I just tested the same load in a 20" Savage and a 16" FNAR. It was Speer 150 Mag Tip over 47grains of R15. Velocity from the Savage averaged 2875 fps and the FNAR was 2685 which would suggest 45 fps per inch velocity loss. Not apples to apples because some barrels are faster than others which is the variable but it's in line with what I thought it would be. I've read velocity loss is less with heavier bullets as you shorten a barrel as well.

FN, as in gas gun versus 20" bolt gun?

Yes.

Can't leave out the gas gun tax. Comparing a 20" bolt gun to a 16" gas gun is comparing two variables at the same time. Comparing barrel length as well as bolt action vs. gas gun simulateously.

Morgan cut four inches off my .308 model 70. When I get it back together I'll chronograph the same load and report the difference.

Got it. There is also variation in barrels. You can have some fairly wide variances in 20" Ruger, 20" Savage & 20" Remington using the same caliber and load. Some barrels are faster than others.

I've always heard the optimum barrel length for a 308 is 20". You don't lose as much from 24" to 20" as you do from going 20" to 16". Once again, not an expert and I know it's complex. I just happened to have my Magnetospeed at the range a few weeks ago and wanted to compare the velocity of the same load in two different rifles. It was fresh in my mind so I just mentioned it.

Without a doubt some barrels are faster than others. Optimum barrel length depends on what you want to do. Any length barrel can be made to shoot with load tuning. The long ones, if thin, cam heat and string in less shots. If you want the speed of a long barrel, as well as the long shot string shootability, then you have to make that barrel heavy.

I just got my 6.5 Creedmoor back from having Jon Beanland chop it from 25" to 22" and thread it for a suppressor. I lost right about 55-60 fps for the 3" chop, or about 20 fps per inch. I had asked him how much I would lose, and he estimated 60-90 (not per inch, for the whole 3" chop). Glad mine was on the low end and not top end.

I just bought a light weight 243 for my new coyote rifle, got tired of carrying heavy rifles out walking. It got mailed to Morgan yesterday to chop and thread it. I told him to chop it to 21", but am concerned that might be a bit much on a 243. My main goal is I want light and handy with an Omega on it, but I also don't want to loose too much if I want to reach with it.

The heavier bullets give the powder a bit more time to burn within the barrel, doing its job instead of just pooting out the end to burn in the atmosphere instead.

This may be part of why larger calibers work out better than smaller calibers (same case volume, as in .243 compared to 358 Win) in shorter barrels.

Another factor is that the larger caliber barrel has more internal space for the powder to burn in, so it burns more quickly and thoroughly within a given barrel length.

So, if you've just gotta have a really short barrel, you'd be doing yourself a favor by going to a larger caliber. This is one reason why I will be going with .308 on my projected 18" HB rifle instead of one of the 6.5's. - Then there's the fact that heavy-barrel .308's are everywhere, but heavy barrel 6.5's are not as common. Ideally, I'd be going for 338 Federal, or maybe .358 Win.

Another project here, a bolt-action carbine in .450 Marlin will only have 20" of barrel on it.

I guess all the deer and hogs and coyotes I've killed with 18.5 inch Remington 742 and 750 Carbines are not as dead as the ones I killed with the 26inch Savage 10 FP.

Making a rifle effective is a personal choice. I have three rifles I hunt with, the remington 750 for 200 and in (although it is safe and sporting at 300), the Savage 10FCP-K 20 inch for 100-400, and the Savage 10FP 26inch for long range shots on paper, or varmints, or bass.

They are all effective for what I choose to carry and hunt with in a certain environment.

Clint said it best, "A man's got to know his limitations"

There is a famous case of an elephant in 'must' located in India being killed with a .22lr single-shot. - Eventually.

Just about anything that launches a projectile can kill. Some years ago, a five year old child was accidentally killed by his older brother with a pellet rifle. The pellet penetrated his cheat and stopped his heart.

So, just the fact that animals are efficiently killed with a short rifle does not prove much, as far as relative power and velocity are concerned.

And yes, your longer-barreled rifles, firing the same ammo, will cause the bullet to penetrate more deeply, open up quicker, etc. and so be more effective in more situations than it would in a shorter barreled rifle. With some cartridges it makes more difference than with others, but it always makes a difference.

This is simple physics 101 stuff. There is a velocity 'sweet spot' not too fast and not too slow, where every bullet design does it's best work. Just about all of them are designed for standard-length barrels, 20-24" and when we use significantly shorter or longer barrels, it is wise to take that into account.

