I just dug out my chronograph and ran the JSB 33.95gr 25cal over it. My kral puncher jumbo is only pushing them at 660-670fps. The bottle is full and I played with the lower adjuster but that was about all I could get out of it. This seams rather low compared to what I was expecting for it to put out. The accuracy seams to be great but I feel I should be getting more punch from a gun called “puncher”. I know I have seen people talk about opening up the ports but I have not researched it. I’m a machinist so doing the needed mods is not an issue.
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Puncher Jumbo with low velocity.
- Thread starter jtknives
- Start date
That's not so uncommon. That puts you at almost 800 fps with the 25.4gr Kings, polymags or hades. The 25cal Kral guns are just 25cal barrels and bolts on a 22 cal gun. Porting and hammer mods will get you mid 800s or better with the 33.95 JSB. If you can find a 3650psi bottle upgrade that will do even more for you. 50 shots at 50fpe should be a minimum goal.
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The 22 caliber is perfect. 25 caliber is already going past it's design and efficiency. The HATSAN would be a better choice if power was most important to you but probably wont be as reliable as a Kral.
I would just stick to the 25gr Kings if you plan on keeping it. The Kings are excellent pellets even out to 100 yards at 800fps. It's harder to shoot any hot rodded screaming gun accurately as opposed to ones that's at factory set power levels unless it's a 177.
I would just stick to the 25gr Kings if you plan on keeping it. The Kings are excellent pellets even out to 100 yards at 800fps. It's harder to shoot any hot rodded screaming gun accurately as opposed to ones that's at factory set power levels unless it's a 177.
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The 25cal just needs the porting, hammer and springs to match the power output needed. If correctly ported it even handles 30 cal well. It's a clone of the evanix rainstorm/blizzard. Plenty of room for power.
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Was looking into it and why not just remove the power adjustor and seal the openings with threaded plugs.
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I have no use for the power wheel and replace all mine with 1" SS 5/16-18 cap head screws from Home Depot. They work perfect. I remove the existing power adjuster and ream and tap the hole for the bolt then install it and drill the transfer port size I need. For 25cal I like 13/64" and can produce in excess of 70fpe but typically run 55-60fpe with the JSB 33.95 JSB.
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So you can port the barrel on a .25 to 13/64" and not expose the seated pellets skirt? My .22 didn't have that much wiggle room.
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Since it's a pin probe the depth of your pellet skirt will determine final pellet seated depth but even if there's a tiny bit of skirt exposed the air will go through the gap behind it and push the pellet clear of the transfer port way before any damage would occur. It's never affected accuracy. On my .30 builds I go 1/4" TP valve to barrel. I've even taken a lot of 22 cal to 13/64" with zero issues.
EDIT: Just tested with 22cal Hades and still clears the 13/64" TP
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I didn't know what pellet my gun was going to like so I checked JSB 14,3, 15.89 and 18.1. I was too nervous so I just oval ported the gun. I never exposed a pellets skirt before but its good to know that you haven't noticed it messing with accuracy.
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Here's what I noticed THE MOST when modding to max out the power not only Krals but other guns too when you back it down it shoots crazy calm like better than factory smooth.
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I have no use for the power wheel and replace all mine with 1" SS 5/16-18 cap head screws from Home Depot. They work perfect. I remove the existing power adjuster and ream and tap the hole for the bolt then install it and drill the transfer port size I need. For 25cal I like 13/64" and can produce in excess of 70fpe but typically run 55-60fpe with the JSB 33.95 JSB.<img data-src="
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I’m guessing you tap both sides of the action and thread a cab screw into each hole and have a gap between then bigger then the transfer port size?
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I have no use for the power wheel and replace all mine with 1" SS 5/16-18 cap head screws from Home Depot. They work perfect. I remove the existing power adjuster and ream and tap the hole for the bolt then install it and drill the transfer port size I need. For 25cal I like 13/64" and can produce in excess of 70fpe but typically run 55-60fpe with the JSB 33.95 JSB.<img data-src="
" class="lazyload" src="data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==" /><noscript><img src="" />
I’m guessing you tap both sides of the action and thread a cab screw into each hole and have a gap between then bigger then the transfer port size?
No, the bolt is 1" and fits flush with the other side of the breech. Goes all the way through then drill the transfer port down from the top through that bolt.
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Why not keep the power adjuster and replace it with a larger diameter allen bolt ? E..g. 8 mm easily allows a 5.5mm transfer port. I made one, the only tools used were (my limited) brain, some patient measuring, a power drill, an iron saw, file and fine grain sandpaper ...
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I am trying that out. Picked up some grade 12 8mmx70 Allen head bolts and turned one out. Looks like it will work very well.
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