For the purposes of this post....
- "Heavy hammer" = 545.3grain hammer that comes in GHOST HP.
- "Heavy hammer spring" = 0.052 wire hammer spring
- "light hammer" = 493.2grain (455.2grain hammer that is probably a sub 12 fpe UK hammer + my home brew 38 grain hammer weight)
- "light hammer spring" = 0.047 wire hammer spring that came in the .177 Ghost Carbine
I was really hoping to throw that heavy hammer and heavy hammer spring in the Ghost and be up in the high 900s with MRDs. As noted, the plan was also to do some 23-27grain slug testing while I was up there in energy output But that's not what happened. And I'm not too sure why.
The swap over was pretty uneventful. Simple enough to take out the lighter hammer and lighter hammer spring, and put in the heavier ones. Reg pressure still at about 140 bar. Hammer spring tension wheel at "MAX" (original design). First shot over the chrono was 900fps with MRDs. Next couple were also right there around 900fps. This is LESS than I was getting with the lighter hammer and spring. Scratch my head for a minute.....Maybe needs more reg pressure since I'm theoretically smacking the valve harder so, increased the reg pressure.....to no avail. I got as high as 165-170bar and fps went DOWN to 885fps. More head scratching. Dropped the reg pressure down to 120 bar, fps of 860 with MRDs. Highest energy output was with a reg pressure of 135-140 bar.
At this point, I've got a heavier hammer, with a stiffer hammer spring, and a longer stroke. All three of which should equate to hitting the valve harder, therefore producing more energy. But it was producing LESS energy. Thought maybe too long of a stroke? So threaded out the nose of the hammer, fps went down about 25fps. Maybe too much hammer spring? So swapped back to the light hammer spring but kept the heavy hammer in the gun. FPS with MRDs went down to 770fps. What the @&%#@ he77?!?!?!
Assessed the smoothness of the hammer traveling in it's little home and compared the two, they're both smooth as silk, so no apparent friction or roughness issues there.
At this point, I'm wondering if I've got a failing valve or something horrible. So I go back to the configuration that I shot the XFT match with in December. Put the light hammer + my weight and the light hammer spring back in the gun, essentially replicating my settings from before this recent heavy hammer/heavy hammer spring adventure. First MRD over the chrono with my previous settings was 940, right where it should be (had reg at about 137 at the last match and fps was 920-930. New reg of 140 bar so expected fps to be up just a bit from that) . Shot ten over the chrono and they were something like 932-940fps. MAX on the hammer wheel will take them back up to 965, all of that is just like it did before with similar settings.
So, I'm stumped. All of the above taught me that I don't understand that valve very well. It DEFINITELY functions differently than a typical valve in a PCP.
Texting with
@Arzrover after all this and his final suggestion was potentially sear drag with the new, heavy hammer, but by that point I was frustrated and discouraged and had concluded that I'm done futzing with chasing power or max output or slugs (at least for awhile). I know that the Ghost will shoot the MRDs REALLY well at these settings, and I'm leaving it here for now and just enjoying the gun, by gosh!
For as much as I find myself tinkering and "tuning" airguns, I despise it. I enjoy immensely the act of shooting but I've sold guns before that were "tinkerers delights." I was too often pulled into that never-ending nightmare of chasing improvements through tuning.
So, after the above head banging against the wall, I needed to have a good day, rekindling my good feelings towards the Ghost. And that I did!
Too windy for true accuracy testing (been gusting up to 30mph these last two days at my place) but I realized I hadn't ever shot a full string over the chrono to see how consistency is. For sure didn't want to just do that into a trap in the garage so I set up so that I could do it outside. Also got the crazy idea to try to hold on the same impact point at 75 yards (lasered out to 76) for the entire shot string and see what the wind and pellet quality and shooting through a whole "fill" would do to impact points.
This is the first fill.
(before commenting about the apparent inconsistency...queue up the Karen voice "that line is all jagged
" please note that I have the increments of the vertical axis to be only 5fps).
And I thought it'd be educational to repeat it with a different batch of MRDs, to see if wider spreads could correlate with what I've deemed the less accurate batch, from previous testing sessions.
Second fill (different batch of MRDS)
Couple conclusions from the above...
- The lowest shots from both strings were in the last couple shots. Which suggests that either the reg manometer is a few bar off, or more simply that the reg slightly misbehaves if shots are taken all the way down to set point. From now on will be stopping and refilling around 145 bar.
- Filling all the way to 250 bar, versus only 240, doesn't gain much in the way of shot count.
- The previously decided less accurate of the two batches DID produce a wider ES.
- One of the two batches actually shot slightly faster as well. No visually discernable difference in pellet shape, but perhaps an average head size difference from one batch to the other.
- I am well-pleased with the consistency.
- Will fill to 240 bar and shoot down to 142-145 bar from now on, planning on a solid 50 shots per fill at just the slightest smidge under 50 fpe each.
- That is from a 480 cc bottle. Do what most would and add a bigger bottle and of course shot count will increase. Personally, with lots of time with tube guns, I'm pretty dang happy with a 50/50 tune (50 shots of 50 fpe each, between needing to fill up the gun each time).
Here are the groups at 76 yards. Upper left is the 55 shot group. Lower right is the 63 shot group. No wind hold offs or timing between gusts, simply aiming for center of the crosshairs, which were mostly missing long before the last shot of each group. Circles are 1 and 3/8 inches across.
Finally, after all this I was verifying dope at 20-100 yards for Xtreme Field Target when a dove landed at a lasered 162 yards. Ho boy!!! Missed him the first shot but could see where it went. Dove moved a few feet but didn't fly off. Took a couple clicks off and NAILED that sucker on the second shot!!! He dropped like a rock and I sat there mouth-hanging-open SHOCKED. That is my new record long shot on a Euro dove. With the Ghost HP and 25.4grain Monster RDs. And from sticks and a stool!! Strelok told me 83 clicks initially and that's the first shot that went over him, and to the right from the wind. I took off 11 clicks, for 72 clicks, or 7.2mils of hold over and held into the wind about 1.5mils on the second shot. (scope is zeroed for 35-45 yards)
And THAT was just what I needed to get over my earlier "tuning" frustrations and fall back in love with the Ghost.
(For those of you who have been hanging around for slug testing, I apologize. I had every intention of doing it while I had the gun cranked up with the heavy hammer and heavy hammer spring but, those two things didn't crank the power up, as described above. Slug testing may eventually happen but it won't be any time soon. As good as this gun shoots with .22 MRDs, that's what I'm sticking with, at least with the high power side of the Ghost barrels currently in my possession. Also, as
@zx10wall pointed out, this slow twist poly barrel is not likely to produce the sort of accuracy most would like to see. And for that matter, my method of testing and reporting, where I actually show ALL the results, isn't going to do much for the slug lovers amongst us. Simply put, I've shot A LOT of .22 slugs at 45-60fpe, from a lot of different barrels and guns.....and they've never done better than what .22 Monster RDs can do. If there's any slug magic in airgunning, it ain't with .22 cal in the 45-60fpe realm).