New to the forum and new to the M&P sport and was wondering if it was worth buying a bull barrel for my rifle I am mostly going to shoot prarie dogs with it just need some opinions

The main advantage of a bull barrel is that it takes longer to heat up.

The additional weight will attenuate recoil. Even though a .223 really doesn't recoil that much, it will add up over time if you are in a target rich environment.

One problem with a bull barrel is that it screws up the rifle's balance. You may want to add weight to the butt stock to balance the rifle to your liking. However, more weight=less recoil.

What you will want is a free floating barrel. That is the one most important thing you can do to an AR to make it more accurate. At that point if you choose to add a heavier free floating barrel, it will be cheaper to simply buy another upper.

Bull barrels have less flex.

Heavier gun in general helps reduce unwanted shooter influence.

I've seen guys mortgage their homes trying to get an AR platform to shoot as well as a $500 bolt action.

A DPMS, Windham or other Varmint upper might be worth considering.

what about accuracy I haven't had a chance to shoot my sport yet so I really don't know how accurate it is with stock barrel

A good trigger upgrade and quality optic will increase the accuracy of your rifle. If you are looking to shoot sub minuet of angle groups at 500 yards, the AR platform is probably not your best choice.

Yea, I know, there are some very accurate AR's out there, but not at the M&P Sport's price point.

You haven't shot your rifle and you are already contemplating replacing the barrel? May I suggest that you go shoot it and see if it works for you first?

Some users have been able to pull sub-MOA groups from Sports with handloads, trigger upgrades, and free floating barrels... Some users shoot close to MOA with a stock Sport and match grade ammo... And some shoot 4 MOA with the cheapest ammo off the shelf and are still quite happy!

Shoot the thing first, a lot. Use different ammo. Accuracy will very with different ammo. You're not going to hit prarie dogs at 100 yards with cheap ammo, at least not with any consistency. Accurate bullets are expansive which will mean expansive prarie dogs. Add to that the price of converting your AR and the scope and you're better off just buying a bolt action rifle and a scope

It also matters what range you expect to shoot praire dogs at. I'm with Phil, hitting itty-bitty critters at long range isn't why one buys an AR.

A bull barrel cuts down on the barrel harmonics.

I've built a few ARs. I built one as a "varmint" rifle with a 22" SS Wilson bull barrel. 1/8 twist. Another was built as a 3- gun rifle with a Latitude Armory 18" standard profile barrel. 1/7 twist. Both were chambered in 223 Wilde. The 3-gun rifle shot and continues to shoot better groups. I traded the varmint gun. I have a .556 14 1/2" 1/8 pencil barrel that shoots almost as well. Lessons learned.