Proper tuning

[badimpact]

I’m trying to figure out proper tuning playing with slugs. I read slugs like higher reg pressure. We can shoot at 930 with reg at 100 or shoot same speed with reg at 130 or 150:. So what which way is better? Is one right and the other wrong? Are there guidelines depending on what caliber I’m shooting. I have done some testing with my 25 cal m3 and it doesn’t seem to affect pellets a whole lot but when trying to tune slugs for accuracy it has different effects. 

 

[KatoKevin454]

I think the best answer is to tune for smoothest air transfer and least air usage, with smooth air transfer you get excellent accuracy due to less recoil, I like to keep the regulator at the lower spectrum for smoother operation, too high of a regulator setting can cause valve lock and causes excessive wear on the valve poppet and springs, I always try to achieve the best accuracy with a good velocity at lower pressure settings, this will help your gun last longer and be more accurate.

 

[Long_Gun_Dallas]

Typically higher pressures are considered better. Higher pressure air speeds up the projectile earlier, quicker. It doesn't need as much volume as a lower pressure charge. What this results in is pressure that has dropped more at the exit of the barrel than a lower pressure charge of equivelant force. Often equating to less turbulence acting on the projectile. Also operating at higher pressure will result in quicker valve operation (typically) and this seems to aide harmonics as well? 

Of course there is a sweet spot, so just see what your gun likes. 

Lots of impact owners run relatively low pressure on their slug tunes, and still get great accuracy.

 

[biohazardman]

I was shooting mostly < MOA groups at 100 yards with my .25 700 Slug A liner a with a reg pressure of about 135bar.

 

[mtnGhost]

I have always had better results & efficiency with higher pressure.

 

[MikeVV]

Two to one...so far.

Higher pressure to lower pressure, one sorta mid-pressure.

Comeon all you experts, relate your say.



Mike

 

[Vetmx]

This just pertains to an Impact and one particular slug. Also this is for the most outstanding accuracy, not just good enough. I found a great tune that put my speed at 935fps. Shot the gun several months this way. Did some mods with opening up the porting and probe. Bumped the reg up and started my tune at a way higher velocity. After lots of shooting I finally found bliss. Headed downstairs to the chronograph to see what my new speed was going to be for me to enter into my calculator. Guess how fast the gun was shooting now? Yep, 935fps. Measured the valve and it was shut down more than before with my lower reg setting and no mods tune. The mistake I made with my first Impact and I see it all the time here is not committing to a projectile long term. I guess there are just too many gadgets, knobs, slugs and hearsay about what Billybobs magic tune is online for guys to stay focused. As far as speed goes I will leave you with this, from the time my reg was at 110b and all the way up to 135b, I can always find the most crazy accuracy I’ve ever seen out of an airgun at 100yrds when I shut the gun down to 825fps. My groups are so stupid at 100 that I won’t even post them here out of fear of being called a liar. I don’t leave the gun that slow because the trajectory is horrible. The gun is also so quiet that I don’t think I would even need a mod. What does that tell you? It’s about turbulence. But that, and a good seal is for another topic.

 

[Long_Gun_Dallas]

That sounds about like my 700mm .218 36gr slug experience with my Crown. About 865fps the groups were absurd... I didnt even bother properly measuring or documenting or sharing them. Trajectory was pretty bad, and the gun was super quiet, too. It was almost like the air expanded more... like the muzzle pressure was noticeably lower using heavier rounds? Like the additional resistance the heavy slugs provided gave the air more time to expand?

 

[Vetmx]

Depending on your standards, finding a good or decent slug tune is not necessarily rocket science. Understanding it is.

 

[badimpact]

Thanks guys for all the good input! Do you think that most any slug can be tuned to shoot accurately or what slug would you recommend? Would you recommend the superior heavy liner to other impact owners?

 

[Long_Gun_Dallas]

That's kinda of a cart before the horse scenario. Your barrel will determing the proper projectile, or your projectile will determine the barrel. Typically most people pick the projectile, then get the twist rate they need, and then size their projectile (diameter) appropriately.

I like using standard superior barrels because I dont shoot ultra heavy slugs. I've got like 7 different fx barrels alone, pellet, slug, ST, superior, I have no need or want for superior heavy

 

[badimpact]

Ok so I’ll ask you, what slug and setup did you find shot good for your rifle? I read the nsa 32gr seemed to work well for guys using the superior heavy liner.