FX Fx impact m4 macro does not reduce speed much with 8.5g hammer? Is this normal ?

[Irish shooter]

On a previous post I noted I upgraded my hammer to 8.5g humma air hammer.

My reg was at 135 and and was achieving 950fps with zans 37gr. This worked fine for speed but accuracy was just ok.so I looked for a better tune. After some correspondence from zan they said I should be shooting them at 985-1010. So I upped my reg up get to these speeds.

However in both my tunes I found the tune ability with the macro was negligible. For example tonight when my reg was back to 135 I was getting 965fps with my macro on 16. I turned the macro gradually to 4 and there was only 3fps decrease.( I’m confused)

The only way I could get any noticeable drop or increase in speed was using my valve adjustment but that’s not the way to tune according to countless videos on YouTube that iv watched

I presume im doing something wrong if my macros isn’t having much of an effect.

Is my hammer too heavy ? Should I use 7.5g or revert back to 6.5g

Any advice ?

 

[airman_o]

you hammer the valve probably too hard with the heavier hammer. Probably you also installed the stronger spring? I'd try getting back to the original spring to restore your tunability.

 

[Irish shooter]

you hammer the valve probably too hard with the heavier hammer. Probably you also installed the stronger spring? I'd try getting back to the original spring to restore your tunability.

Yes I also changed the spring. But if I didn’t change these I wouldn’t be able to achieve speeds over 935fps for the slugs ?

 

[airman_o]

The only way is to try it. You could also try the lighter hammer with the stronger spring. I'd recommend to try the combinations to see what best fits you.

 

[greenbeans]

Yes I also changed the spring. But if I didn’t change these I wouldn’t be able to achieve speeds over 935fps for the slugs ?

Airman is spot on. At 135bar you’re most likely not going to be valve locked with a heavier hammer. For reference, I am running stock hammer and spring with reg at 131bar. Have to almost max out micro to reach Plato but not on 5 yet. On the knee at around 96.5% with micro a little below 4.5. Your setup right now is probably more suited for 150bar and beyond reg pressure.