18" or 20" barrel for .308?

[Pappabear]

I'm looking at a. 308 precision bolt gun build, and I would like to see how much capability I lose going from 20" to 18". I'd like to keep it short, but not if it hurts its ability to perform well at long ranges. The idea is to put a can on it and possibly a folding stock for transportation.

As you have been told, your not going to lose much, but I wouldn't spend money to cut 2 inches off a 20 inch barrel. Just my thoughts. If your buying a custom, thats another story.

[orkan]

Yeah, if you are cutting down from 20... go to 16!

[TehLlama]

which is the only thing that matters.

But this is the internet - the prettiest three round group at 100yds always wins.

[1911-A1]

As you have been told, your not going to lose much, but I wouldn't spend money to cut 2 inches off a 20 inch barrel. Just my thoughts. If your buying a custom, thats another story.

I'm looking at a build from Sniper Central. Probably their Remington 700 package.

I was mostly looking for deal breaking reasons to not go with an 18" barrel. I don't expect to shoot at a mile with this gun, probably 500yds max at most of the ranges around here. Likely 100-300yds on average.

[The Surgeon]

For every inch you cut off, you are going to loose about 20- 30 fps was the old theory. But. with components getting better, powder, barrels, etc. I think this philosophy is changing. To many variables to account for to give you a definite answer. You may loose velocity, then again you may gain, and then there is the possibility that you do not see a change.

Powder burn rate, land/groove diameters, twist rate, bullet weight, primers (hot or cool), on and on and on.......... fast barrel, slow barrel, ect...........tight chamber, loose chamber, long throat, short throat......on and on and on
Quote from: sBruce;http://www.longrangehunting.com/foru...n-loss-68730/; Sept,21,2012

I seen that 500 yrds is about all this rifle is going to shoot out to because of your surroundings where you live?

What happens if that changes and you do have the opportunity to go beyond that 500 yrd mark on a regular basis in the future?

I have seen some guns that have had the barrels cut down that have had more velocity than that of the same gun in a longer barrel, and vise versa. It all depends on the components.

[orkan]

I have seen some guns that have had the barrels cut down that have had more velocity than that of the same gun in a longer barrel, and vise versa. It all depends on the components.

Kind of goes without saying doesn't it? If you change components, then obviously you'll change the outcome. Lighter bullet, faster powder = more velocity. That being said, take the same lighter bullet and faster powder in a long barrel and it will still be faster than the short barrel. Name an instance where this does not happen. List the components that would make that not so.

With equal components, a short barrel will NOT be faster than a long barrel, unless you are talking about a 50" barrel and cutting it down to 30 or something insane like that, where the added barrel length actually creates more friction than the pressure is able to overcome.

Otherwise, all things being equal, shorter is slower... longer is faster. Just the way it is.

[The Surgeon]

Kind of goes without saying doesn't it? If you change components, then obviously you'll change the outcome. Lighter bullet, faster powder = more velocity. That being said, take the same lighter bullet and faster powder in a long barrel and it will still be faster than the short barrel. Name an instance where this does not happen. List the components that would make that not so.

With equal components, a short barrel will NOT be faster than a long barrel, unless you are talking about a 50" barrel and cutting it down to 30 or something insane like that, where the added barrel length actually creates more friction than the pressure is able to overcome.

Otherwise, all things being equal, shorter is slower... longer is faster. Just the way it is.

I was watching a documentary on discovery. I thought this as well i.e. longer faster; shorter slower. Till I seen this documentary. Two AR's one with a shorter barrel and the other with the longer. The shorter barrel was a bit faster. I can't remember the name of the program. Although it was a program, to many unknown variables that most likely were not talked about i.e. charge, bullet weight.

Just wish I could remember the name of the program. I can remember the contents of the program well. My dad and I argued about it the whole day. LOL I was like you, longer equals faster. My father was the other way. When they showed the results, I heard about it all day. LOL. But no kidding, the shorter barrel did post the high velocity. I don't understand it, it goes against everything we are told about velocity and barrels. But it did.

I will try and find the program and let you know what it was. Maybe, if I can find it, you can see something that I was missing. But like I said, it did post the higher velocity and it should not have.

[The Surgeon]

I sent some e-mails out to see if I can't track this down for you.

See if I can get the components and set that was used in the test. Cross the fingers and wait.


I am like you, this should not be the case. Like I said, it happened though. I didn't here the end of it all day from the ol' man. LOL

[orkan]

this should not be the case. Like I said, it happened though.

Lots of things happen on TV... doesn't mean its true.

The only way that could possibly happen with the same load/cartridge/components, is if one rifle had a tight bore, increasing pressure. ... or had moly bullets, or moly barrel, etc.

In other words, some other variable was changed IN ADDITION to barrel length.

[BrigandTwoFour]

Does that 10-20 FPS per inch rule apply to gas guns as well?

I've been trying to figure out if I want to go 18" or 20" on a .308 AR build.