10 fps fluctuations could be the pellets. I'm not familiar with the Avenger platform, so my reply may not be the best but I'll try. Also, never had a regulated pcp, but one with a reg. is in route. Now that I have your confidence... Lol, take with a grain of salt.I'd return the Hammer strike (spring) setting to it's previous position. It may have been too soft of a strike for the regulator setting. Other than that, I can't be of further assistance on your gun. I'd imagine too high of a hammer spring setting may just waste air, too low would be inconsistent/low power. Alternatively you could drop the reg. pressure to match hammer strike pressure, but you would lose power (gain shot count). To use the least amount of pellets/slugs would be to use previously proven settings. Most of what I know on tuning pcp's is for non-regulated guns. Even what I know may be a bit off, but with tinkering I can get the results I want. Valve pressure (psi), hammer strike, transfer port restriction and projectile resistance (weight and bore fitment) all affect consistency and power. Unfortunately it may take a bit of testing to get desired results. The higher resistance of heavy pellets/slugs may need a slight increase of valve strike/dwell time compared to lighter pellets. Fine tune with regulator setting may be an option.Hopefully some one with more experience will give input.
Rick,I have only tried a couple types of H&N slugs and JSB Knockouts in my 25 Avenger but it doesn't like any of them. Does yours like the Hybrids? Also interested in how it likes the Nielsens. I've been thinking of trying some.Mine likes FX 25.4 and JSB Heavies (not MKII) the best of the pellets I've tried. I also have my regulator at 2200 psi at the moment. I shot it some at 2400 after starting at 1600 and stepping up from there. I got only about 10 fps more at 2400 than 2200 so I degassed and went back down a little. I haven't shot it much at 2200, I've been working on some new dining room chairs. Should finish them in the next couple days.I am far from an expert but my strategy on the Avenger has been to change the regulator to get the velocity where I want it with the hammer spring all the way out then try turning it in. At 2400 I got a little more velocity when I went one turn in but then when I went 1.5 turns in the velocity did not go up but the group size dropped significantly. When I turned it down to 2200, I did not back the hammer spring off I just tried it and it is shooting about the same 1/4 to 1/2 inch groups at 33 yards that it was at 2400. I was surprised that the hammer spring had that much effect on accuracy. I should probably try tweaking that further. I got about the same velocity with the knockouts at I did with the JSB heavies. So around 850 fps. If (or when) I try some Nielsens I will start at my pellet settings and probably just try messing with the hammer spring if the groups are too big. I may just try that on the knockouts first. The knockouts were not terrible, they might shoot OK with a little different hammer spring setting.
Just a general idea….no Avenger, but do have other regulated PCP’s.Just to be sure:Original was 25gr. @ 865fps (about 41.5 foot pounds)They you backed out the striker tension and ended up with 33gr. @ 765 (about 42.9 foot pounds). We don't like to think in foot pounds….have to run an equation…..we’d rather just think in velocity, but the two aren’t that far apart in terms of energy per shot.If the goal is to get the heavy weights up to about the same speed (but a lot higher energy), are going to need either more air released (striker striker hit), or a higher reg set pressure, or both.
Today I shot a group of fx hybrids. 25cal, using a wierd double tune I had. I'll explain. Originally it was set for fx 25gr at 865fps with many, many, duplicates all the way to reg setting at 2200psi.Well I ran out, I had some jsb 33gr so I ended up backing out the hammer spring to get the best group. Now I was seeing 765fps ish,? What I mean is,no more duplicates and at some point I think I noticed a 10fps drop at around 3000-3200psi. (Or +10fps at full psi) So now to get to the point, how should I go about tuning the nsa 38gr slugs for that same consistent fps, from max psi to reg psi. Using as little ammo as possible.?I'm tuning the Venturi Avenger 25cal.Thanks,
Quote from: DMR214 on June 14, 2021, 11:46:46 PMToday I shot a group of fx hybrids. 25cal, using a wierd double tune I had. I'll explain. Originally it was set for fx 25gr at 865fps with many, many, duplicates all the way to reg setting at 2200psi.Well I ran out, I had some jsb 33gr so I ended up backing out the hammer spring to get the best group. Now I was seeing 765fps ish,? What I mean is,no more duplicates and at some point I think I noticed a 10fps drop at around 3000-3200psi. (Or +10fps at full psi) So now to get to the point, how should I go about tuning the nsa 38gr slugs for that same consistent fps, from max psi to reg psi. Using as little ammo as possible.?I'm tuning the Venturi Avenger 25cal.Thanks,Kinda sounds like whoever tuned it last had it all balanced out just about right with that first projectile and weight (.25 FX Hybrids), depending of course on how many shots you got out of it and how many you wanted to get. Why not just restore all settings to how they were and get more .25 Hybrids?