FX Help tighten up SD/ES with Slugs

[ScopeFX]

Somewhat struggling getting the SD/ES to tighten up. Info below. My pellet M3 is in the single digits but this one is hovering a bit.

Impact M3 .25 700MM
Slug Liner/Tungsten Hammer
Reg 1: 190
Reg 2: 155
Macro: 15
Micro: 4

Max speed is about 1035 fps or so. I know people say to be 3-5% lower than max. I could cut a touch more speed to get it in the 980’s?

 

[bdzjlz]

What slug are you shooting?

 

[ScopeFX]

What slug are you shooting?

Those were NSA 38.5gr

 

[Dairyboy]

I'd say even higher honestly for a tighter spread. Some guns like to be closer to set point for better consistency. Doesn't hurt to try i guess maybe 1010avg??

 

[Vetmx]

If your slug diameter is too big, it can cause an ES issue.

 

[coastal drifter]

I use napier power pellet lube, I don

If your slug diameter is too big, it can cause an ES issue.

I use Napier power pellet lube on all my ammo, I dont know if that will help but I believe it keeps my barrels cleaner longer.

 

[coastal drifter]

I use the valve adjuster to tighten up the ES on my M3, small increments

 

[wooferocau]

What are groups like?

 

[Chukar60]

Try a lighter hammer weight. I am guessing the one from the FX slug power kit would prove a better match for you.

 

[shambozzie]

Look like you are speed shooting by time between shots. Regulator recovery time a possibility.

 

[HogKiller]

There is one other explanation, but only if your groups are less than ideal. If this is the case then too much air, if not the case then I'd lay it on the barrel/slug.

 

[LDP]

I know rifles vary but seems like you have quite a bit more hammer pre load than I do for basically the exact same setup. You dont list what your valve adjustment is set at but heres my settings.
First reg: 195 bar
Second reg: 150 bar
Macro: 6
Micro: 2.5
Valve travel adjustment: Approx. 1/4 in from fully open.

I topped out at 1045 fps with those regulator settings. I use young country lube 103 for my slugs. Its a lube used for black powder so I figured it would be perfect for slugs. So far its been great it smells good and no chemicals to worry about. The only problem its not made anymore but theres recipes for making basically the same thing at home. Google black powder lube and you will get a bunch of hits for forums with home recipes.

I noticed when tuning if I got the valve adjuster closed too much I had to use more hammer energy than ideal and I got a harsh shot cycle and inconsistency in groups and fps. Now I make sure the valve adjuster is open to the 4th line and another turn and a half when I start my slug tune. I would work towards 990 fps with the valve adjuster fully open. Once you hit roughly 990 fps you should be getting some decent consistent groups and speeds. If its not averaging .6 - 1.0 group sizes then drop the pre load a click or two on the macro and re check. Once I see groups that look like it wants to be a single hole I play with the micro a little to see if it tightens the group a little. Once I have the solid 4 shots and a flyer or consistent sized groups around .6 I start turning in my valve adjuster 1/4 turn at a time. I tuned both my impacts this way. I see the flyers pull in until its a tight little group and FPS is very stable and easily single digit numbers. I had one impact take a full turn or so in on the valve to get tight groups and the impact yesterday took 1/4 turn. I struggled getting good results in my impacts until I stuck the slug power kit in and used those reg settings and followed the steps in that order for the adjustments. Reading the groups was pretty easy with this method and told me what the rifle and slug wanted to get the groups tight. Kind of like load development with my firearms. You can tell when a load is about to tighten up and needs just a little longer or shorter coal or a small change in powder charge.

 

[CharlieNC]

Interesting

 

[Vetmx]

I use napier power pellet lube, I don

I use Napier power pellet lube on all my ammo, I dont know if that will help but I believe it keeps my barrels cleaner longer.

Keeping the bore as consistent as possible is the name of the game. One of the ways you’ll know if your lube isn’t right is if you have to shoot some shots through your gun before it starts grouping good again. This has happened with several lubes I’ve tested.