chuck--i'll give you my answers-for what they are worth
1. Won't a full choke be good enough...rather than buy a special turkey choke?
test fire your gun at a measured 40 yds on a turkey patterning target. if you can't put 5 or more shot in the kill area, either go to the turkey choke, or reduce your effective yardage. shoot 3 targets and adverage your count. my turkey choke will put (best shot at turkey shoot) 192 shot in 8x11 sheet, with over 30 in killarea(brain and spine) at a measured 40 yds. and i have witnesses!! and that wasn't with the custom card-cutter choke. guaranteed 60% of load in 30 in circle at 40 yds. i wouldn't shoot it that day because we were supposed to shoot the gun and choke we would be using. my patterns at 20 yds look like a softball hit the target!!
2. Since it's painted camoflauge on the out side ..do I still rub it down with gun oil on the outside of the barrel when I'm done hunting?
only exposed metal. the oil could interfere with paint or camo coating
3. After I shoot it should I remove the choke and reoil the threads?
not really necessary each time, but after each season, for sure. makes changing out the tubes way easier
4. Would it be ok to shoot buck shot and slugs through it?
i would not shoot buck shot thru any choke tighter than modified. it will distort your pattern, as well as damage your choke tube. they make an open choke tube that would work for buckshot.
if you have a group of guys with the same type guns and tubes, try different brands, or chokes. all shoot a little different, some a little tighter, and different size shot shoots different in the same gun. i am fortunate enough to shoot with a bunch of guys who try to find the best of everything in every gun they own. i went thru several chokes and even barrels to get mine right and wound up having custom barrel work done and custom choke made. i have a Rem. 870 wingmaster, 3 inch, with 18 1/2 in barrel, and a mossburg 500, 3 in, with 18 1/2 in barrel. both modified by same gunsmith. each gun shoots a little different. the Rem. loves # 4 shot, the Mossy loves #6. both are great shooters, and have outshot everything coming thru Jack's gunshop (we test shoot each gun he gets). could have sold them for much more than i have in them, to guys buying guns and then trying to match my patterns hanging at the gun shop, but it took me a long time to get these, and i'll hang on to them till i can't tote them or find someone to be my gunbearer
For Chuck7
When I told him Walmart had a 870 Remington turkey camo gun for 289.00 He said get it. So I obeyed.
and I got it. he is my hunting elder you know.LOL
