12.5" vs 18.5" Barreled 10/22 Velocity test

Very informative and interesting results with the short barrel having higher velocity. My guess is with the 10/22 blow back system. The casing leaves the chamber when the bullet reaches at around 14"-16" in a 18" barrel so any energy thats left escapes out into the action and the last few inches of barrel actually slows the bullet down. I bet in a bolt action. The longer the barrel the higher the velocity.

The bullet is long gone before the chamber opens. Anything different would result in a face full of high pressure gas every shot.

Mark
 
In a blowback system, the bolt starts to move backwards while the bullet is still in the barrel. It must, as the pressure that is acting to push the bullet down the barrel is also acting on it and nothing is locking it in place. However, it has much higher mass than the bullet and a spring behind it, so the rate of movement is going to be much lower. And the dampening delays that movement in the beginng. You aren't getting a face full of gas because there is still a seal between the mouth of the case and the chamber when the pressure is at it's highest.

The case does not get ejected until after the bullet leaves the barrel. This can only happen because the bolt is still moving using the momentum it gained while the bullet was still in the barrel.

Even in delayed blowback centerfire system, the bolt begins to move before the bullet leaves the barrel:
leverdelayedblowbackani.gif
 
Excellent visual teaching aide. Thanks Kombayotch!
I still prefer a bolt to a blowback. I find it easier to concentrate when there aren't all those moving parts ...... moving. It makes enough noise these days when my body parts move.
 
I really thought the CCI Velocitor where suppose to be much faster than all the other brands of ammo. Very good info to know, all though not conclusive but very great. Thanks again for taking the time.

Maybe the velocitors powder burn rate would be more advantageous in a pistol lenght barrel. Look at his high figures in the 12.5 and relatively slow in the 18.5. It would be nice if someone could do a velocity check of those velocitors against other high velocity, in say a ruger 5.5 inch barrel. I'm guessing they may be surprisingly fast from the pistol.
Their claim of 1435 in standard lenght rifle barrel is far from what surfclod obtained.

Great testing surf, thanks for your time and ammunition.:canadaFlag:
 
Mark White of SoundTech cut down a .22 rimfire barrel inch by inch and found the most efficient length to be about 10 inches. This would confer with the OP's 12 inch results.

Where is the data showing the 16 inch length is the best? Or is this just "one of those things everyone knows?" There is a lot of bogus information flying around the internet that is just plain wrong but because it gets repeated over and over again, everyone takes it as gospel without ever bothering to check it out for themselves.

I suspect the 16 inch length is derived from the US law on short barreled rifles where the minimum barrel length is 16". Meaning it is a legal issue that has nothing to do with the physics and mechanics of the actual rifle and ammunition.
 
Where is the data showing the 16 inch length is the best? Or is this just "one of those things everyone knows?" There is a lot of bogus information flying around the internet that is just plain wrong but because it gets repeated over and over again, everyone takes it as gospel without ever bothering to check it out for themselves.

I suspect the 16 inch length is derived from the US law on short barreled rifles where the minimum barrel length is 16". Meaning it is a legal issue that has nothing to do with the physics and mechanics of the actual rifle and ammunition.

http://www.rimfirecentral.com/forums/showthread.php?t=32426&highlight=chief+dave+22+velocity+barrel
 

OK, fair enough but that is one guy's test. Hardly scientific or a great body of data and certainly not proof that 16" is the "best" barrel length.

I went back and had a look through the data published by Mark White. He tested 5 different types of ammo in two different rifles (10-22 and 77-22).

The results are less than conclusive. There is no single barrel length that gives the highest velocity with all ammo types. Basically the range of barrel lengths that tend to produce the highest velocities is 14" - 18". There was even one combination where the 20" barrel produced the highest velocity.

Looking at the data a bit more closely it is obvious that the 14" and 16" lengths produce the same number of "highest velocity" combinations.

One other thing to note is that the velocity difference between a 16" barrel and a 20" barrel is generally only about 10 fps or so. Which hardly seems worthwhile to hack 4" off your barrel to gain only 10 fps.
 
Here's something on CCI Velocitor regarding barrel length and muzzle velocity:

Just how fast were Velocitor bullets moving? Chronographed velocities were taken the next day. My Oehler 35P showed a high reading of 1,409 fps, with an extreme spread of only 35 fps. This is less than the promised 1,435 fps average, but can be explained by my test conditions of 60 degree temperature and a 28-inch barrel. Speer's published velocities were taken indoors at 70 degrees and from a 24-inch barrel -- about the optimum length for maximum velocity with a longer-burning powder of the type used in the Velocitor.

I found it here:
http:// findarticles.com/p/articles/mi_m0BQY/is_12_48/ai_93317487/
 
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There's also this in regards to CCI Velocitors:

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: Linda.Olin@ATK.com
FAX (208) 799-3589

It can be found here:
http://www. thehighroad.org/archive/index.php/t-158192.html
 
I think you can hardly ever get anywhere near the claimed velocities of most hyper marketed ammo.

