.30 Impact, turned reg down, speed and accuracy went up. Huh?

[MonsterMaxx]

I love my Impact, but of late it's gotten a lot of tune improvements (1000fps stuff), but the accuracy has not been there. I attributed this to too high a velocity on the JSB 44.75gr pellet. 



Today a friend of mine came over and we did some shooting so I figured perfect time to try some stuff on the Impact and see if I could improve the accuracy, by that I mean at targets beyond 50yds.

So I started by turning the reg down a little, like one clock of the allen wrench.

Reg went down to 145bar just like it should have. Set on Min power, speed went up. huh? In the 900s

Again, 1 clock, 130bar, again, on min power speed goes up.

After two more adjustments I'm at 110bar on the reg and flinging led at 880fps, with groupes like this at 85 yards

Can't say I understand it, but I like it!

 

[Fire_at_will]

Harmonics is interesting stuff.

I had a 25 cal and 30 cal that both shot best at 110 bar. Not as efficient with the air tho.

 

[sonny]

whats the shot count with the lower reg? Did it go up or down .

 

[BigTinBoat]

If the speed went up when regulator was turned down it means you were tuned below the plateau originally.

 

[Eddie_E]

The velocity increase is easy. Your hammer and hammer spring are better suited for the lower pressure, much like the un-regulated guns being topped to max pressure.

The better accuracy could be anything from the air stripper peeling off the pressure wave better to barrel harmonics. If you put down more details like barrel length and exactly which variant of that gun, one of the pro-tuners, like Motorhead, will know for sure.

 

[Powerbroker]

I notice this effect too. The “plateau” is the correct term as suggested by BTB. Bob and Heavy and Ernest suggested a balance between the pressure and spring tensions. The spring might not be enough to push the valve due to high pressure.

 

[bubblerboy64]

I am surprised that you are getting 880 at 110 bar. 

Of course those gauges may not be actual values. 

 

[Jlacouturec]

its because now the valve is opening more, you have to achieve a balance between reg pressure and hammer spring tension!!

 

[cowabunka]

judging from the comments here, it would appear that with hammer spring tension at max, there can be no harm?

Or am I missing something?

 

[MonsterMaxx]

The gun is the model just prior to the X coming out, whatever that is. ST?

It's a 600mm barrel and I used both the FX silencer and the Neil Clague.

Ernest power tuned it, but it failed (main valve) pretty quickly. While it was getting fixed for that it got the MkII upgrades.

It's got the extra plenum.

The gauges are wika and were validated by Ernest prior to install.



I had the hammer spring all over trying different stuff, but mostly since I was trying for lower velocity it was on MIN. Yea, I"m at 880fps on 110bar w/ the MIN power setting. LOL



I forget, what's the other valve do, up by the bottle connection?

 

[jps2486]

I experienced the same thing. At 145 bar reg pressure, I had turned in the hammer buffer down to three lines. I only got 35 shots per fill with 880 fps. I started lowering the reg pressure and noticed the velocity increasing, then started to decrease when I approached 120 bar. I backed out the buffer till the velocity went back up to 880. Then, I was getting 40 shots per fill. Interesting. This is a delicate balance. BTW, my gun is a MK2.