Velocity change / barrel length

[Teac]

Guys,

I was doing some ballistics calculations and the online velocity data is often not given for my barrel length (.223/26") . Federal does not seem to even give the barrel length (couldnt find it) for which its velocity was measured.

http://www.federalpremium.com/products/details/rifle.aspx?id=146


I also used some S&B match ammo and they give velocity for a 23.5" barrel.

There is lots of discussion from the AR15 guys how 1" less barrel will drop velocity by a certain amount. Can I use the same "formula" and add the same amount for my longer barrel or will this be off?

Thanks

Matt

 

[shredder0]

Guys,

I was doing some ballistics calculations and the online velocity data is often not given for my barrel length (.223/26") . Federal does not seem to even give the barrel length (couldnt find it) for which its velocity was measured.

http://www.federalpremium.com/products/details/rifle.aspx?id=146



It is all about your particular rifle. It may or may not conform to any "rule" about velocity per inch of barrel.

I read an article by noted ballistician Phil Sharpe that detailed cutting down a 30-06 barrel an inch at a time from 30 down to 12. He shot many different loads at each length with a variety of powders. End result: there is no rule. Velocities in some cases INCREASED as the barrel shortened at certains lengths, though of course the overall trend was downward. There was no rhyme or reason to the velocities , nor could any formulae predict what the various burning rates of powders combined with various bullet weights would lose per inch of barrel. It was a real eye opener all done with one rifle in the name of shooting science, rather than compare different rifles with different barrel lengths because they happen to shoot the same cartridge.
All inches are not equal in potential velocity either. Gaining or losing an inch at 12 inches of barrel is entirely different than gaining or losing an inch out at 28 inches.

You could use an average but remember this- A man with one foot in a bucket of ice and another in a fire, is on average comfortable.