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# Barrel Length and Bullet Velocity Ratio

#1
05-07-2013, 11:11 AM
 Gold Member Join Date: Nov 2012 Location: Green River, Wyoming Posts: 539
Barrel Length and Bullet Velocity Ratio

Alright I need some experienced input...

The way I've seen it/been taught to see it is that 1" of added barrel length will result in about 50 fps added velocity... But I've recently read a few articles that seem to suggest otherwise.

For example: The way I was told, a given bullet which will reach 3000 fps from a 28" barrel will probably be capable of about 3050 fps from a 29" barrel given that the other elements are roughly the same (powder charge, primer, twist rate, bullet weight, etc...)

Is this a correct method of thinking or is it not even close to correct?? How much does it differ with different cartridges? If you could please give some examples from your own experience it would be much appreciated...

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-Clint

#2
05-07-2013, 02:44 PM
 Platinum Member Join Date: Feb 2009 Location: Sedalia, MO Posts: 1,256
Re: Barrel Length and Bullet Velocity Ratio

CB11WYO,

There's very little in this game that's linear, and this is yet another example of that. Velocity gain/loss in re barrel length varies substantially with the barrel lengths we're talking about, the expansion ratio (cartridge capacity), the bullet weight and many other factors which come into play. Bottom line is, it's all over the place, and virtually impossible to say that X increase or decrease in barrel length results in Y velocity change.

Sorry, and I wish there was a simple answer to this one, but the question is a little too broad for a single, concrete answer.
__________________
Kevin Thomas
Lapua USA
#3
05-07-2013, 03:41 PM
 Silver Member Join Date: Jan 2013 Location: Kansas Posts: 201
Re: Barrel Length and Bullet Velocity Ratio

Yea I agree, everything in shooting is relative. Logically it can and does increase velocity, but exactly how much depends on your rifle.
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#4
05-08-2013, 01:36 AM
 Silver Member Join Date: Jan 2009 Location: Sweet Home OR Posts: 192
Re: Barrel Length and Bullet Velocity Ratio

I agree. There is no positive way to calculate what velocity you will get. Example i have a savage 308 with a 26" barrel. It shoots a 155gr amax at 2955 average on the last 5 shot string through my chrono. My buddy has a savage 308 with a 24" barrel. Same exact load same chrono on the same day. His 5 shot average was 2951. But I have a 168gr amax load that shoots 2870 out of my 308. The same load in my buddies rifle only shoots 2830. Hope my experience helps you out.
#5
05-08-2013, 09:29 AM
 Gold Member Join Date: Nov 2012 Location: Green River, Wyoming Posts: 539
Re: Barrel Length and Bullet Velocity Ratio

Quote:
 Originally Posted by Kevin Thomas CB11WYO, There's very little in this game that's linear, and this is yet another example of that...
That's what I was afraid of... oh well

Thanks!
__________________
-Clint

#6
05-08-2013, 09:31 AM
 Gold Member Join Date: Nov 2012 Location: Green River, Wyoming Posts: 539
Re: Barrel Length and Bullet Velocity Ratio

Quote:
 Originally Posted by luke I agree. There is no positive way to calculate what velocity you will get. Example i have a savage 308 with a 26" barrel. It shoots a 155gr amax at 2955 average on the last 5 shot string through my chrono. My buddy has a savage 308 with a 24" barrel. Same exact load same chrono on the same day. His 5 shot average was 2951. But I have a 168gr amax load that shoots 2870 out of my 308. The same load in my buddies rifle only shoots 2830. Hope my experience helps you out.
Yup! Thanks that's a good example.
__________________
-Clint

#7
05-08-2013, 09:32 AM
 Gold Member Join Date: Nov 2012 Location: Green River, Wyoming Posts: 539
Re: Barrel Length and Bullet Velocity Ratio

Just too many variables to work with, too many gun "personalities" in the mix I guess.
__________________
-Clint

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