I'm looking into getting a rem choke barrel for my gun. Currently it has a full choke barrel no screw in choke option. 40 yards my pattern with tss #7s is ok at best. Make me feel good about a 21 inch barrel purchase lol. I know opinions vary what the general consensus on choke choices for this barrel using tss shells.
Just my 2 cents.
I have the first year model for the Rem. 870 "Special Purpose" which was a fixed full choke, bought before the spring of '86. My thoughts at the time were to pay Mark Bansner a visit and have the barrel cut down and re-sleeved with his tight turkey choke. After patterning a bunch of different shells, I decided against it. With the right loads, I knew I could easily kill any turkey at 40+ yards, yet it was open enough that I wouldn't miss birds in close (under 25 yards).
I'm still using that gun today. I found that it likes big payloads (2 oz.) of Heavyshot Blend even better than lead, as I believe most guns do.
You didn't state what is meant by "your patterns are OK at best". I never got into chasing that "the more in a 10 inch circle at 40 yards,
the better" number. Obviously, you want a good, even pattern that is denser in the middle, but I think you should also take into account how tight your pattern is at close range because it may cause you to miss those head juking birds.
Just another way of looking at it that certainly doesn't get mentioned much these days. I will say, it has saved me a ton of money (and frustration) over the years. Just point, shoot and KILL. And kill it has.
Good luck.