i have the option of using a 26" or 30" barrell on my 870. does the longer, heavier barrell give me any noticable velocity advantages?

Not much if any, the shorter barrel will be the best choice if you want it for mainly turkey hunting.

I think i read somewhere that after 26" you don`t get much more velocity. It does make a difference if your barrel is real short 21" versus 26" etc.

FYI...the idea that longer barrels equates more range/speed/power comes from the days when it really did make a difference. The powder used today is different from the powder your grandfather shot. Back then the powder didn' t burn as fast as it does today, so they needed the longer barrels to contain the explosion for a longer period of time. It was especially important to the waterfowlers back then.
Like Strut & Turk-man said not much. The biggest effect barrel length will have on your gun its balance & handling. Maybe something to consider if you plan on using the gun for wingshooting in addition to turkeys. Then there' s the weight issue. If you don' t need the extra weight, don' t get it. Bottomline...26" will do fine.

I use a Rem 870 exp mag 12ga pump w/20" barrel w/extra full turkey choke. Using 3" magnum shells.

The shorter barrels are much easier to manuver around brush when set-up, also when your gun is slung over your shoulder it won' t catch the branches or brush as your walking through the woods as a longer barreled gun would!! Like mentioned above, modern shotshells burn up their powder completely within the first 18-20" of barrel length!! So by shooting a much longer barrel your really not gaining anything. A long barrel is better suited for duck or geese shooting where wing shooting mandates a longer sight plain and balance for that kind of shooting. I prefer a barrel length of 21-24" tops!!

I' d go with the 26" barrel

The longer the barrel the more velocity you will have. I would go with 30" barrel.
wernerjd

If I am not mistaken most major shotgun ammo manufacturers test and report their velocity figures after firing from a 30" barrel. If they in fact do this and you are shooting a shorter barrel you will not achieve their published velocity. Read this link from Nitro ammo : http://www.nitrocompany.com/pattern.htm


I' m not going to repost their actual numbers because you can go to the link I provided and read for yourself. I personally use a 28" barrel and it works well for me. It can be a little more cumbersome to move around but I do not mind it.

26 inch is a good length. Right in the middle. You have a longer sighting plane than a 20 inch barrel. 30 inch is a bit long.