# Barrell length vs. velocity?



## Wolf6151 (Jun 13, 2005)

How much velocity is lost or gained for every inch of barrell length? If shooting the same cartridge/caliber (.308) in a 24in. barrell vs. 26in. barrell, all other conditions being equal, how much velocity would be lost or gained? Thanks.


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## Bill Fisher (Apr 12, 2006)

*my best guess........*

none.......


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## Texas T (May 21, 2004)

There isn't any clear-cut answer as to how much velocity will be lost per inch of barrel length reduction. The amount of loss is closely tied to the expansion ratio. The type and amount of powder, as well as the weight and bearing length of the bullet, also play a major part. Rifles with high expansion ratios (smaller calibers) tend to lose less velocity than rifles with low expansion ratios (larger calibers).


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## prarie dog (Feb 28, 2011)

Ditto and Ditto, had two 308's back in the day one with a 20" tube and the other with a 24" tube. The common high speed accuracy load for these rifles was (give or take a tick) 42GN of 4895 and the 168SMK. The 24" tube was about 20fps slower than the 20". Having said that, if I was developing loads for max velocity I think the 24" would have won out using a slower powder like 4350.


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## muddyfuzzy (Jan 2, 2011)

Bill Fisher said:


> none.......


me thinks not.


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## Wolf6151 (Jun 13, 2005)

I've always been under the impression that the longer barrell gives a longer burn time for powder thus a higher velocity. I've always been told that you lose approx. 50 ft./sec. for every inch of barrell length.


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## Texas T (May 21, 2004)

Very slow burning powder could use a longer barrel and very fast could get by with shorter but again there are so many variables that come into the equation, as I said earlier. The 50 fps might apply to one caliber and one bullet with one powder but wouldn't hold true for another.


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## muddyfuzzy (Jan 2, 2011)

if barrel length does not change anything why do ALL reloading texts specifically mention barrel length at the header page on every cartridge opening data?


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## Bill Fisher (Apr 12, 2006)

muddyfuzzy said:


> me thinks not.


think not but don't have an answer?....... (pfffft! )

'none', as in 'none that matters'.....any difference would be an insignificant difference between 24 and 26" barrels for a .308 caliber

someone would really have to be jacking with powders and loads to create a significant difference in a 308's velocity between those two barrel lengths


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## hillbilly deluxe (Jun 7, 2007)

medium case capacity rounds such as the 243 Win to 308 win will gain about 15-18 fps per inch over 22" then start dropping after around 28". It all has to do with case capacity to bore volume ratio. But if your not shooting long distance then don't worry about it just get one that fit your kind of hunting the best. For me that's around 32-34" long barrels on most of my big rifles but 99% of my shooting/hunting is long distance stuff over a 1000 yards. but i would be happy to give up some seed to get a better shooting rifle or one that fit the picture better. If you hunt out of a blind or truck then a short barrel is better good luck.


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## Bill Fisher (Apr 12, 2006)

hillbilly deluxe said:


> It all has to do with case capacity to bore volume ratio.


bingo.........

several years back when Browning came out with their 10ga BPS in a short 22" barrel i was interested in one cuz i shoot geese from pit blinds so i called to ask if their was any significant loss in velocity (cuz steel shot uses slower burning powder as opposed to lead)......... and all the head of mfg could say was, "ya know..... that's a good question"

i laughed cuz they didn't even think about it before making a barrel that short

i bet that thing would look like a flame thrower with all the powder burning in the atmosphere instead of in the barrel......... :biggrin:


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## Wolf6151 (Jun 13, 2005)

The reason I ask this question is to compare the Remington SPS Tactical 20" barrel, Remington 700 5R Milspec 24" barrel, and the Remington 700P 26" barrel all in .308 caliber.

I really wish they made these rifles in 7mm-08, I prefer it to .308.


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## Texas T (May 21, 2004)

Buy all three and then you can see if there is a difference. LOL :biggrin:


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## CoastalOutfitters (Aug 20, 2004)

Wolf6151 said:


> I've always been under the impression that the longer barrell gives a longer burn time for powder thus a higher velocity. I've always been told that you lose approx. 50 ft./sec. for every inch of barrell length.


prob about right, to a point max burnthru or increased friction in a super long barrel and bad chamber pressures

case in point 44 mag load data for the revolver vs 44 mag carbine is different because of barrel length and chamber pressures

you want max powder burn thru before the bullet exits the barrel, so for optimal load , you have to tinker with the various powder's burn rate to get the best charge combo for that weapon's barrel length


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## CHARLIE (Jun 2, 2004)

I want the shortest and lightes gun I can find. The criter is gonna wake up dead and have no clue if a 22 inch or 26 in barrel killed him. Too much worry here for such a small difference.


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## Wolf6151 (Jun 13, 2005)

CHARLIE said:


> I want the shortest and lightes gun I can find. The criter is *gonna wake up dead* and have no clue if a 22 inch or 26 in barrel killed him. Too much worry here for such a small difference.


