TargetTalk

I was using technical specs from Midway USA's website listings of the ammunition. Looks like there is some variance.

Apples and oranges. Right, you cannot compare ammunition velocities published by different manufacturers, and especially when they were measured using different barrel lengths. I have chronographed Lapua Super Club and Pistol King with my Pardini SP (120mm barrel). The muzzle velocity is almost identical for both, about 910 fps.

Idiomatic expressions in a foreign language...

I should have gotten it right though, with all the american and english TV we get over here.

Oh well, at least I don´t translate swedish expressions all too often ;-)

"no danger on the roof"
"not much to hang in the christmas tree"

Sorry for going off topic

/Anders

FWIW, here are some actual chronograph tests of several types of mid and premium .22 brands though my Pardini. (Excel file)

Hope this helps in an apples-to-apples fashion.

Keith

Interesting that some of the tested brands do not make (on average) the minimum 250 m/s velocity required for 25 m Rapid Fire - although all except the Eley Blue Pistol Match have, in the sample tested, at least one shot that exceeds the minimum. A couple of brands are marginal and another test sample might average less than 250 m/s (822.9 fps).
Rapid Fire competitors might want to chronograph their ammo before heading off to a competition where the ammo will be tested.

According to Steven Boelter in his Book "The Rifleman's Guide to Rimfire Ammunition", CCI Blazer chrono'd at 1306.5 fps out of his Ruger 10/22 with aftermarket barrel. His data is a few years old, but I wouldn't have thought CCI's load for Blazer would have changed that much. I guess we'll have to have someone on the board chrono some current production Blazer to know for sure.

http://findarticles.com/p/articles/mi_m ... i_n8709803

In this article the author claims that .22 velocities reach their peak speed coming out of around a 20" barrel. According to the author, the standard test length barrel is 24" and since he is primarily talking about CCI ammunition and talked to CCI representatives, we can assume that their published data comes from a 24" barrel.

In the small chart halfway down in the article, we see that CCI Standard Velocity (which CCI claims has the same velocity as the Blazer at 1070 fps) has considerably less velocity coming out of shorter pistol barrels such as the M41 at 959 fps.

It's not really a mystery, muzzle velocity as a function of barrel length is explained by Le Duc's equation of internal ballistics:

V = ax/(b+x)

Where V is the muzzle velocity, a is the maximum muzzle velocity (i.e., as measured with a barrel of optimum length), and b is a constant related to the bullet's position in the barrel at the point of maximum pressure.

As implied in some of the posts here, in no way can you just say that ammunition X has a muzzle velocity of Y. It is a meaningless statement unless the barrel length for which that velocity is measured is also given. (Some manufacturers do this, however, they give muzzle velocity with no mention of the barrel length. They certainly have this information, they just don't care to advertise it for some reason.)

Yes, optimum barrel length to maximize muzzle velocity is in the order of 20 to 26 inches or so, the exact length being a function of the specific ammunition and the characteristics of the barrel.