I am in the process of ordering a new .223 barrel for my black rifle and I have the option of a 14.5 inch barrel with a pinned flash hider to make it legal here in the good old US of A, or a 16 inch barrel, both with 1-7 inch twists from a barrel maker that makes very accurate barrels. The intended use is medium range shooting 200-300 yards with 77 grain bullets. My question is regards the velocity. Is there a significant velocity loss from 16 inch to 14.5 inch with the .223? I probably will mount a trijicon TA31 4X on the rifle so it is what I would refer to as a medium range gun. Thoughts?

You'll lose 50 to 100 fps with the shorter barrel.
Personally, I would use a 16" with a screw on flash supressor probably a Vortex .

The rifle will still be plenty compact, option devices can be attached to the barrel and you have one less thing to effect accuracy (the pinned,welded, staked whatever permanently attached flash supressor).

A 16" barrel also allows you to go with a mid length gas system which is a real plus as far as reliability and function.

If you really want a short barrelled rifle, pay the tax and get a real SBR.

good luck
Covey16

Go with the 16" barrel. Especially with the 77gr bullets.

The 16" barrel makes it easier to change the configuration later.

The above poster is right on about the mid length gas system. The mid length gas system is a good choice, but don't overlook a carbine system if you find a good deal.

I have a 16" carbine that I made shoot much better and softer with the addition of a 9mm buffer, Youngs NM carrier and a LMT bolt. Very accurate and reliable set-up.

ZM

http://www.ammo-oracle.com/body.htm

Due to the poor performance of M855 ammunition, particularly in short-barreled carbines of 10.5-14.5" in length, Navy SEALs, and eventually other SOCOM units, began experimenting with using loads originally designed for marksmanship units for combat.

The Marines (in conjunction with a large Federal LE agency) did extensive testing of this large experimental batch of BH loaded Nosler 77 gr cannelured OTM's in the Fall of 2002. It offered outstanding terminal performance out to the maximum test distance of 300 yards. They then ordered 1.1 million rounds of cannelured 77 gr OTM's via the existing Mk262 SOCOM contract (which did not specify a manufacturer) administered through Crane. The cannelured 77 gr load was designated Mk262 Mod 1, and the orginal Mk262 was re-designated Mk262 Mod 0.

So, conclusion. IF you limit your shots to 300 yards, 14.5 inch barrel should do.
My issue with it was the pinned flash suppressor. I wanted to be able to change the flash suppressor.

Yeah, you wouldn't want a prairie dog or woodchuck to see the muzzle flash and make your position. Better ignore muzzle blast and velocity loss and go with the shorter barrel in order to have the ESSENTIAL flash suppressor. Also, be sure to wear body armor when hunting any animals over 2 pounds.

Stonecreek's reply was the capper, I was thinking it would be a bit lighter with the 14.5 but the 16 will provide more velocity, hang the Pdogs seeing the flash anyway it cannot have anymore flash that my 23 inch 300WSM with a max charge of RL19 at first legal shooting light....