Optimum barrel length for .22LR

[grimjaw]

I figured this would be a more appropriate topic for the rifle forum.

What's the optimum barrel length for getting the highest velocity out of the .22LR cartridge? I realize it will depend on the specific cartridge, but let's hope I can generalize to say *most* .22LR cartridges. I shoot CCI Stingers more than anything else, if that helps.

jmm

 

[pauli]

it's my understanding that 22lr tends to peak around 18" or so, and past about 20" loses muzzle velocity. stingers are necessarily pretty hot, however, and may do alright with more barrel.

 

[sumpnz]

I read (I think) on Varmint Al's website where they did a test on .17HMR ammo with a test barrel that started out around 26" and was cut back in 1" increments to about 10". Velocity peaked between 18-19" and dropped off on either side. I imagine a .22lr would peak at an even shorter barrel length.

I seem to remember reading somewhere that with most .22lr's the powder was fully burned by like 16", and velocity probably peaks before then rather than after.

 

[knzn]

After hanging out over at rimfirecentral.com for the past couple of years the consensus seems to be in the 16" neighborhood for .22LR. For optimum speed that is. The accuracy debate will go on forever.

 

[grimjaw]

The accuracy debate will go on forever.

That was my second question. If shorter barrels (16"-18") allow maximum velocity, what do you get from 24"-26" barrels you see on some rifles: accuracy? Longer sight radius for open sights I understand, but does it do anything to stabilize the ballistics?

I think at this point I better start picking up physics books.

jmm

 

[pauli]

sight radius is about it; making sure all the powder burns inside the barrel does make things slightly quieter and cleaner as well, though, i suppose.

 

[Shear_stress]

On open sight guns, those very long barrel lengths (26" and such) make sense to me. What I don't completely understand is when people fit their 10/22 with very long barrels that lack iron sights. Maybe the noise reduction really is what they're after.

 

[rust collector]

Many high-end smallbore target rifles now sport a bloop tube, a sleeve over the muzzle of a 16" or so barrel that allows hanging the front sight out a ways while releasing the bullet to go on its merry way with less chance of being influence by gun movement.

Seems to work. Haven't put one on my old model 37, however .

 

[Don't Tread On Me]

Well....


For max velocity for a normal high-vel 22LR would be 16.5" of length. After that, it slows down.

Stingers are an issue. They have a longer case, so they are "hotter" loaded. They also have a smaller bullet. This is purely a guess, but I'd say the stinger could probably make use of a longer barrel due to being a hotter cartridge.


Green Mountain makes a Stinger barrel that is reamed for the Stingers longer length, and it's 18". It also has a slightly different twist rate to properly stabilize the lighter and faster projectile. Stingers tend to not be very accurate at all. With the Stinger barrel, people have reported near MOA accuracy.

 

[MTMilitiaman]

So I have a 20 inch bull barrel on my 10/22--are you saying velocity might actually be less than with the standard barrel? I could maybe buy that with the standard velocity loads like the American Eagle 38 gr JHP I feed it a lot, but what about my choosen varmint and small game load--the 40 gr CCI Velocitor. They seem loaded a little hotter by .22 LR standards. I think CCI advertises them at over 1400 fps...

 

[pauli]

you could just email cci.

 

[Carl N. Brown]

.22 barrel

From what I have heard-
- The Remington Nylon 66 was designed with a 19" barrel
because that length gave the maximum velocity with
Remington highvelocity .22 long rifle (in 1959).
- The CCI Stinger is the only current .22 cartridge that
gives higher velocity in barrels longer than 18" out to 26".
- With most brands of .22 long rifle peak velocity and
muzzle blast is in the 16" to 18" barrel length range.
- .22 long rifle must be loaded to give acceptable
velocity in both short pistol barrels and rifle barrels
so six to sixteen inch barrels give useful ballistics.
- In the days of black powder and Lesmoke (a mix
of BP and smokeless) longer barrels (24" to 26") did
give higher velocity.

In my own .22 rifles with barrel lengths of 16" 17"
20" 22" and 25" the practical difference is hard to
notice.

 

[hksw]

Maximum speed = maximum accuracy?

Hmmm, I don't know. Its hard to argue against 21"-27" Anschütz barrels.

 

[MTMilitiaman]

Wow that was fast...

This afternoon I wrote to CCI with my questions and already received a reply, which I have included below:

Robert
The test barrel length CCI uses for testing, both Pressure and velocity and
accuracy, is 24". This is the industry 'standard' for 22 LR barrel length per
SAAMI.

When I asked our lead technician your question he stated a 18-20" barrel length would be optimum for most of our 22 LR products, especially the Mini-Mag group, parts #30 and #31. It is possible a longer barrel may gain you some velocity when using our CCI Velocitor ammunition. Our Rimfire R&D Engineer has stated that it (Velocitor) was designed for best results in a 22-24" bbl. We get very good accuracy results from Velocitor in our 24" barrels but Mini-Mag 22 LRHP, part #31 is a consistent top performer for us also.

Linda

Linda Olin
CCI/Speer Technical Services Technician
1-866-286-7436
Ext. 2343 E-mail: [email protected]
FAX (208) 799-3589

I have to give CCI kudos for the fast an informative reply, esp to an email

 

[grimjaw]

MTMilitiaman, thanks *very* much for the post. I guess my next question is:

What about .22WMR?

jmm

 

[JohnBT]

"Maximum speed = maximum accuracy?"

No. Longer barrels do slow the .22LR bullet down a little. Target ammo is just barely subsonic and you want to keep it that way even if the powder charge is a hair too high or temp/humidity/altitude conspire to give your shot a little too much speed. With .22 rimfire you want the bullet to stay below the speed of sound to achieve the best accuracy. If it starts above the speed of sound and falls below it on the way to the target you've got trouble because it gets bounced around as it drops below the speed of sound. IOW, as it slows the shock wave catches up to it.

John

Speaking of shock waves, here's a pic. Condensation cloud as F/A-18 Hornet flies at or near the speed of sound.

 

[thales]

*


One good reason a longer barrel can contribute to better accuracy is that it allows the propellant gas to cool off and the pressure to decrease before the bullet exits the bore. That way, gas cutting of the bullet is reduced. Off-axis tipping of the bullet caused by any possible minute asymmetry in the muzzle crown is also eliminated or reduced.


*

 

[MTMilitiaman]

Yeah what he said...