Barrel length vs. velocity

[Pat B.]

Wondering what the ideal barrel length is for a 6.5x47 Lapua.

Main goal is velocity without the finished rifle being to cumbersome.
I've had rifles with 30'' barrels and am ok with that. But I wonder how much you're gaining
over a 26''er..

Is there a point (reasonable) of diminishing returns ?

 

[chipsfan]

I just began working on loads for a 22"- I got 2831 fps with a 120 Scenar L shooting .199-.225" at 100yards.

the 140 SMK loads I tried were real slow, 2470 was the fastest- it was uber accurate.

I still have some load development to do. Powder was Varget- CCI benchrest primers

 

[valkyries]

I think a gain of around 25fps is a reasonable guesstimate. But then it may also depend on the burn rate of the powder your using as well. So you may gain around 100fps over a 26" barrel. Whether its worth the extra length and weight is your call.

 

[Matt P]

I have just put together a 6.5x47 Tac rifle, I used a barrel off one of my F Class rifles, when it was 30" long 130 VLD's made 2900 FPS, I cut it down to 23" now with the same load does 2820 FPS.
Hope that helps.
Matt

 

[M40_A1]

When cutting down a barrel, the finer the teeth on the hack saw, the smaller the burs at the crown and the less muzzle velocity drop you will experience. Always remember to debur with a power drill.

-Bubba

 

[Nik H]

Wondering what the ideal barrel length is for a 6.5x47 Lapua.

Main goal is velocity without the finished rifle being to cumbersome.
I've had rifles with 30'' barrels and am ok with that. But I wonder how much you're gaining
over a 26''er..

Is there a point (reasonable) of diminishing returns ?

Hi Pat,

The rule of thumb is 20-25 fps per inch of barrel. It has served me well over 20 years of reloading. Best way is to chronograph the various loads if you have the equipment.

BR,

 

[Pat B.]

I do have 3 different chronographs but I hate to experiment by cutting a new barrel shorter than is ideal for max velocity.. Once its cut ------.

Actually I employ a hacksaw on barrels quite often but I hate using a fine tooth blade, takes too long to cut through a barrel. And I've yet to see it influence velocity.. What's crown have to do with a barrel, I thought crown was something you drank after a long day of sawing ??