an opinion letter. Not that I expect it to jack me up, because it would have a >18" barrel on it at the time any LE saw it, so they wouldn't even think to run it through NFA registry nor would they necessarily care.