I'll certainly be taking this into account for an 18" .308 Winchester that I will soon be building, when it is finished and I develop loads for it. If it was going to have a 28" barrel for example, I'd be using slower burning powder than I will be using for the 18" tube. Bullet selection will also be affected by the velocity for a given bullet weight that I will wind up with.

That is because barrel length directly impacts performance - and how to obtain it in a particular rifle.

Yes, Charles, that's all true. But at a maximum loss of 200 fps going from 24" down to 16" the actual loss of performance is really small in a hunting rifle shooting a sportsman's distance. Which was everybody's point. It's very unlikely you would ever notice any decrease in oenetration or expansion, because it's likely to be so small, its not even measurable.

My 120 grain A-max going 2715 from a 16.25" 6.5CM penetrate all the way through 220lb axis bucks at 300 yards. I don't know if you can penetrate farther than all the way through.

Quite true - if you credit the data that was presented. - I have my doubts about that data that "everybody's point" is based upon though, and would like to see a second, disinterested and objective test for that type of data.

Also: You do not know how "everybody" feels on this issue, you only know about a very small group from the total who happen to frequent this forum. - You do not get to speak for "everybody", by any means and it is best to keep that in mind.

My experience with military and tactical "experts" is that some of them will not hesitate for a millisecond to cook up bogus data, in order to prove some kind of bogus point or another. They also do not hesitate to latch onto and repeat bogus data for the same reason. I am seeing some of the behavior associated with that tendency here. The harassment posts, the character attacks... These are not typical of the behavior of thoughtful, open-minded and intelligent people whose opinions hold real value.

A good case in point about military arms evaluators drinking the Kool-Aid would be the .38 special... Many years ago, during the Boxer Rebellion in China, our troops found the .38 special service revolvers of the time to be ineffective at stopping the Boxer fanatics. At home, the Army soon afterward decided to run some "killing power" tests with different pistol cartridges, using them on live steers of the same size and weight. - And they did it right this time, early in the twentieth century.

They would measure and note how many rounds of a given cartridge it took to bring the steer to its knees, how many to get it down on the ground, how many to kill it. This kind of test would be hard to arrange today, but nonetheless it was a very effective way to gauge cartridge effectiveness in that era.

On the strength of those tests, the .45 ACP cartridge was chosen for use by our armed forces. - Because it offered a combination of effectiveness and other considerations that excluded more powerful rounds like the .45 Long Colt.

(Here comes the good part.) Decades later, political considerations surrounding the North Atlantic Treaty Organization caused the US military to reconsider - and choose the 9mm Luger pistol round, slightly less powerful and effective than the good old .38 Special, for all of our armed forces. In order to justify this obviously backward and counterproductive move, reams of bogus testing data and 'studies' by alleged experts made the rounds of the US military arms evaluation community.

- See what I mean?

For this reason, I am leery of any "data" that originates from military and ex-military personnel. - Especially those with a point to prove.

When I see data from an objective, disinterested party who can be trusted to let the chips fall where they may, then I'll be willing to take another look at long-standing data from a number of non-military sources that say different. - But that's just me.

Is my opinion so important to you that you just cannot stand it if I doubt that data?

Most adults encounter other opinions without trauma all through their lives. These days, when I encounter someone who just can't gracefully handle different opinions, I think of the lefty college students with their "safe zones", "trigger issues", and their fascist attacks upon free speech.

That kind of behavior is not impressive, not to me at any rate. - I see that kind of person as an uncivilized knuckle-dragger, at best.

We all have our opinions, and have a right to express them. This IS Texas, and Texas IS part of America, the land of the free.

I almost hate to weigh in on this discussion but it seems that if one wants a short barrel, they should go with it. Realize that you will lose between 20 and 45 fps/ inch dependent on many variables. Lots of folks want to push velocity to the max with that last grain of powder and this shouldn't be the desire if you are willing to give up the velocity offered by a longer barrel. That said sometimes a shorter barrel is more convenient and sometimes a longer barrel seems more stable. I have always found muzzle blast a big concern with shorter barrels but a can breaks that rule. I have several .308 rifles with barrels between 20" and 26". The 26 " barrel is the most accurate by far but it's a heavy contour. The 22" is the least accurate but it is a very thin barrel. This is a 6# rifle with scope and a pleasure to carry afield. The 26" and the 20" are very heavy rifles but they are very accurate and balanced well. As long as you know what the trade offs are, and are willing to admit the physics that control things, please indulge yourself in whatever barrel length you have talked yourself into.

Charles
Did you have a shop in Amarillo at one time in the 90s?
Serious question.

No, I have never resided in or near Amarillo. It's a nice town, but there are lots of nice towns and only one me.

