Barrel length versus accuracy

[flint]

Hi , I read an article about and indoors shooting range and in it the guy said that the most accurate lenght for any barrel was 21 3/4 inches and there seems to be evidence to suggest he just might know what he is talking about .. Now , I have found that the most consistantly accurate sporting (1255 fps) ammo here, in any rifle is "Wincheter power point" , and in the Reminton I am currently using is quite devastating ,how ever to keep in sweet with the neighbours where I have been culling rabbits , as you may have seen , I fitted a sound moderator which has increased ? the effective length of the barrel and the accuracy is not as good I was getting before ,also got to mention I am now using "Wincheter Subsonics"which also have a good reputation , so the question is should I shorten the barrel so that the over all length is 21 3/4 , change ammo brands , get in some more practice , just live with it ? .. Flint

[klsm54]

I doubt that shortening the barrel would give you any significant improvement in accuracy. I think that the "Sound Moderator" probably changed the barrel harmonics, thus possibly effecting accuracy. But shortening the barrel would be a crapshoot at best, trying to figure what the optimum length would be.

As far as 21-3/4 inches being the most accurate length...I would think that may be true over many barrel contours and weights, but there certainly are variables that could make a given barrel be more accurate at a different length, either shorter or longer.

I would try a few different brands of ammo, or try one of the aftermerket tuning devices before cutting the barrel.

[donnie]

Well said Scott!

[deputydon]

Something else that you did when you added the suppressor was change the balance of weight on you rifle. Which changes your hold ect...
Practice,practice, practice..... Remember sub-sonic rounds got there by going slower than the speed of sound.....
the only way I can think of to do that is LESS POWDER. which = less speed. Or maybe also a bigger slug. At any rate a way differant load than the power point round.

i am right about that ain't I guys??

[Jack]

I doubt that 21 3/4 (or any other number) is magic in terms of mechanical accuracy for a 22 rimfire.
Now, in the original article Flint is referring to- about an indoor shooting range....I wonder if iron sights were used. The longer the sight radius for iron sights, the more accurate- but that has nothing to do with the mechanical accuracy of the barrel, only the shooter.
I'd guess, along with the others, that the sound moderator has changed the barrel harmonics and the rifle's balance....
You also changed ammo, from the Power Point to the Sub Sonic- that could be it, too. Rifles show distinct preferences sometimes for a certain flavor of ammo.
I'd try some different ammo before starting in with the hacksaw... with changed barrel harmonics, the ammo preference could be different.

[Bill]

I totally agree with Jack. Any time you change volocity you also change barrel harmonics. Thats also the reason that Simms Vibration Labs came up with the donut that goes around the barrel of a .22 barrel. It either dampens the harmonics or changes the harmonics which will also change the accuracy of the barrel. I do think that something could be made that can do the same thing or give similar results. Something like wrapping tape around the barrel in different places will also do this. Where exactly you put it is a matter of trial and error.
Now as to barrels 21 3/4"s being the perfect length it also depends on the configuration of the barrel. Each one will vibrate differantly Heavy barrel, Sporter barrel etc. Maybe you could say that with a Heavy Barrel of X diamiter will shoot a bullet at X velocity and provide the best accuracy but to say that one certain length is best without describing a whole plathoria of other things to with it just isn't going to fly.

[jimiowa]

I can not disagree with anything said so far.

Flint have you ever been to Benchrest Central?
Very few of those guys shoot without a tuner.
Basically its a weight on the end of the barrel.
They use a sleeve with micrometer threads and a weight that screws on it. By experimenting with how far out on the threads the weight is. They tune the Harmonics of the barrel to the load they are shooting.
With your shop and the way you like to experiment, I am willing to bet that would be a piece of cake for you?

[jimiowa]

Another thought, I have read that a HV 22 reaches max velocity in aprox 16-18" of barrel. Beyond that friction and drag in the barrel would slow it down.
Now that would seem to suggest that a subsonic would reach optimum at a shorter length.
Finding optimum would vary from load to load so I have more questions than answers.