I'll be using the rifle for target use, maybe the occasional deer hunt, but 99% of the time I'll only be killing paper. Are you shooting zombies? :biggrin: If so I want in on this, sounds like fun. What's the daily bag limit?


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## CHARLIE (Jun 2, 2004)

Wolf6151

Nope not zombies just normally deer or a few hogs with my guns. If your shooting paper most of the time I dont understand the concern regarding velocity. What you want is accuracy I would think so probably a bull barrel, good trigger and some type of bedded stock. Oh yes a good scope. Accuracy is certainly important in my hunting guns so I have put lots of time in getting them to shoot to my satisfaction. The only thing I dont have in the above list are bull barrels on my hunting guns. Good luck and I bet that paper wouldnt care if it was shot with a 24 inch barrel or a 26.


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## hillbilly deluxe (Jun 7, 2007)

Wolf6151 said:


> I'll be using the rifle for target use, maybe the occasional deer hunt, but 99% of the time I'll only be killing paper. Are you shooting zombies? :biggrin: If so I want in on this, sounds like fun. What's the daily bag limit?


 Then in that case you may want to take a real hard look at savage. the new savages have a lot to offer and shoot really well. They also have 7mm-08 if that's what you really want. but for target shooting i would be looking at a 6.5x284 or 6mm NORMA BR. I have a friend that started shooting with me that had to have a 308 so he got the savage Model: 10 FCP HS Precision he is shooting it out to 750 yards with great results with reloads and not bad with factory loads.
What kind of target shooting are you talking about? Do you reload are do you plan on doing so?
check out savage they shoot!!!!!!!!!!!
http://www.savagearms.com/


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## hillbilly deluxe (Jun 7, 2007)

Wolf6151 said:


> I've always been under the impression that the longer barrell gives a longer burn time for powder thus a higher velocity. I've always been told that you lose approx. 50 ft./sec. for every inch of barrell length.


 This is true longer barrel longer burn time the more speed you gain up to length of barrel that the powder has mostly burned up there for not making enough pressure to add much speed. If you add a 30+" barrel to a 223 you will see a gain of 15-18fps up to around 26" after that your gains per inch will start dropping off fast not worth the length are weight. This is cause you're running out of burnable powder.

The idea that you will get 50 fps for each inch added is kind of a myth in the shooting world. If you average all the rounds out there. I would say you're looking at around 18 fps per inch added over 24" up to the point 
your case capacity to bore volume ratio has equaled out. then it just drops off.

The best thing to do is find a rifle that shoots good and not worry about all this kind of stuff. Like i said earlier i'd be happy to give up 100-200FPS for a better shooting rifle any day. 
Good luck


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## THE JAMMER (Aug 1, 2005)

I have never done any empirical testing of this, but I, like others, have always heard the 25-50 fps per inch of bbl. I would venture to guess that for a fixed gun, bullet, load, etc. that the longer bbl would give higher velocity. The military sniper guys seem to be moving to shorter bbls, but they have also said that they "are willing to accept the slight loss of velocity (juice they call it) for the increased mobility. So they seem to be saying that the shorter bbl gives less velocity and they should know. I guess that their assessment is that the loss is not significant enough. Of course that only applies to the calibers that they shoot.

THE JAMMER


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## Wolf6151 (Jun 13, 2005)

With this newfound information that the increase in velocity isn't what I thought it would be I'm now leaning more toward the Remington 700 5R in .308. This rifle will be a paper puncher 99% of the time shooting mostly from 100-300 yds. with the occasional shoot at 600-1000 yds. and possibly used on a future deer hunt. I was considering the 700P due to the longer barrel and greater velocity for the 600-1000 yds. shoots but since the increase in velocity isn't what I thought it would be I'm now leaning toward the 700 5R.


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## CHARLIE (Jun 2, 2004)

Wolf6151

Now your talking, no need to make mountains out of mole hills as my dear ole Mom used to say


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## THE JAMMER (Aug 1, 2005)

Like Troy on Swamp People always says. "CHOOT EM, CHOOT EM."


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## CHARLIE (Jun 2, 2004)

Dont you just love ole Troy ? Man dat's a tree breaker dar...


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## THE JAMMER (Aug 1, 2005)

CHARLIE said:


> Dont you just love ole Troy ? Man dat's a tree breaker dar...


He's the best. I've heard that he has become such an icon in Louisiana, that when he walks into LSU stadium, the whole crowd jumps up and cheers for him. How cool is that.


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## CHARLIE (Jun 2, 2004)

jammer

Not to steal a thread but I have to tell you about missing something that looked like maybe a rabid coyote or maybe a chuacabra


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## Wolf6151 (Jun 13, 2005)

I'll be headed to the gun show this weekend at the GRB looking for a good deal on a 700 5R, then I'll turn my attention to picking out a scope for it but I've already narrowed the field and have a few in mind. Thanks.

Anyone else headed to the gun show this weekend?


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## THE JAMMER (Aug 1, 2005)

I'll be there Sunday.


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