FWIW, here are some velocities I've gotten from my 10/22 in the past, compared to yours:

Remington Thunderbolt
12.5 barrel 1288.9 FPS S.D. 14.8 FPS
18.5 barrel 1103.1 FPS S.D. 85.2 FPS
18.5" Factory 1178 FPS S.D. 58.5 FPS

Remington Subsonic
12.5 barrel 1091.2 FPS S.D. 18.6 FPS
18.5 barrel 969.4 FPS S.D. 55 FPS
18.5" Factory 1098 FPS S.D. 28.65 FPS

Federal 525 Value Pack (36 Grain plated HP)
12.5 barrel 1254.1 FPS S.D. 21.1 FPS
18.5 barrel 1195.7 FPS S.D. 28.0 FPS
18.5 Factory 1259 FPS S.D. 58.51 FPS

CCI Velocitor
12.5 barrel 1348.3 FPS S.D. 35.4 FPS
18.5 barrel 1177.9 FPS S.D. 86.8 FPS
21” Winchester 77 barrel 1240 FPS S.D. 37.48 FPS
4.5" Norinco M93 955 FPS S.D. 42.8 FPS Just for curiosity's sake

I have actually gotten faster velocities from Win Experts than from the Velocitors out of my M93:
Win Expert 985.5 FPS S.D. 28.33 FPS
CCI Velocitor 955.0 FPS S.D. 42.81 FPS


Your shorter barrel might indeed be faster than your factory Ruger barrel, but I believe so many factors can influence velocity, that the mere difference in length here might not be the whole story. Other factors like actual bore diameter and bore smoothness can also affect velocity. Ruger's barrels are well known for their roughness and yours may actually be tighter than your 12.5" barrel.
 
Maybe the velocitors powder burn rate would be more advantageous in a pistol lenght barrel. Look at his high figures in the 12.5 and relatively slow in the 18.5. It would be nice if someone could do a velocity check of those velocitors against other high velocity, in say a ruger 5.5 inch barrel. I'm guessing they may be surprisingly fast from the pistol.
Their claim of 1435 in standard lenght rifle barrel is far from what surfclod obtained.

Great testing surf, thanks for your time and ammunition.:canadaFlag:
The FPS from the test results are probably lower than the standard results because the quoted stats are based on standard temperature, pressure, wind, etc. The colder weather and low air pressures slow down the burn rate of the propellant, reduces the ballistic co-efficient of the bullet, and results in lower velocities then quoted.

I think that at 5.5 inches there's considerable loss of pressure that will result in lower speeds than a 12.5 inch barrel. I'm speculating this purely on an observation I made a few months ago while fooling around with an Iphone4 and a stop-motion app at the range. The stop motions showed us that a SW model41 pistol had a considerably larger muzzle flash compared to a 22" anschutz 190 rifle. My assumption is that a larger flash indicated more powder being burnt outside the barrel than inside, resulting in lower pressures exerted on the bullet.
 
The FPS from the test results are probably lower than the standard results because the quoted stats are based on standard temperature, pressure, wind, etc. The colder weather and low air pressures slow down the burn rate of the propellant, reduces the ballistic co-efficient of the bullet, and results in lower velocities then quoted.

I think that at 5.5 inches there's considerable loss of pressure that will result in lower speeds than a 12.5 inch barrel. I'm speculating this purely on an observation I made a few months ago while fooling around with an Iphone4 and a stop-motion app at the range. The stop motions showed us that a SW model41 pistol had a considerably larger muzzle flash compared to a 22" anschutz 190 rifle. My assumption is that a larger flash indicated more powder being burnt outside the barrel than inside, resulting in lower pressures exerted on the bullet.

Yes the temp on my day of testing was 5-9C, much lower than an average room temp that most factory testing would be done at; also were conducted at about 3500 feet, not sea level. All minor factors but they can add up.

After getting my chrony I test nearly everything I can find, including archery and power tools (air nailer:p) I have found that ammo rarely meets factory claims, not saying they are lying, just that common sporting firearms and conditions are rarely optimized like their test guns are.


As per your pistol vs rifle comparison, not only muzzle flash but how about muzzle report??? My dads 12.6 revolver with its 2" barrel is brutally loud but a 24" bolt is very mild, perfect for gopher shooting with others and not needing hearing protection.
 
My results last summer,shot over my Chrony

velocitors
4.5 inch colt huntsman- 1088 fps
6.75 inch browning challenger-1206 fps
20 inch winchester 9422-1381 fps

CCi mini mags 40 gr
4.5 inch-1055 fps
6.75 inch-1126 fps
20 inch-1201 fps
 
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