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-   -   What effect does a longer/shorter barrel have on bullet distance? (http://www.firearmstalk.com/forums/f18/what-effect-does-longer-shorter-barrel-have-bullet-distance-23519/)

Godiva 02-17-2010 01:36 PM

What effect does a longer/shorter barrel have on bullet distance?
 
Title really says it all.

I realize that if the barrel is too short then the bullet leaves the barrel while the gas is still expanding, but how long is too long? I mean say the gas expands 20 inches (of a 24 inch barrel) down the barrel till it equals the external pressure. Why would be 24 inches be better than say 22, or 26 for example. What I'm really asking is how would you calculate optimum barrel length to maximize the bullet distance.

workinprogress 02-17-2010 03:07 PM

I'm relatively new to the research behind firearms but this is what I've learned so far. Someone please correct me if I'm wrong as I don't want to put bad information out.

This question does not get a simple answer. There are many variables that play into why a rifle shoots like it does. Which is why people spend so much money building their perfect rifle and why there isn't just one type of rifle for everyone. You have things like twist rate, barrel length and even the round you are using can affect how the rifle reacts. I do know that once you get to a certain length there is the potential for it to twist itself out of straight just from the force of the bullet. Add into this all of the other things that go into making a rifle do what it does and you have information and questions for about 1,000 different threads.

The best way to start out is to tell everyone what you want to do with the specific rifle and work from there.

CA357 02-17-2010 03:34 PM

That's a great question. Unfortunately, I only know generalities. However, you have come to the right place, we have some members here that are absolute experts.

Welcome here. Please head over to the New Member Introductions area and introduce yourself to the folks.

robocop10mm 02-17-2010 06:37 PM

It is dependent on the caliber and the powder used. Larger calibers generally use slow burning powders. In WW I many service rifles had barrels 30" or more. They still did not burn the powder off to the point equalling atmospheric pressure.

With modern powders in a cartridge like a .308, 26" barrels are not unheard of (Remington PSS). A smaller cartridge like a .223 would not likely benefit from a barrel that long. There is a point of diminishing gains or even reduced velocity, I do not know where to find that info.

I remember seeing a test using a .22 LR barrel that was made WAY long. It was fired and cut 1" shorter til it was 1-2" long. There was a point where velocity was maximized, I just don't recall what that was.

The length of the barrel is generally a compromise between velocity/accuracy and portability.

cpttango30 02-17-2010 07:11 PM

many times with shorter barrels you want a faster burning powder to get it burnt before the end of the barrel. You also need to run a slightly higher velocity to get a little more spin on the bullet. For a 22lr 18" is the optimum barrel length. Most of mine have 25" or longer barrels. After 18 you are not gaining speed and with a barrel like mine your going to lose some velocity due to drag of the barrel on the bullet. What it does is give you a quieter gun. You put my 511x next to a 10/22 and shoot the same ammo my 511x will be much more quiet.

I believe you can get good accuracy out of many cartridges with barrels as short as 20" now. Before the advent of computers that could take steel and iron ore and analyze it to tell the other computer exactly what to add and when to add it to the molten mettle it was more of a guessing game. Now we can control the quality much better in steel. So that to me accounts for being able to use shorter barrels.

If you look back many bench rest guns 50 years ago were running barrels 1" to 1.5" in diameter. This was the way to reduce barrel harmonics which can affect accuracy good or bad. Now they have found that if you use a shorter barrel of a medium heavy profile like a 1.25" to .875" taper you get a barrel that is stiffer and resists harmonics just as good as the older big giant barrels.

Look at a Palma rifle they use a 30 or 32" long barrel with the 308 win cartridge and 155gr bullets. they need them that long 1, for a larger sight radius because he larger the sight radius the more accurate the rifle. Also they are trying to get that little 155gr pill up as fast as then can make it go with out hurting the rifle or the shooter.

Just take the velocity of 3500 fps for a 223 50gr bullet in a 26" barrel with the same load in a 20" barrel your going to get roughly 2900 fps. you lose about 100 fps for each inch of barrel you lose.

Mud4Brains 02-18-2010 08:49 PM

No expert here, but I believe that most ammunition manufacturers base their ballistic numbers off of a 24" barrel. For every inch shorter you go on standard rounds (2800 fps at the muzzle of a 24" barrel), you lose about 25-30 fps of mv. Hornady lays claim that their Superformance ammo only loses about 15 fps mv per inch of barrel removed.

I haven't seen or researched anything on the other end of the spectrum which is having a barrel longer than 24" and how that affects the bullet.

I was pondering this exact topic when buying my Remington 700 VTR in .308. It's a 22" barrel with a muzzle break that further reduces the barrel size to about 20.5".

My dilemma was that I was getting a Nikon scope with the BDC reticule that's based on 2800 fps mv. If I was going to be losing anywhere from 60 to 120 fps mv, I was wondering how that was going to impact my accuracy with my particular scope. I was looking at ammo with higher mv and trying to calculate the loss to be at 2800 on a shorter barrel. It drastically reduced the number of factory loads that I had to choose from as I'm not hand-loading yet.

My problem was easily solved by getting the Cabela's edition of the VTR that has a 24" barrel with no break. Now there's an a$$load of ammo I can use that suits my needs.

indian25 05-29-2010 03:34 PM

gunsmith hint
 
Longer is the barrel of your pistol, Longer the distance's gonna be.
Cause in the barrel you got the rifling which is the spiral inside,
And because the rifling is smaller than the barrel diameter, the bullet spin.
And more the bullet spin, better it will pass through the air. We call that inertia.
So if the barrel is long, the bullet's gonna spin more.

It depend the caliber too!

Jeehs 05-29-2010 04:32 PM

Pretty much like most everyone else has said...

The longer the barrel generally the better the accuracy, Range and velocity.

But once the pressure inside the barrel reaches atmospheric pressure, The barrels going to start hurting you rather than helping you.

But for your Question, I Doubt that 24 inches would be better than 22, unless you want the gun to be quiet, Becuz drag from the barrel would slow the bullet and decrease range, accuracy and velocity. Of course that little of a change in length probbaly wouldn't really make a difference.

indian25 05-29-2010 06:18 PM

js
 
good answer dude but it was a simple answer cause of course the weather and the atmospheric condition's gonna affect the bullet distance so i should say your answer is better than mine.

Rick1967 05-29-2010 09:33 PM

I remember seing a thread where Cane had put up the results from a 44 mag that had been cut down an inch at a time. It started with a really long barrel. There was a point where the long barrel length was a hinderance on velocity. Perhaps he will post it again. I will look around and see if I can find it.


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