Barrel Length Discussion

[crb]

I understand that part of the reason that longer bbls are used is to keep the velocity down. If not for the minimum legal bbl length of 16" could it be better to have a bbl short enough so that the velocity was what was desired ? I know one of the Heplers has a BR pistol [with a 15" bbl I was told].

I wonder if the ES is better with a long bbl or a short bbl ???

Ray

 

[John Kielly]

Ray,

Projectiles travelling subsonic are less effected by wind than those travelling above the speed of sound, but the faster a bullet travels, the less it will be displaced by wind. So, competetive rimfire shooters of all disciplines try to get their ammunition going as fast as possible without it hitting supersonic speed.

It has been found that ammunition be loaded right on the speed of sound (& that varies depending on atmospheric conditions) can sometimes end up with a stray one here & there that goes just that bit faster. As you surmised, longer barrels do cusion those peaks somewhat - sort of slow the rounds down a tad & cushion the peaks - & that's one of the reasons for longer barrels. Back 10 years or so when I still shot smallbore, we found hereabouts that the newly-marketed Federal ammunition was too quick for the newer Anschutz rifles with the short barrels & long bloop tubes (to get the sight radius - another reason for the longer barrels) & depending on the weather, up to 1 in 2 would go supersonic. It was a hoot when it screwed up those guys' groups but the crack of the hot shots tended to put the rest of us off our strokes too.

John

 

[crb]

You see a lot of position rifles with bbls around 19". I have a bbl on my BR rifle that is about 18.5" or so and the velocity of the best ammo averages 1140 at app 5 feet from the muzzle [ Eley black box, 1069 vel ]. Just over the speed of sound, 1125 @ 68 degrees.

To me behind the gun it sounds just like all the other guns on the line, no definite crack. Maybe it is louder to the other shooters but nobody has commented on it. It seems to shoot pretty well but is very wind sensitive. I still haven't found the definitive tuner setting which may help the wind bucking.

Since I am unlikely to find some 1040 to 1050 velocity ammo what if I started shortening the chamber end until I got the velocity down to 1080 to 1090 at the muzzle? Even if I had to go less than 16" [ I would create a 'pistol' to be BATFE compliant ].

Somewhere I read a comment that the currently available ammo is still too fast for best accuracy because of it being borderline supersonic in many bbls. What say yee ?