The Bighorn might fill the gap in the unavailability of a bottle Evanix. Allows for a slightly heavier hammer and a lot more spring due the lengthened action. I'm running Benjamin Bulldog springs in mine with a 60gr hammer. 20 shots at 85fpe in 25 with a 22.8" barrel. Perfect candidate for a 28" TJ 257 barrel swap. Is already full bore ported in 25. Comes with a 500cc 250bar bottle.
Quote from: TroyHammer on November 18, 2021, 04:50:34 PMThe Bighorn might fill the gap in the unavailability of a bottle Evanix. Allows for a slightly heavier hammer and a lot more spring due the lengthened action. I'm running Benjamin Bulldog springs in mine with a 60gr hammer. 20 shots at 85fpe in 25 with a 22.8" barrel. Perfect candidate for a 28" TJ 257 barrel swap. Is already full bore ported in 25. Comes with a 500cc 250bar bottle. 85 fpe is nowhere near enough for .257. You want at least 140 fpe or preferably 160 fpe to get those 257420 & 257388 bullets up to speed. That's doable with Evanix Blizzard and Sniper X2 bottle gun but if Kral only makes 85 fpe in .25 it seems rather low for that. Then there's the issue of barrel support, Bighorn has rather short length of breech that supports the barrel and the rest is free floating. When you attach a 28" or rather a 30+" .257 barrel to that it will whip and quite a lot. In my Blizzard which seems to have longer breech support for the barrel than Bighorn, I had to install a barrel band with no o-rings to get good accuracy. And as for good accuracy I'm referring to sub 1" groups at 100 yards. If I was to build a .257 from scratch I'd seriously consider Kral as a starting point but it really needs to make more than 85 fpe in .25 to make it feasible. If there's not enough hammer strike you can always use a 2mm valve stem to make more valve dwell.
Quote from: rkr on November 18, 2021, 11:59:58 PMQuote from: TroyHammer on November 18, 2021, 04:50:34 PMThe Bighorn might fill the gap in the unavailability of a bottle Evanix. Allows for a slightly heavier hammer and a lot more spring due the lengthened action. I'm running Benjamin Bulldog springs in mine with a 60gr hammer. 20 shots at 85fpe in 25 with a 22.8" barrel. Perfect candidate for a 28" TJ 257 barrel swap. Is already full bore ported in 25. Comes with a 500cc 250bar bottle. 85 fpe is nowhere near enough for .257. You want at least 140 fpe or preferably 160 fpe to get those 257420 & 257388 bullets up to speed. That's doable with Evanix Blizzard and Sniper X2 bottle gun but if Kral only makes 85 fpe in .25 it seems rather low for that. Then there's the issue of barrel support, Bighorn has rather short length of breech that supports the barrel and the rest is free floating. When you attach a 28" or rather a 30+" .257 barrel to that it will whip and quite a lot. In my Blizzard which seems to have longer breech support for the barrel than Bighorn, I had to install a barrel band with no o-rings to get good accuracy. And as for good accuracy I'm referring to sub 1" groups at 100 yards. If I was to build a .257 from scratch I'd seriously consider Kral as a starting point but it really needs to make more than 85 fpe in .25 to make it feasible. If there's not enough hammer strike you can always use a 2mm valve stem to make more valve dwell.85fpe is with a full 20 shots. It will do a lot more power wise but at the expense of shotcount. There's plenty of hammer strike. I'm no where near max potential at 85 fpe. That's with a single hammer spring and the adjuster almost all the way out. As far as barrel goes there is no issue. Just make a new fitting at the rear of the shroud towards the breech longer to accommodate the extra barrel length and it will remain a tensioned barrel just like the factory barrel is.
Quote from: TroyHammer on November 19, 2021, 12:52:15 AMQuote from: rkr on November 18, 2021, 11:59:58 PMQuote from: TroyHammer on November 18, 2021, 04:50:34 PMThe Bighorn might fill the gap in the unavailability of a bottle Evanix. Allows for a slightly heavier hammer and a lot more spring due the lengthened action. I'm running Benjamin Bulldog springs in mine with a 60gr hammer. 20 shots at 85fpe in 25 with a 22.8" barrel. Perfect candidate for a 28" TJ 257 barrel swap. Is already full bore ported in 25. Comes with a 500cc 250bar bottle. 85 fpe is nowhere near enough for .257. You want at least 140 fpe or preferably 160 fpe to get those 257420 & 257388 bullets up to speed. That's doable with Evanix Blizzard and Sniper X2 bottle gun but if Kral only makes 85 fpe in .25 it seems rather low for that. Then there's the issue of barrel support, Bighorn has rather short length of breech that supports the barrel and the rest is free floating. When you attach a 28" or rather a 30+" .257 barrel to that it will whip and quite a lot. In my Blizzard which seems to have longer breech support for the barrel than Bighorn, I had to install a barrel band with no o-rings to get good accuracy. And as for good accuracy I'm referring to sub 1" groups at 100 yards. If I was to build a .257 from scratch I'd seriously consider Kral as a starting point but it really needs to make more than 85 fpe in .25 to make it feasible. If there's not enough hammer strike you can always use a 2mm valve stem to make more valve dwell.85fpe is with a full 20 shots. It will do a lot more power wise but at the expense of shotcount. There's plenty of hammer strike. I'm no where near max potential at 85 fpe. That's with a single hammer spring and the adjuster almost all the way out. As far as barrel goes there is no issue. Just make a new fitting at the rear of the shroud towards the breech longer to accommodate the extra barrel length and it will remain a tensioned barrel just like the factory barrel is. Ah, OK - I thought it was a max power tune. .257 is a few shots gun only if you shoot those heavy bullets at high speed, that's why most people shoot them tethered. Evanix do not tension their barrels, what's the Kral tensioned setup like and could you do it for a TJ liner?