Kral Jumbo project. Some observations.
- Thread starter Vetmx
- Start date
Oh yeah I completely spaced out that with a reg you can’t use the gun fill port. What reg did you use?
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How did you you make your moderated shroud and where did you get your barrel from or did you cut it and re-crown it?
Will you let us know what the chronograph results are in this configuration?
Is a video possible, I would to get a idea of the sounf and accuracy?
This is a interesting build, I really like want your doing with your build. By the way I have a Jumbo also.
Lol, I know you love the jumbo can up front.
Will you let us know what the chronograph results are in this configuration?
Is a video possible, I would to get a idea of the sounf and accuracy?
This is a interesting build, I really like want your doing with your build. By the way I have a Jumbo also.
Lol, I know you love the jumbo can up front.
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I don’t mind my can but it’s that ping that bugs me. I thought about pulling the bottle and stuffing a sponge into the bottle.
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Do it and post the results. My buddy has an Air Force International Orion. Its very similar in design to a Marauder but 20 times more accurate. It is unregulated so it pinged like a 500cc two stroke dirt bike. It also hammer bounced like a blacksmith. I fixed the hammer bounce with a short stiff spring. He ordered something from Robert Lane for the ping. It was a little ball of steel wool or something. we pushed it down his air tube and it worked. The whole gun sounds much better now and he likes to shoot it. He didn't before. I say go for it. Then deal with the little Harlem Globetrotter bouncing around in your receiver.
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Tonio, I'm sorry if I didn't get real in depth with this build. I know this is primarily a FX/Edgun/Daystate/ you get what I'm saying forum. I just brushed over the stuff I did building my brother-in-law a gun. I don't mind sharing more if someone is interested. My silenced shroud consists of an air stripper/baffle mounted one inch from the muzzle, then a felt wrapped curler, then a Delrin washer, then another felt wrapped curler, then my end cap. I machined the air stripper, washer and end cap out of Delrin and so the curlers lock into them. I also made a bushing with an oring that screws on the end of the barrel to center the shroud. That bushing has holes in it to vent air back the length of the shroud. My barrel is a Kral barrel that I cut the receiver end off and machined it to fit. I wasn't cutting the choke off, I want this to be a pellet gun. I ported the gun to 3/16'. The valve is not a 3/16 hole straight down through. Its more of a sweeping hole towards the front of the gun if you get what I'm saying. The TP wheel was very tricky to get right because there isn't much material to work with. I just kept working at it until I was able to drop a 3/16 bit down through the top of my receiver all the way to the valve. My barrel had to be oval ported. When I seated a JSB 18gr and pulled the barrel, I had vey little room to enlarge the barrel port forward without exposing the pellets skirt. That's a big no no so I just took it as far as I could the oval ported it. I set the reg at what I hoped would be 130b, but it settled in at 140b according to the Kral gauge. Max power with the short barrel at that reg setting had the JSB 18's going in the 850's. The 14.3's were in the 930's and too fast. The gun also didn't have a clean report so I just kept shooting through the chrono until the gun produced a nice clean snap. The 14.3's were at 915fps and the 18.1's just under 830fps and the 15.89's are at 880fps. I could jack the reg to 150b because I know I have the hammer spring to do it but I don't need the gun any faster. 114+ shots on the reg makes my compressor very happy. As far as sound goes, your gun is a Harley Davidson with drag pipes compared to mine. Trust me, I put 100 pellets through mine when I first got it and I was using the same Donny and a Huggett. Hope I answered all your questions.
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Vetmx, thanks for elabrating on your project. You differently put in the work I'm sure your brother in-law is going to love it.
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I am having second thoughts about leaving it with him. I really like shooting it. It’s light but not so light that it moves around when you shoot it. It’s been a while since I put time in behind a truly comfortable gun. We all convince ourselves that our bullpups, or any tactical style guns are comfortable, but they really aren’t compared to a traditional rifle. It is just so easy to shoot. Especially now that all the vibes and noises are gone.
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https://youtu.be/2pXNxObyMPo
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" />Here is a video I did on adding a regulator to a bottle gun like the Kral Puncher Jumbo. Just be careful to not drill the transfer port wheel to thin. I actually made one from a steel bolt. I made the TP adjuster on a drill with hand tools. easy enough to do. hope this helps
https://youtu.be/2pXNxObyMPo
Your videos is what got me to go for a Kral puncher jumbo. I noticed in one video you said you where wondering if there are any machinists out there willing to try and make a replacement block that has a regulator built into it. I am a machinist and think that would be a fun project.
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I like the detent for holding the TP wheel wide open. I had to put a mark on mine so I know where max flow is. 
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Hey JTknives, I'm glad the video was helpful. As for creating a regulator block for the Kral series of guns Im not sure it is worth the labor. It could be an interesting endeavor but it will be just that, an endeavor. There are some many projects that I have on the table that have me bogged down. I was more hoping Kral would incorporate a regulator into there some of there guns even if they shoot pretty flat.
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I just watched the video. I built my first reg cover out of aluminum and was having a long debate on how to secure it when my friend said just make it out of plastic pipe. Now I know where he got the idea. He is a Youtube educated man. I should have known. As far as integrating a reg into the block is concerned, it would be great for keeping the gun compact. The problem is R&D. An in-line reg is very precise because of how the air pressure acts upon it. Getting a tiny one to function precisely in the bottle block would probably put their guns price point where they are no longer appealing next to the competition.
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I considered getting a .25 if I couldn’t get a 22. After being in the gun, I’m glad I didn’t. I could barely port the 22 big enough to have a shot at a nice efficient tune with a reg. Because of the TP wheel, the max I could go and keep all the ports matching was 3/16 or 4.7mm. That is not enough for a 25cal. Thebanker4, what do your shot stings look like in .25 with that choked off porting?
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I just ran across a regulator and shoud modifier this on the net. What do you guy's think of these to products. There's no price on the regulator.
http://pcpspares.com/?s=Kral+Nemesis+&post_type=product
http://pcpspares.com/?s=Kral+Nemesis+&post_type=product
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The reg can’t be added to your cart so I imagine that’s a no go. The shroud thing looks like it can be purchased. If you don’t mind making your gun even longer, I say buy it. It allows your gun to have a functioning shroud and will reduce sound and eliminate the beating your factory shroud takes with each shot.
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It's been a while since I have shot the Jumbo but from memory its about 59 fpe with 34 grain for 25 shots with a 20 ES. I know its not super stable. I do get an occasional shot that spikes for about 20 fps but at 880 fps it not terrible.
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I think that giant 20 ES reflects not having big enough porting. There's not much you can do. My porting on my .22 is on the anemic side but adequate.
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