SmallCaliberCentral

Saturday my friend and I went out to check the sighting on our rifles. I experienced something that was hard for me to believe.

The friend has a CZ 223, with a 40 grain VMax, has the velocity of 3750 fps. The barrel is 22" long. So while at it, we both wondered what kind of velocity that would give in my Douglas barreled 223 at 27" in length. We were both shocked as my Sako only registered an average of 3450 with three shot. Both rifles were shot at the same distance from the chronograph and both were fired 3 times. He even went back and shot the CZ again to make sure there was nothing wrong with the chrono. We shot his ammo.

Five inches less barrel length and his was 300 fps faster. I have never seen that much variation in velocities and I have been doing this a long time.

Lenard:

That is remarkable! And, very interesting.

However, I recall an article or experiment, where the testers started with maybe a 26 inch barrel, and progressively lopped off an inch at a time, and kept very good records of the results. As I recall, it was a .204, and the peak velocity was attained at something less than 26 inches.

Perhaps someone else remembers this. The info may have even been on this site.

Yes, the article is on this site, under .204 barrel length. However, your result is very unexpected.

stevecrea wrote:Lenard:

That is remarkable! And, very interesting.

However, I recall an article or experiment, where the testers started with maybe a 26 inch barrel, and progressively lopped off an inch at a time, and kept very good records of the results. As I recall, it was a .204, and the peak velocity was attained at something less than 26 inches.

Perhaps someone else remembers this. The info may have even been on this site.

I believe this was done by Bullberry! There has been an ongoing discussion on another forum I frequent about this same subject and the .17 HMR.

For those of you that are interested, I think I have figured out the answer to why the 27" barrel shot 300 fps slower than the 22" barrelled CZ.

The powder we were using is DP2200, a powder developed for the short barrelled 223 military guns. The only logical reason I can come up with, is the powder burns in 16-18". Any arguments for or against this theory?

Lenard