The curved barrels of Big Gun cannons also add back-spin. Very accurate, left-right, even through sloppy over-sized barrels, but not particularly precise vertically. A few years ago, I did some penetration testing with a Big Gun torpedo cannon and various thicknesses of armor, and determined that a 1/4" cannon at maximum legal power and not skipping off water will penetrate any legal thickness of balsa at up to 30 feet. I couldn't gather data on further ranges because I couldn't hit my test target at further ranges. The vertical inaccuracy was too great, and after 20 tries to land a hit, I gave up. At 30 feet, though, I nailed it on the 2nd try
If you have to fight at long range, make sure you're throwing a lot of steel. The individual odds are poor, but your chances of at least one hit go up quite a bit.