Does barrel length affect fps? Which length?

[2500yards]

I am going to get a barrel made for my AR. I want to see how accurate of an AR I can build for long range .223/5.56 shooting.

My question is, if I should go 24 inch or 26 inch? or should I go longer?

also is there a length at which the fps are effected by the extra twists in the barrel? or is the effect of that on a longer barrel really not a noticable issue?

Longer is better right? or is it? Im going with a 1 in 7.7 twist if this matters. planning on shooting 75-77 grain bullets.

 

[Yippeekiay]

Re: Does barrel length affect fps? Which length?

Now don't quote me on any of this but I'd go w/ the 26" barrel and probably a Minimum 7 twist if not faster. (maybe 6.somethin' or other). That way if you wanted you could mess around with 80 or even 90 grainers. It really depends on the range and shooters ability. Though I've heard many say that a 20" barrel is plenty, the CLE upper I just sold had a 26" barrel and it shot bug holes. But for pure accuracy maybe you could post the question here. http://www.6mmbr.com/index.html
As far as velocity being affected by extra twist gained from a longer barrel? I honestly don't think so. Even if it did, there're ways to offset the difference. (i.e. moly-coating). Hope this helps.

 

[gme]

Re: Does barrel length affect fps? Which length?

most highpower spacegunners are running 24"-26" lengths, the little .223 is giving you about all it can at that length anyway, if you go longer you may have to go with a longer gas tube to get it to function properly
Gary Eliseo

 

[Hummer]

Re: Does barrel length affect fps? Which length?

yes barrel length affects velocity up to a certain point and then you have friction effect of bullet rubbing on barrel and it starts to slow down.
I have barrels from 16" to 24". All have their places.
Bear in mind that velocity is not the answer to all questions. Accuracy is paramount. Think about it at 600 yards if one rifle at 2550 shoots 6 inches and another rifle launching at 2700 shoots 9 inches who is going to win assuming equal capability of shooters to hold, squeeze,align sights, read the wind mirage?
I would not go faster than 8 twist for up to 80 gr bullets. If you have to have heavier bullets go for a 6MM variant.
The bench rest boys seem to like barrels around 20".
take a look at 6br.com and there is lots of good reading. Also look for a article Secrets of the Houston Warehouse that gives some good poop.

 

[2500yards]

Re: Does barrel length affect fps? Which length?

ok. thanks for the info.

 

[Hummer]

Re: Does barrel length affect fps? Which length?

you are welcome. Hit me with a PM if you have anything I can help with. Hummer

 

[Sig685]

Re: Does barrel length affect fps? Which length?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hummer</div><div class="ubbcode-body">yes barrel length affects velocity up to a certain point and then you have friction effect of bullet rubbing on barrel and it starts to slow down.</div></div>

Yes, that point is several feet of barrel. You probably could not lift and aim the rifle.


<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I have barrels from 16" to 24". All have their places.
Bear in mind that velocity is not the answer to all questions. Accuracy is paramount. Think about it at 600 yards if one rifle at 2550 shoots 6 inches and another rifle launching at 2700 shoots 9 inches who is going to win assuming equal capability of shooters to hold, squeeze,align sights, read the wind mirage?
I would not go faster than 8 twist for up to 80 gr bullets. If you have to have heavier bullets go for a 6MM variant.</div></div>

It depends on what you are trying to do. If it's shooting at 1000 yards, the longer barrel is needed to generate the highest possible velocity. The choice should not be between a great short barrel and a ho-hum longer barrel, it should be between a great short barrel and a great longer barrel. My choice: the great longer barrel.

1:7.7 is a great twist for 80gr bullets, you do not need a 1:6.x something or a 1:7 twist to shoot the 80gr bullets. 1:8 does a great job also.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The bench rest boys seem to like barrels around 20".
take a look at 6br.com and there is lots of good reading. Also look for a article Secrets of the Houston Warehouse that gives some good poop. </div></div>

The bench rest boys may use a 20 inch barrel, but they don't use those for 1000 yard competition.