Can't wait to get my converted 2400kt back and compare it to my disco in terms of fps & fpe.. using all disco internals, modded gauge port etc with a 17in barrel...
CO2 is difficult, because the numbers change with the temperature.... I've seen the article about the optimum barrel length being about 20-21" for CO2, but that hasn't been my experience.... or Crosmans.... They list the 8" barrel 2240 at 460 fps.... the 14" barrel 2250 at 530 fps.... the 18" barrel 2250 XE at 550 fps.... and the 24" barrel 2260 at 600 fps.... I've found those numbers to be quite accurate at about 70*F (except for the 24", 580ish is more like it).... I've played with the spreadsheet, and it also predicts ever increasing velocities with barrel length, right up to 30".... The change in velocity is very small at the longer lengths, and greater with carbine lengths, just as you would expect.... It is very large at pistol lengths, going from 8" to 10" gains about 30 fps.... The more you mod it for power, the more important a longer barrel becomes.... Here are the spreadsheet predictions, starting from 580 fps on a 24" barrel (ie a stock 2260).... Note that you lose twice as much velocity with a 10" barrel as you do with a 14.5" barrel.... 24" - 580 fps - 10.7 FPE18" - 557 fps - 9.9 FPE (9% loss)14.5" - 535 fps - 9.1 FPE (15% loss)10" - 489 fps - 7.6 FPE (29% loss)8" - 459 fps - 6.7 FPE (37% loss)I played around with the spreadsheet to get it to agree with some known data points (mine and Crosmans).... In no way did it predict a "magic" barrel length shorter than 24".... I suppose that for a given combination of a tight pellet and low temperature there might be such a thing, but I've never seen it.... Incidently, by the time I got to the above set of numbers, the 2240 was experiencing a "dump shot" which means the pellet is leaving the barrel while the valve is still open.... Ever wonder why a 2240 is so loud, and why you can often see liquid CO2 coming out, especially if you are shooting uphill?.... With a 10" barrel, the valve is closing just as the pellet leave the muzzle.... After that, increasing barrel length sees expansion of the CO2 in the barrel after the valve closes.... The gun gets quieter and more efficient as a result.... Modding the gun to increase power and CO2 consumption means even a longer barrel for best performance.... Sorry, but the same rules apply as for a PCP.... especially if you mod your 22XX.... Bob
I've never tried that specific setup.... but I just built a 1740 with a 10" barrel (otherwise stock) and it shot in the 560s-570s at room temperature.... I have a 1750 with an 18" barrel, and when it was stock, at the same temps, it shot in the 630s.... To me, that looks like about 8 fps per inch.... I'd lose the heavy hammer spring, you'll probably find it SOUNDS more powerful but it's only wasting CO2....Bob
Advertise Here
Share This!