ORIGINAL: stubblejumper
Stated velocity is 3060 fps with 24" barrel, how much slower do you think my gun shoots with 22" barrel.
Velocity varies with chamber dimensions and barrel dimensions as well as with barrel length.You should be somewhere between 2900fps,and 3000fps,but without a chronograph,you are only guessing.
Stubblejumper is essentially correct. As a rule, with a cartridge with the expansion ratio of the .270, we say you can expect to lose bertween 25-30 FPS per inch that you chop off. A magnum case like the 7mm Rem Mag the loss goes up to the vicinity of 50 FPS/inch.
HOWEVER: All rifles don't lose the same amount, and
in some cases, people have reported a GAIN in chronographed velocity after shortening a barrel! Bottom line: Stubblejumper said
"chronograph it." That is the only way you'll ever know about your specific rifle.
I once owned two Mannlicher-Schoenauer .270 carbines. I used the 130 and 150-grain Nosler Partition bullets in them, with 55.5 and 53.5 grains of IMR 4350 respectively. The 130-grain load chronographed 2880 FPS, and the 150 made 2820 FPS from both guns. Both had 20" barrels with 1/9" twist. Both shot into 1.25 MOA, and were very deadly little rifles. I would not feel handicapped having to use a .270 anywhere in North America, nor for non-dangerous game in Africa.