Tuning Flashpup S Refurb .177

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Cdoo333

Cdoo333

Member
Jan 31, 2021
18
1
CT, United States
So I purchased a flashpup s refurb in .177 and have been having some accuracy problems. The crown on it looked a little crappy so I've re-crowned it with only a slim improvement (pic below). From maybe 4 inches at 25 to 2 or 3in depending on the pellet. Now I'm wondering if it's shooting too fast?

Its shooting around 905 with 10.3gr and 960 with 8.44gr. I have a huma regulator installed and am wondering what pressure and speed I should be targeting. It's currently set at 115bar and I didn't run it stock. 

This is an affordable project gun that I got it to tinker with. Already had to replace the check valve oring that had a leak develope after the first couple of fills. Have any others with a flashpup or flash models had accuracy problems? What pellets and speeds do they run well at? I know every gun is different so I'm going to have to do some more tinkering. This evening I've already dropped the reg to 100 and reset the hammer the whole way in cw to test out later in the week when I get a chance. I should also state that I cleaned the barrel well when I first received it and I have about 300 pellets through it. Let me know what you guys think. 



PXL_20211012_011004647.1634086527.jpg

 
850FPS Is what I always shoot for, both in .177 and .22 and come to find out I think 25cal is the same way as my best 25cal groups are coming in at 850 or so FPS also. 

https://hardairmagazine.com/buyers-guides/ham-recommendations-most-accurate-177-caliber-pellets/ 

I have a Hatsan Flashpup synthetic sidelever refurbished also, but mine is in 25cal. Mine looks like Hatsan re-crowned the barrel for me, I thought maybe that was the issue it was sent back for in the first place. I put a regulator in mine also. I don't exaggerate my groups at all, if anything I try to round up, but my Flashpup is shooting sub 1/2" groups at 25yds so I know the gun is capable. 


 
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My brother in law has a flashpup s in 25 with a reg also and gets pretty nice groups at 25yrds. Pretty much one hole. It's one of the reasons I got this one in .177 so I can make him look bad with a tinier pellet when we go squirrel hunting :]

I'll have to try it how it is currently with the reg at 100bar. Maybe it's too low but I'll try to get it sorted for 850-880. Id like to get a tune where I can use both heavy and light pellets accurately. Maybe I'll try to do something like 830 for 10.3gr and 880 for the lighter 8.44gr and see how that works out. 
 
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Jumping from 8.4’s to 10.3’s is a big swing. If you’re going to hunt with the gun leave the 8.4’s for a springer or pistol. They can be a last resort if the gun refuses to shoot any pellets in the 10+ grain range. But you will have to back the gun way down. My BSA Ultra shoots the 8.4’s unbelievable at 830fps. I’m more interested in your porting. An unregulated gun has choked off porting to keep the shot string in check over a broad psi range behind that valve. You need to open your ports to what a .177 regulated guns ports are. Once the gun is breathing properly you can back the reg down and relax the shot cycle of the gun. Then you might find your hammer spring is way too much because you no longer have to smack the valve so hard. If your porting isn’t right, the whole gun is way out of whack. But you should still see signs of accuracy. While you’re checking your port sizes, you’ll have the barrel off. That’s a good time to examine the leade or chamber and see if it’s wrecking your pellet before it’s even sent down the barrel. Remember, sticking a reg in an unregulated gun doesn’t make it a regulated gun. It’s only a half regulated gun. In a lot of cases it’s just a mess. Most never realize it.
 
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There are a lot of good points in your response vetmx. Thank you for taking the time. I fired a few shot strings over the chrono in the garage and it seems that at 100bar with the 10.3gr I'm getting around 840fps with the hammer adjusted the whole way cc. I'm assuming the hammer and or spring are too strong for 100bar. Any adjustment CCW doesn't change the fps very much. I think I'm going to disassemble it again and try 110. That should get the 10.3 around 880ish. 

The distance I was shooting at wasn't far enough to tell if the groups tightened up. I'll explore enlarging ports if there is some accuracy that comes into play with this next tune at 110bar. Otherwise I may be calling hatsan USA for a new barrel. I'll check in next time I have an update with some targets. 

Thanks again for everyone's suggestions and experiences. 
 
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You seem to be skipping a whole step in tuning a regulated gun. What is the max speed your gun will shoot the 10gr pellets at 100b. We know what the minimum your hammer spring will produce when backed all the way off. You need to turn it CW until the gun tops out and record that speed. It’s actually the only speed that matters right now. Not your minimum speed. Oops, never mind. I didn’t see the tiny cc when I read it the first time. You still have an issue though. You need to set the reg so your max speed it 920fps. Then pray you can back off the spring and hit 880. If you can’t, you need to go spring shopping. 
 
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PXL_20211016_130014526.1634432875.jpg


Yeah so at 20 yards shooting with the reg at 110b about 890fps, groups are still pretty bad. The next adjustment will be 120b reg maybe slower at around 850fps. The lower left was fx 10.3gr which where better than the others that were crosman piranha 10.3gr. Every 3 or 4 shots it will throw a pellet. The sd isn't too bad maybe 10- 15 fps, but this could be better. Still have some tinkering to do. 
 
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No gun will shoot a Piranha but you should see some sign of accuracy with the FX 10.3 or a H&N Baracuda. If your leade and crown look good I would seriously try to get another barrel. Once your groups start to look good you need to check them ports. I just sold a .177 with a 15” barrel. I had the ports at 3.5mm and it easily spit 10.5’s over 900fps with the reg at 110b. Save the Piranhas for shooting over the chronograph. Never use them to judge a guns accuracy.
 
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The random 3rd or 4th shot is what's puzzling.. Since it's with each pellet I'm wondering if this barrel just doesn't like being close to 900 at all (+-30fps). With the reg bumped up to 120b maybe I'll be able to run it lower at 830-850ish. This is kind of a bummer because I wanted this .177 to really fling them. My shooting buddies have other hatsans and even flashpups that shoot great. I still have hope for this one and it's just taking some time to iron out. I wonder if the choke is too tight at the end of the barrel?
 
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Sometimes the leade is just cut too deep or the barrel is junk. Really flinging a .177 usually ends at 900fps depending on your standards. All my super accurate 177’s are below the 880 mark. Like I keep saying, a smooth shot cycle due to lower reg setting and less required hammer spring tension because your gun has adequate porting goes a long way when it comes to accuracy. 
 
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Vetmx I get what you're saying about the porting. However I'm not going to waste the time modding ports / barrel if it isn't accurate. Also it would be adding another variable to the mix of trying to get this thing sorted out. I reached out to hatsan USA and sent them some pictures of the groups. I may try lapping the barrel if they are going to send me a new one and I don't have to return it. I'll shoot a few pellets into a milk jug to see what the rifling looks like.
 
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