[flint]

Well thanks guys , I don't mind the extra questions raised ,you all know the saying (there are no dumb questions just dumb answers ) and I am not saying there have been any dumb answers .. I doubted the magic length theory too but needed to explore the idea , what I do know is that shortening a barrel by x amount will make what is left stiffer , that is per unit length .. If you don't grasp this (hell it was hard for me) here is a demonstration of the principle for you ..Get a 6inch nail and between the fingers of both hands bend it into a u shape , having seen how much you were out of shape get a 3inch nail and do the same thing , go on , the 3 inch nail is much slimmer you can bend it easy ,grunt puff jeeez I thought it would be easy wait I will have some more breakfast ..Ok I am not sure if that lot is relevant or not ,but you have given me more to chew over..I might just shorten the barrel anyway with the moderator on the front it sure looks like a long rifle ..Flint

[klsm54]

You are right flint. The shorter barrel will be stiffer. In theory, stiffer is more accurate, but not always the case in real life, back to that harmonics thing.

If the Sound Moderator is going to be a permanent attachment to your rifle, I would probably consider shortening the barrel also. If for nothing else to make the rifle somewhat handier and better balanced.

While there is no guarantees that shortening it will improve accuracy, I doubt that it would harm the accuracy. And no matter what the outcome of the shortening, you can still always use a tuner of some sorts if you still feel lacking in the accuracy department.

[calsibley]

My most accurate rifle has a short 20" barrel in .222Rem., but it also has a muzzle diameter of .960". Rarely do you see a benchrest rifle with a barrel longer than 21.5" They'd probably be much chunkier were it not for the weight restrictions imposed on them according to the class they are shooting in. Some of the rifles in the un-resticted class get up to around 28-30" barrel length, but you could hardly call them rifles since they often go as high as 20-25lbs.
Best wishes.

Cal - Montreal

[jimh]

flint i assume you're refering to the "Houston Project". i read that artical when someone posted it over at savage shooters. it would be interesting to take a say 26" barrel shoot a mess of loads through it and document the results then chop the thing down tot he magical 21 3/4" length and reshoot the same loads through it. don't know if it would prove anything but sure would be interesting to do.

[flint]

Hi jimh , soon as I saw your post I remebered , it was titled " Secrets of a Houston warehouse " it was interesting reading .. I just went and checked ,I used to sporterize #4 .303 Brit service rifles for my friends and to make them a bit handier and to get rib of the ugly foresite base I would cut offabout 2 1/2 inches which by coincidence brought the barrel length very close to 21 1/2 inches long and I must say all of those worked on proved to be very good shooters .. May be just another coincident I have a barrel that I just might try it out on , when I get time ,just don't hold your breath ..flint

[calsibley]

If I recall the Houston Warehouse shoots it was done in the evening after the workday ended, back in the '80s.. The place was converted to a temporary shooting range. Several benchrest records were set, but they were all ultimately disallowed since it was an artificial environment with no wind, no mirage, only ideal conditions. Shooters were almost dying for the honor of shooting there. It was only operational for a year or so, and to a very few shooters. There could have been more than one warehouse building being used but I doubt it. I've read about it on benchrest.com Best wishes.

Cal - Montreal

[jimiowa]

I too remember reading that report.
It was facinating in that by shooting inside a building you had controlled conditions and could exclude any wind interference. As I recall all rifles were 6ppc and the writer attributed much of his success to loading techniques. As I recall all bullets were seated by thumb pressure.
So I would conclude that the writer could very well be right if one were dealing with a 6PPC centerfire.
Change the caliber and its back to the drawing board?

The Centerfire shooters can tune the harmonics of their barrel through their loading techniques and various loads.

With a rimfire, the uncontrollable constant is the ammunition. There fore Tuners are a viable option, not seen with Centerfires.