My anti-slug gun Neutron Star

I picked this gun up for $530 out the door direct from Hatsan in .177 caliber.

I could not get the gun to group like I wanted. Besides that I really only like .177 for plinking (wadcutters).

Aside from that what really stood out is how long the gun was. And QUITE front heavy. Making it less than ideal for woods walking and off-hand shots. The barrel and shroud were getting very close to 2lbs. And at 24" were really making the gun feel very heavy. 

I almost never use slugs. Ever. Most of my shots are between 20-70 yards. So, I decided a short, thinner barrel was in order. Enter the 16" TJ pellet barrel with 12.7mm OD. Factory is 16mm OD.

There is now an air stripper in a functional carbon fiber shroud. Factory shroud is 4mm thick steel, and is not utilized whatsoever for dampening report.

I also sourced a 1.75-10x24 scope that is a hair under 1lb.

Huma moderator @ 2.7 oz

Total weight is 8.8lbs. 

I also tuned the hammer spring to make the shot cycle much more pleasant. (not using original spring) The factory setup on these is frankly a bit absurd.

Believe it or not, this gun is setup to run Crosman 14.3gr HP pellets. This gun has been shooting them like a laser. To my shock. At ~$6.50/500 I'll take it! I have plenty of JSB pellets, but no need to run them in this gun. 

Another thing of note. The magazines from this will work in my FX Crown. So, I was able to get my hands on a FX Crown single shot tray and fit it to this gun pretty easily. If you've used a hatsan tray, you'll know why I didn't want to. 

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That's a wicked tune! I've been pretty impressed by these gun's (hatsan pcps in general) to deliver high power, and quite flat ES. I've got a Sortie that has an ES of 15 (for about 24 shots) across 100 bar.

The Neutron was good out of the box. Just would not group like I felt it should. And I have no real need for high FPE. So, mine is currently running a restrictor. And extremely light hammer spring ~15fpe with a shot count of ~300 give or take 😂 So, I feel like I really did take this in the opposite direction hatsan intended.

I know the Crosman pellets I'm using will not work well with higher power levels, as well. They don't seem to like 800+fps or somewhere there-abouts. But, I'm going to take the restrictor out tomorow, and put a heavier hammer spring in it to see how it behaves (with JSB 18.13s). I think I did massage the valve on it. But have not massaged the barrel port yet.

I left 1 screw out of the gun that had no structural purpose I could see. It basically made it so you couldn't pull the reciever off the hammer/trigger tube without removing the valve and bottle (I think I recall?) Anyhow, The way I've got it, removing 1 screw under the magazine, and the other behind the cocking lever, both easily accessible, allows the whole top to pop off, and you can swap transfer ports. 😎
 
Question about changing the hammer spring out/in? Can you share you steps?

I have a .22cal NuetronStar, got it for $660 new from MidwayUSA with a birthday discount!

Gun is setup to shoot 23gr. H&N slugs (.217dia) @ approx 850fps. I need to double check that speed, it might be closer to 880? It's very very accurate out to 200yds (with minimal winds of course :)), a few weekend's ago I shot a 10 shot group at 200 in a slight cross wind the size of a dollar bill. Then my next shot was at a 16oz pop can filled with water. Got it! Perfectly center! The H&N slugs don't expand, but are accurate. Would like to try the 25grs. Next, but will need more juice I think?

I originally shot the 22gr. FX hybrids @ 940fps, but i think the hammer spring relaxed, speeds dropped down to 915fps (accuracy wasn't a good, that's how I knew).

Maybe there's a way to double up the springs? To get more force? Maybe that's a bad idea? I'll need a new spring to be able to shoot those hybrids again @ 940 or even to get more fps out of the 23gr H&Ns.

Any help will be greatly appreciated!

