I would say before having it threaded, try the FliteControl. In my experience through the 20" guns, the FliteControl out performs Hornady's VersaTite.
Also, what load would you intend to use to dispatch critters, varmints, and predators? Federal Premium makes a number of FliteControl options these days in different sized shot including 3" loads. If your intended distance is about 40 yards and your gun is capable of delivering payload that far, your dollars may serve you better by simply investing in ammunition and then patterning to see what works best and puts pellets on point of aim.
Also, if FliteControl is working, I'd stay away from any sort of porting.
What sized varmints are you considering having to deal with?
There's a couple issues I have with using FliteControl;
- I use 2 3/4" steel shot for the garden/orchard that I got for $9/box. I don't want to contaminate the ground with cheap lead shot. There is steel shot in the FliteControl variety but it's over twice the price.
- Limited loads and limited availability. The sporting goods store near me has a wall of ammo about 1/8th of what Cabelas has. Their prices are high and the selection is low. Living in a rural area, I don't have big-brand stores like Cabelas. The Walmart near me has piss-poor selection as well.
- Outside the garden/orchard and at night, I use low recoil Winchester AA loads to keep noise down. I highly doubt there's a FliteControl low recoil birdshot load.
- I don't really need 3" loads, 2 3/4" has worked plenty well thus far, though I may change my mind about that later.
While porting seems cool, I don't think I'll bother with it. Recoil is fine with me, I'm very happy with the LimbSaver recoil pad. 3" magnum slugs are a breeze now.
As far as varmint size, for now it's just rabbits and small birds like robin & dove size. I've seen some porcupine roam around and with my work in the garden & orchards, that might draw them in more. I don't have a need to go after coyote or anything like that. I've not seen one close enough to shoot with a slug off a shooting bench. If they're that far out, my AR-15 build will take care of that. For close ones, I'm pleased with the Hornady Critical Defense buckshot.
I have some links for you. These are ammo reviews, even side by side of Federal and Hornady.
This is my thread;
http://www.mossbergowners.com/forum/index.php?threads/00-buck-reviewed.894/
The video links are old, they need to be reconfigured in the posts but they can be copied and pasted still.
And this one, in the first posts, the text is actually links to other threads. It's a compilation of reviews by myself and other members.
http://www.mossbergowners.com/forum/index.php?threads/ammunition-performance-reviews.2402/
I think I've seen a few of your videos before. I came across them while researching, even before I bought my shotgun. Good info you put out there.
However, I'm realizing more and more, I most likely won't use buckshot often. I only have a couple boxes just for home defense reasons and as I've said, the Hornady Critical Defense seems to serve well there. Might be nice to get some of the Federal LE low recoil rounds you talked about in your videos in case I gotta blast away indoors. Back to buckshot, I don't have big enough critters to justify patterning and testing a lot of buckshot. If I get into deer hunting, I've been collecting up some nice Federal TruBall slugs and also some 3" mag slugs. Most of the time, I'm going for birdshot, #7-#4 range.
All in all, I'm somewhat set on getting chokes threaded, it will enhance the functionality of the gun and there's no reason it couldn't increase resale value should I ever need to part with it. I should be able to get a turkey choke and hunt turkeys properly. I'm not big into hunting now but if I go down that road, it would be nice to not be limited by the gun.
With all of this said, are there any downsides to putting threads in? Weakening the barrel? Not threading it straight? Less accurate cylinder bore shots? Less accurate slugs? About the only negative I've seen is that the Mossberg warranty would be gone.