A PM would be best for questions like this, by the way. That way the topic doesn't get cluttered up with irrelevant info.

A lot of the drama as opposed to clear thinking here about shorter barrels originates with those who own, or plan to own a can.

Prior to the recent popularity of silencers, one would have to search far and wide to find anybody who would contend with a straight face that shortening a rifle barrel would not adversely affect the ballistic performance of that rifle.

Note that Sir Hiram Percy Maxim, the inventor of the silencer, was not a strong proponent of shortening rifle barrels for use with his invention.

Here is a 30-30 set up as the one that he used to reduce garden pests around his home: (It may actually be his gun, the photo does not make this clear.)


Here is a Maxim silencer mounted on an 03 Springfield:


This not to say that shortening a rifle barrel when a can is to be employed is unreasonable. - Otherwise the gun's handling qualities are going to seriously suffer. - But it should be noted that there is no such thing as a free lunch, so the advantage to be had in handling quality must be weighed against the disadvantage in performance that shortening any rifle barrel entails.

My personal opinion is that silencers should not be regulated at all. They preserve the hunters hearing, and make it less likely that game will be alarmed when a shot is taken. Many of the deer for example that run when shot might not have done so if not alarmed by the rifle's report. The advantage of a can while pig or rabbit hunting, where multiple targets are often addressed should be obvious. There are some parts of the world where hunting without a silencer is considered to be rude and thoughtless... I'm not going to argue with that, it makes sense to me.

Smart hunters though should remember two things that Sir Maxim understood many years ago:

1. A standard length barrel does not require as big or heavy a silencer as a short barreled gun will, as there is less noise to reduce in the first place. - A glance at Maxim's personal silencers should make that as plain as the nose on your face.

2. A standard length barrel will give you better ballistic performance than a shorter barrel will.

I will add to this the recognized fact that people who are confident of their ideas do not experience a blood pressure rise when they encounter a differing opinion. - The learning process is not fossilized, and civilized behavior does not go out the window when there is some exposure to facts that do not support a pet theory or treasured belief.

I agree that shorting a barrel affects ballistics. However we are not talking about a dedicated long range gun. At the distance the opportunity is going to be using it at, it's a mute point. 200fps slower to 300 is only a few inches of drop and a couple for windage. It's not a big deal.

Not everyone likes a long barreled gun. That's great. It'd be a boring forum if we all agreed on everything. Hell,this forum would be pointless if we did. Not everyone will agree with you. Again this is a good thing.

I am in the planning stage of building a short bull-barrelled 308. (18") Do not confuse a factual statement about velocity loss with shorter barrels - with a blind preference for longer barrels.

There are purposes for which a longer barrel is definitely the way to go, but I am building with moderate range still-hunting in mind, maybe 50-250 yards. But most likely all shots will be at 150 yards or less. Some of this may well be happening in rough or heavily wooded terrain. So - I'm thinking of a short bull-barreled 308.

Where I live, a longer barreled rifle makes a lot of sense. - The high desert has no trees to speak of, in fact cover of any kind is not all that common. The animals here are tough, and include larger species like mule deer and elk. 200-300 yard shots at tough animals are not uncommon.

The rifle I am building though is not intended for the high Chihuahuan desert. I am building it with still-hunting the Texas hill country and hopefully the East Texas piney woods in mind.

Who wants to wave around a long barrel in thick cover?

If I were going to use something with a bit longer barrel, I'd probably go with a different cartridge. Something in 6mm or 6.5... But a larger bore size and a heavier bullet help offset the liabilities inherent in a shorter barrel.

Do you realize you just said basically the same thing I did? You are arguing for longer barrels while arguing for short barrels. You had a complete post on the superiority of long barrels. You have spent the majority of this thread demonizing short barrels, while saying it's ok if you do it.

Yes, it is amazing how a person can - if really determined - find a way to re-express what someone else has said to make it sound bad - even if it is something that they have just agreed with.

But facts are funny things, they still remain as facts, no how various opinions may try to obscure them.

And the fact still is, and will always be - that shorter barrels mean less velocity, while longer barrels will tend to give you more velocity.

And the fact still is, and will always be - that shorter barrels handle a bit better but can be loud, while longer barrels can really get in the way if you are in close quarters.

Yep...

20 inches of barrel seems about right to me, with a slightly heavier than #2 contour.

I have no regrets on getting the 16" barrel on my 308 AR. I gave nothing up on accuracy, only velocity and bullet drop, all can be corrected for. I like that it is lighter, and easier to move around inside the blind. I have the clicks wrote down on my scope cap at each range, and to me the loss of velocity was worth it. I can make the round faster if I want, but I don't find it necessary.