Velocity out of a 16.5 inch barrel

[gmphk]

Has anyone shot their 16.5 inch POF P308 through a chrony with 168 grain FGGM or Hornanday AMAXs?  I am trying to get help with a ballistics program without having to buy one.  Thanks for your help.

[unforgiven]

<dontknow> but welcome from Indiana brother gmphk.

[Robocop1051]

If only there was a place that kept records of Ballistics By The Inch... <lmao>

[washguy]

Hey GM  lay out the ten bucks for shooter...an app for your smart phone....its awesome :)  Wash

[Robocop1051]

..…

A Sierra 168gr BTHP .308 only requires 15.5 inches of barrel for a complete burn of the powder contained in the cartridge. The bullet gains the most speed before the initial burn is completed. After the burn, the bullet only relys on the expansion of the already burnt gas to propel it. The increase becomes quite minimal very fast afterwards.

....

The first five inches are the most important, as the bullet quickly jumps to about 1550 fps. From that point the bullet gains another 140 fps per inch till it reaches about 2200 fps at about the 10 inch mark . At 15.5" (or 16")you should be shooting around 2500 fps , meaning an average of 100 fps per inch from the 12" mark. After that point you will generally only gain about 40-30 fps per inch tapering off gradually as the barrel gets longer. At 20" you should be flying at approx 2600 fps. With a high estimated 2700 fps at 24"

So to answer your original question, about 2550 fps (give or take 25fps)

[gmphk]

So to answer your original question, about 2550 fps (give or take 25fps)

Thank you for the information.