Air Venturi Avenge-X/PCP newbie concerns

[basketbob]

Have you tried running a heavier pellet? JSB makes an 'Exact Monster Diabolo @ 13.64 gr and may help to lower the velocity of your current tune to speeds more to your liking. There are also slugs. . . .

I have an unopened tin of those 13.43gr pellet but haven't tried them yet, figured the 10.34gr was the optimal weight. I will definitely try them out. I'm also not beholden to getting the velocity below 900 fps but I've heard that anything above 900 results in inaccuracy so was just trying to play it safe.

 

[basketbob]

I wouldnt go lower than 1500psi on the Reg anyway. Too low or too high will increase wear and shorten the service life of the Reg/seals. I havent tried out the new AvengX but the old version Avenger we had a problem with the 177 version shooting waaaaay too fast no matter the settings. Some pcp's are just too powerful and dont have a low enough range of adjustment to get the tiny pellets going slow enough. I would try raising the Reg to say 1600psi or 1700psi with the hammer spring all the way backed out. If you leave the hammer spring adjustment at its lowest setting, and slowly raise the Reg pressure you should see the other side of the bell curve and velocity go down. If it doesnt, then your only other options would be to use the power port adjustment, or try heavier ammo.

Sounds good. At least I have a few options to try! I have an unopened tin of 13.64gr so it's about time to bust those open.

 

[Vetmx]

My Edgun Lelya .177 is accurate way north of 900fps so it won’t hurt to try. I’m curious what your peek speed is at 1500psi. How much faster will your gun shoot when you start adding spring tension at 1500psi?

 

[basketbob]

My Edgun Lelya .177 is accurate way north of 900fps so it won’t hurt to try. I’m curious what your peek speed is at 1500psi. How much faster will your gun shoot when you start adding spring tension at 1500psi?

I just tested that out and it didn’t seem like the velocity really changed. However, I also tried shooting the 13.43 monsters at 1500 psi and it jumped down to 830. These might be the way to go for this gun

 

[Vetmx]

I just tested that out and it didn’t seem like the velocity really changed. However, I also tried shooting the 13.43 monsters at 1500 psi and it jumped down to 830. These might be the way to go for this gun

Well that’s a good thing and a bummer. Your gun has just a little too much spring. Not way too much spring. So close and yet so far away.

 

[basketbob]

Well gentlemen, I think I just completed my first successful tune. 1800psi reg, 177 13.43gr, ~863 fps. Max velocity at that reg was around 900 so using the 5-7% rule I aimed for 864. This is pretty fun! Now to see how it groups because I did this tuning indoors shooting 2 feet away at ballistics gel (thank god tomorrow is Friday).

p.s. - does anybody know how to get the damn FX pocket chronograph to not miss shots??

 

[CarlV]

Just a shot on the dark here. Have you verified you have 6 turns of hammer spring adjustment? Some had a rough spot about half way. You may be using more hs than you think

 

[JimD]

No experience with the FX chronograph but the $20 alibaba ones almost never miss shots. Congratulations on your successful tune.

I've been messing with tunes of my 177 caliber P35. Very different gun. It's hammer spring was too much so it got shortened. But it doesn't like the velocity to go even 5% below the peak. I shot 2 5 shot groups as I gradually backed off on the hammer spring. My peak on H&N Baracuda Match 10.6s was about 900 fps (reg is about 130 bar (no gauge) which is about 1900 psi). Barrel is only 450mm. I am not sure yet where the best accuracy is but 850 fps (6% below) was too much - groups opened up noticably. Groups from 865 fps to 885 fps are pretty similar. I need to investigate further. But the whole point of this comment is I think it is worthwhile checking accuracy before deciding on how much under peak velocity you want to use. You may find going a little outside the "5-7%" shoots better. It is still efficient with this sort of tune.