Thanks

Cliff
 
Nothing better than a gun that will never see a slug. It will live a happy, stress free life. I did the same thing to a Kral Jumbo. Installed a reg, chopped the barrel, lightened the hammer, built a SSG and made a shorter functioning shroud. Since you built the shroud, why not put in a little more work so you can ditch the can. You only have a 16” barrel but are still sporting the goose gun look. I think you have enough room left in that shroud to make it happen.
 
I actually like that idea. Ive still got some of that carbon tube, so I think what I'll do is 3d print some end caps and guts, and make a small baffle stack to go on the end. 

The gun is actually shorter now. The original 15.5" tj barrel got trashed when I tried to get it threaded. I got to talking to rallyshark, and we figured out the flash barrels are a direct fit.... He happened to have a .22 14.25" LW threaded barrel for his flash that wasn't being used, so the gun is back in business.

Ironically, I have also been shooting slugs with this gun using the original .177 barrel. I polished it up, and actually got jsb monster rds shooting hole in hole at 880fps using the same tune I was using for the short barrel. Go figure. It wouldn't shoot for anything when I got it, but the port was way out of alignment on it, and the tune was probably horrendous. 
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😎 Very cool, guys. Aside from missing the regulator on mine, I think our three look like they could be family, haha. I know the parts and machining are better on the kral and the evanix.

@Vetmx What type of finish is on your stock? It looks like a real nice factory finish, but I know they don't come like that. I spent a good bit of time on mine and still need to polish it up more. If you look at really any nova star, you'll notice the cheek riser is a completely different piece of wood and doesnt match at all. It took close to 10 tries, lol. But I did get mine to match almost perfectly 😎 Real happy with that.

I need more time and ammo to check the power curve. But this is what it used to be with 14.3 CHPs Pressure reading corresponding with the bottom FPS reading

Upon installing the shorter barrel I was at 845fps with the same pellets. But going from un-choked TJ to choked LW, not too much of a difference.

I should note this shot string was shot using pellets from the tin. Running these 14.3s thru my pellet sizer (when I chose to) shows a wide range of head sizes, and several always have damaged skirts too, so I recon that would account for some of the lows and highs.

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Here's how I've been shooting it lately. I printed a stippled thread protector to save a couple grams. And the gun has a port restrictor in it. So, ~650fps? Problem is that the power curve is much flatter without a TP restrictor. I'll be switching to a lower dual scope ring setup once they show up. I'll also be trading the bipod for a sling :)

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I have a 25 Nova Star (same gun). I happen to have a buddy who is a Hatsan wizard and he did a valve mod and tuned mine to shoot 60 fpe for 60 shots with a 20 fps ES. It's super accurate and shoot the 34 gr MK2 and NSA about the same.
So I have a question about this tune. Was this done with or without a regulator. Also does your friend take on other guns to tune. I also have a .25 neutron that I would love to be tuned like this.
 
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So I have a question about this tune. Was this done with or without a regulator. Also does your friend take on other guns to tune. I also have a .25 neutron that I would love to be tuned like this.
It was done without. The factory valves in these guns are in a way, self regulating. They have multiple exhaust ports that exit in 360 degrees. It's my theory that the many ports exert restrictions and turbulence on eachother having some regulatory affect on discharge or airflow. I can't remember exactly what I did, but I am sure that I did take considerable force out of the hammer. Not sure if I reduced hammer spring tension significantly, or if I cut it any. I believe I just reduced the tension a lot. Left the ports completely alone.
 
It was done without. The factory valves in these guns are in a way, self regulating. They have multiple exhaust ports that exit in 360 degrees. It's my theory that the many ports exert restrictions and turbulence on eachother having some regulatory affect on discharge or airflow. I can't remember exactly what I did, but I am sure that I did take considerable force out of the hammer. Not sure if I reduced hammer spring tension significantly, or if I cut it any. I believe I just reduced the tension a lot. Left the ports completely alone.
So this is interesting to me. I’m still trying to figure out how you’re achieving 60 shots per fill and still maintaining 60ftlbs of energy. Heck I can only squeeze about 25 good shots. So if I reduce the hammer spring tension then I can get close to you have?