barre length and fps.

[profesional 111]

i see that alot a these new gunwerks rifles and other high end magnums are coming in 22 inch barrels. is it possible to maintain velocity by using a faster burning powder? or are you always going to get faster results with a longer barrel?

 

[adamg]

Always faster with a longer barrel.

And before anyone says something about going longer makes the bullet slow down, this is solid evidence to the contrary:
http://www.youtube.com/watch?v=XCqa2umL8ME

 

[Potashminer]

"faster burning powder" - for many years, was considered that whatever gets most velocity with longer barrel, also gets most velocity with shortened barrel - I think first experiments at that, that I read of - were by Phil Sharpe - circa 1940's - started with a 30" barrel in 30-06 and perhaps a dozen different loadings - cut an inch or so off the barrel and measured the velocity - and, repeat - I think he was using a ballistic pendulum to do that - I believe he ended up circa 11" barrel. Apparently that experiment repeated many times since then - what gets most velocity with long barrel, also gets most velocity with short barrel. Not sure anything "modern" has changed that.

By the way, is pretty good evidence, from similar experiments, that bullet DOES slow down in 22 Long Rifle, once barrel is longer than circa 16" to 18". Note that the experiments apparently were sawing off from the muzzle end, so same chamber, same bore throughout - except for "wear".

 

[Ganderite]

I cut a 32" barrel back to 28" in 1" steps. In 308 it lost abot35fps per inch.

 

[downwindtracker2]

That's interesting, Ganderite got 35fps with a 308. Charlie Sisk got less with 300WM. One of the myths is that powder slow powder uses the full length of the barrel, where as it's all burnt up within the first inch.

 

[bearhunter]

That's interesting, Ganderite got 35fps with a 308. Charlie Sisk got less with 300WM. One of the myths is that powder slow powder uses the full length of the barrel, where as it's all burnt up within the first inch.

It's not so much the burn as the speed the pressure curve reduces with any given powder.

When a powder is properly matched to the bullet weight and bore diameter things usually go well.

The initial "spike" of pressure only needs to be extended by a few micro seconds to have a dramatic effect on the pressure curve.

 

[MTM]

On a hunting rifle, balance a feel are more important than a few fps.

 

[track]

I have three rifles with 27" barrels, 240 wby, 257 wby and 270 win. All three shoot beyond the maximum velocity of the Nosler reloading manual with less than 1/2" MOA. It's a great advantage to have a fast flat shooting cartidge while hunting in the Great Plains........they also work great in bush country!

 

[Eagleye]

It is true that balance and feel are important. Velocity is less important.
However, I am opposed to packing around a 300 Win Mag that is delivering
30-06 velocities.
Therefore, regardless of barrel length, I prefer to exploit the potential of
the rifle/load I am using. Dave.

 

[fiddler]

There are several key players when it comes to velocity. I generally use Quick Load to calculate these for me. Much of the time slower powder goes out unburnt behind the bullet, and fast powder gives slower speeds in longer barrels.

I play with lots of variables, then confirm it with a crony.

 

[MRP]

Everyone dreams of a rifle that can blow the dust off a chalk line for a quarter mile but that will only happen on the moon. As much as the books say and things like quick load predicts until you pull the trigger over a chronograph you never really know. In a 19" 300wsm I started with 760 Winchester went through the powders I had on hand ended up with the best fps was the much slower reloader 22. Maybe some of the ones I didn't have inbetween might have been better but I'm ok with what it's doing now, at some point a extra 100fps makes no practical difference at most hunting distances.