Barrel length quwstion?

[Wookie316]

I know longer barrels add to your FPS.

My question is 2 parts.

1. How many FPS per inch do you loose on average?

2. How does barrel length affect max load pressure? Does a longer barrel with the same load have higher pressure or is it affected?

 

[Plowboy]

the best rule of thumb I know on barrel length is 20-25fps per inch

I'm pretty sure that barrel length does not affect max chamber pressures

 

[Ernie]

Some it depends on the cartridge you are shooting as well.
I have seen as much as 40 fps per inch.

 

[Leathel]

What Cal?? smaller cal less diference the longer it is......Over bore cals need longer and will gain more per inch

Saw an article on 6mmBR that tested between 28-33 inch and past 28" the average was around 8fps.....but they didn't test shorter unfortunatly

 

[Wookie316]

Dad's 7mm is 24 1/2" long & my 264 Win Mag is just over 26". You wouldn't think the extra 1 1/2 would be much of an issue in the field, but I find it somewhat clumsy & awkward compared to Dad's 7mm, especially going through light bush.

1 1/2" shorter on a 264 Win Mag shouldn't make much difference?

 

[Long Time Long Ranger]

Depends on several factors. Big overbore small caliber magnums can gain quite a bit with barrel length. Short efficient cartridges like the 6mm BR gain very little. For example my 257 and 264 STW's have gained as much as a 100 fps going from 26" to 28" of barrel length. My big 338's including the Lapua, 338-378 wby, 338 ulttramag and 338-300 ultramag average about 20 fps per inch. Powders and primers also affect barrel length velocity. Sometimes with a faster powder and hot primer to get all the burn quick as possible you can overcome some of the velocity loss in a shorter barrel. Lots of factors and there is no set velocity gain per inch of barrel. It will differ with each cartridge or class of cartridges.