Military rifle barrel length

[jon lynn]

Once in a while I look at the gun rags that feature military assault rifles. The thing I notice most is they seem to have shorter and shorter barrels. Does this have a large effect on long-range accuracy? I mean in Iraq it all is close contact, but when they see one of the enemy weenies in the distance, wouldn’t a longer barrel, with a bit more twist, help the 5.56 round to get a human target?

I never liked the M16-A1, I never made expert, but when we got the A2’s life was 100% better at the ranges. My CO told me the rate of twist and heavier barrel helped stabilize the new heavier 5.56 round. I asked him if length helped anything? He answered honestly and said he did not know.

I don’t mess with in depth calculations like most reloaders and varminters do, I just do factory ammo, me and reloading could be a very bad thing………...really

[Dan Morris]

Jon, I have always contended that longer barrels and larger rounds are more accurate..JMO.Shorter and lighter AR's are designed for spray and pray....I'm old school, accurate aimed fire has gotten more people out of a jam than fire power. Larger bullets have more knock down power/wind resistance and longer barrels offer a longer sight radius.
This, of course, is just my own opinion...
Dan

[Jack]

The barrel length isn't the major factor in bullet stabilization (within reason), rifling twist is. Given the proper twist for the bullets being used, the 14.5 inch barrel of the M4 should work as well as the 20 inch barrel of the M16, at any reasonable range.
Velocity will be reduced in the 14.5 inch barrel compared to the 20 incher, with the same ammo.
I spoke about this very thing with a friend of mine who's currently in the Army. His comment was that the M4 is vastly easier to maneuver in and out of the vehicles and aircraft that troops ride in these days- like the Bradley, Humee, and helicopters. That handiness of the M4 would help in house clearing type situations, too.
As far as accuracy, with iron sights like military rifles of old used, a longer sight radius provided by a longer barrel would give, at least in theory, a bit more accuracy than a short barrel....BUT.. they don't use iron sights on US rifles any more. Currently the standard military rifle sight is a red dot type, or holographic sight, or even a scope, where barrel length is no factor at all on accuracy.
The net effect of the 14.5" M4 barrel as compared to the 20" M16 barrel is a little less velocity, so a touch less bullet energy.
Actually, with the enhanced sights, I suspect the M4 is a little more accurate than the M16 in the hands of the average soldier.

[Gil Martin]

These folks have given sound advice. I tend to prefer longer barrels and heavier bullets. On the other hand, I have seen shooters use ARs on the 100-yard range shooting the National Match Course and turn in spectacular scores. Probably the difference is practice, practice and more practice. All the best...
Gil

[BILLY D.]

Jon

Back during the 'nam conflict, otherwise known as the SEA War Games the army started the Squad Sniper concept. These guys were the best of the best. Excellent shots and a dedicated rifle, usually an M-14, specialized.

Can short barrels be accurate, you bet they can. However the military is not going to invest big bucks in rifles that will get the barrel shot out in a few rounds due to the before-mentioned spray and pray of close quarter combat conditions.

Dpms and Rock River Arms produce rifles that will make you drool at their group sizes. 1/2>3/4" groups are common with these firearms.

The whole issue comes down to the almighty dollar. Uncle Sugar ain't gonna invest in rifles that shoot that well just to be shot out in a few hundred or so rounds while utilizing spray and pray techniques.

Just to put this in perspective. If you owned a super big magnum rifle would you go to the range and shoot 30 rounds rapidly with it and not let it cool down during the session? Of course not but in combat you don't have that choice.

As for Iraq I don't have a clue as to what derivative of Sniper Rifle they are using so I can't comment on that.

Best Wishes,Bill

[spike1]

I just posted this on another thread ?
I'll stick it here also ?

I can’t recall exactly what publication had it? ??? American Gunsmith or Gun Test Magazine possibly ???? As I remember it the discussion was with the 17 HMR when it was 1st released. The discussion centered around the best barrel length. Seems they cut one and re-crowned it. They tested it for speed and accuracy then they started cutting it down shorter and shorter. Seems like the answer was surprising like the speed increased as they cut down to 17 inches and the accuracy didn’t change. After 16(?) inches the speed started to slowly drop off. I remember I had to read it one word at a time to make sure I understood what I was reading. The data confused the author also and they repeated it on another caliber 308? 30-06? or 270 ??? don’t remember,,, but got similar results. Seems like 18 to 20 inches would be all the longer you would want to be.
Many factors effect accuracy. It has been my amateur opinion and observation that shorter barrels seem to be more tolerant to varying loads and types of ammunition just as heavy barrels seem to be. Shorter or stiffer barrels have less harmonic whip,,, I guess. That just my opinion and I don’t know jack,,,, or jill.

[Jack]

Spike, the small rimfire cartridges (small in powder capacity) often give maximum velocity in around a 16 inch barrel. Reason for that is, there just isn't much powder to burn, so the powder is all burned in a relatively short barrel.
That is usually NOT true in centerfire cartridges with a larger powder capacity. In most of the typical centerfire cartridges, like the 270, 30-06, 30-30, barrels longer than 20 inches will almost always produce higher velocity than barrels under 20 inches.

[spike1]

Ok, I took the Chrony out today. I had my 10 FP with a 24 inch barrel and my new AR with a 16 inch. The 16inch AR was averaging 2744fps, and the Savage with the 24 inch was averaging 2987. So the longer barrel was doing 243fps faster. Sure wish I had something around 20 and 26 inches to see if it is a linear increase or did it go past it’s peak. If it is somewhat linear it would be about 30fps per inch

[BILLY D.]

spike 1

You are also comparing apples to oranges when you put a semi auto against a bolt action. To be completely non-biased a test such as that should be performed with the same firearm and start with a 30 inch barrel and cut it back one inch per shot and chrono measured at each shot.

There will always be differences when two firearms are used. Guns don't have ballistic twins.

Best wishes, Bill

[spike1]

Good idea Billy !

How soon will we have the results?

[BILLY D.]

Originally posted by spike1
Good idea Billy !

How soon will we have the results?

spike

As soon as you ship me YOUR firearm to test. I sure ain't cuttin' up my Krieger and Pacnors.

Bill