What?!? 😟 Slugs Give Me LESS Muzzle Energy than Pellets?

By the way, about the result from adjusting the hammer spring, I wanted to point out the initial tune actually looks like it was adjusted nicely for shooting medium to heavy weight pellets. The 810fps setting represents right at 95% of the 850fps maximum and that's pretty much right where it should be. Somewhere in the vicinity of 95% - 97%. Kinda refreshing to see it adjusted like that from the factory  

Thank you all for your comments and help!!




I have done it and jumped down the modding rabbit hole.
Today is a first for me. Never opened up a gun before. Not really a mechanic/ technician, either. But hey, here we go!
Hopefully I won't mess anything up too bad — in the country where I live there seems to be no capable gunsmith for airguns....

I adjusted the trigger pull, and routered the access to the HST screw of the Skyhawk.





Then I chronied the Baracudas:
810fps = 30.8FPE




Then I turned the HST screw all the way in till coil bind (3 and 5/8 turns from the position I received the gun at).
And chronied again:
853fps = 34.2FPE





Now, that is plain disappointing.
That's all that the HST gives me, lousy 3.5FPE (43fps)?
I expected a whole lot more power increase — looking at Bob's very helpful article in HAM.
The graphic there gave me hope that I'd be able to up the power much more with only the HST....
https://hardairmagazine.com/wp-content/uploads/2019/03/HAM-2-Pellet-Weight.jpg






Well..., it didn't work for this gun, I guess.
Now if I understand this power tuning business correctly, I'd need to increase the setpoint(?) of the regulator from (I think) 140bar to 150bar, or more, and mess again with the HST.




That means, degassing (I handpump), and disassembling the gun even more, to get to the regulator.... (Not being a pro-tinkerer like many here on the forum I wanted to avoid that....)






O well, tomorrow at the cow farm range I'll see what the other slugs will do that I haven't tested yet.
And maybe I find the silver bullet after all, without messing with the reg (or worse, getting an extended plenum, for an extended sticker price....).

Matthias

Hello Matthias, for my experience, with a standard stem and valve, the best regulator value for p15 is 130 or 135 bars, 

i make test on mine, and even with a 70cc plenum the best value for my reg is 135 bars, tested with upper value and the speed decrease, test first to set to 130 or 135 if you're like mine this is where the combination of spring valve and stem work the best

Thierry

Click to expand...

The lighter slugs, let's say 19gr, won't be as accurate as the heavier slugs because they (the lighter ones) are shorter.

The 19gr I tried were horribly inaccurate, like 4" groups at 50yds. They spiraled like crazy and could barely hold 12" at 100yds. The 21gr were not as bad.

The 23gr were way better for accuracy.

The 22gr FX Hybrid slugs are very accurate......they are light weight but very long. They have the stability of a heavier slug due to their design.

There’s much more to it than just length of the slug. There’s the barrel that you are using, the speed that you are shooting, the weight of the slug, the base geometry (flat, dish, cup) and more I’m sure. And the only way to know is time and effort experimenting. 
Case in point, I was shooting my .22 EDGun R3 Long yesterday, which is a Laser with the 25.4 grain RD Monsters at 935 FPS. So I set up at 50 yards with slugs. All NSA.

First I shot the 23 grain flat base, 1.5 inch group. All groups real 5 shot groups, not 2 or 3. Second I shot the 17.5 grain dish base, over 2 inch groups.

Next the 20.2 grain dish base and about 3/4 inch groups. The 24.8 dish base were slightly better. And the 27.5 grain were back to over an inch. I do not know the speed of any of the slugs, didn’t have my Chrony.

Am I done yet? Not by a long shot. The two best performers now need to be shot at various speeds from about 980 FPS down to 880 FPS in 20 FPS increments. Once I find the best of the two at the best speed, then it’s out to 100 yards for more testing. 
And of course I also need to try the FX Hybrids. The Eddy can be adjusted easily up to close to 1000 FPS, so I’m not limited there. 

Slugs aren’t like pellets where the gun shoots 18.1 grain JSB accurately and it’s been proven thousands of times for your specific gun. You COULD get lucky, but you could also win the Powerball.
Slugs take time, effort, lots of slugs and lots of air. But once you find the magic, you’re golden... I 

And if you just cranked the HST all the way in, you are way past the highest speed achievable with this reg setting. If you go in with the HST, the speed will increase for a while and then begin to decrease. Going in farther will just continue to decrease. So maybe you aren't seeing the max you could get. You may have gone past it.??? And compared to the other guys here with my little bit of tuning experience, I don't think ANY gun will work well with the HST set at coil bind.

Crusher