Tuning Custom Kral Bighorn .357

[thammer]

Bighorn is ready to hunt. 28" hammer forged TJ 1-26 twist barrel. Reduced the poppet size. Opened up the valve throat. Enlarged the dropblock port. Bored the hammer spring hole and running a Benjamin Bulldog spring with spring guide. Custom thick walled shroud and an M18x1 endcap to fit a Donnyfl suppressor. I'll update the thread once I get the spring dialed in and shots on target. These are still really best suited for pellets and sub 90gr slugs. Should be in the 160fpe range once I've gotten everything tweaked.

 

[CyberDyneSystems]

Very interested to see how it performs. I imagine I will be wanting to order one once you are able. I love the idea of big (ish) bore with a magazine vs. single shot.

 

[darylm]

That thing definitely needs a 700cc CF bottle on it.

 

[thammer]

That thing definitely needs a 700cc CF bottle on it.

I agree. 

 

[Vetmx]

That’s an elegant cannon. I’m not a big bore guy but I am enamored by them. Can’t wait to see some shot strings and what it likes.

 

[thammer]

That’s an elegant cannon. I’m not a big bore guy but I am enamored by them. Can’t wait to see some shot strings and what it likes.

Thanks. I used to have this barrel on a Kral Mega doing 180 fpe. It was about 3" longer then. Had to cut the leade off and remachine to fit the Bighorn breech since the barrels are a little larger diameter. Grouped well back then with just about everything I tried in .357 hoping that stays true with this setup as well. 

 

[Airgunmann]

Nice work got my recluse 357 up to 200 fpe but it's declining string only get about 3 shots with 125 gr slug but a air hog and loud using AAO valve and transfer port plus a heavy hammer and spring the original valve and spring I had it to 180 fpe for about same shots AAO valve is about the same as my modded original valve but it uses quite a bit bigger transfer port and have to open up the receiver that's definitely a nicer set up than my single shot recluse interested in hearing some numbers and shot string good work

 

[thammer]

Initial testing

7 shot tune in the 930s avg

10 shot tune in the 910s avg

14 shot tune 880s avg

Very pleased. On to paper next. 

 

[Vetmx]

Are you happy with how the gun sounds? I remember a video of you shooting indoors with an unregulated gun that sounded very crisp. You have to move a lot more air with a .357. Just curious if you can keep that crisp without a reg.

 

[thammer]

Are you happy with how the gun sounds? I remember a video of you shooting indoors with an unregulated gun that sounded very crisp. You have to move a lot more air with a .357. Just curious if you can keep that crisp without a reg.

Actually sounds really good. Only running a 60gr hammer so seems pretty efficient. Obviously louder than my small bores but not that much more. 

 

[Ezana4CE]

How does it like .35, 82 grain H&N Grizzly hollow point slugs?

 

[thammer]

How does it like .35, 82 grain H&N Grizzly hollow point slugs?

I've not tried them in it. I've yet to find a gun that likes them. I do have some so worth a shot. 

 

[thammer]

Final tune

3500psi start
3000psi end

10 shots

890
895
897
898
896
897
895
891
905
892

With JSB 81gr 

 

[CyberDyneSystems]

Well that looks promising!

 

[thammer]

Well that looks promising!

Hended to the range with it tomorrow. If it prints as well as it chronographs it will definitely be a winner. 

 

[CyberDyneSystems]

Any update?

 

[Wian357]

hi, awesome gun. any idea where i can get my hands on one of those barrels?

 

[Trekkerx]

Thebestairgun.com

 

[Wian357]

Thebestairgun.com

Thanks emailed him and he said he only sells it with the gun not sperate.

 

[rafajpg]

How does it like .35, 82 grain H&N Grizzly hollow point slugs?

I do have a KRAL BH 357 and it is a pellet gun those do not like slugs as they come with choked barrels, I tried NSA slugs and blew the Orings on the barrel.