TL;DR: Same liner/probe from an insanely accurate MkII moved over to an M3 at same fps settings won't consistently group like before...why?
Last fall, I picked up two Impact MkII's (a 0.25 500mm w/ Superior liner and a 0.22 600mm w/ Slug liner & Huma high flow transfer port and probe). I set the 0.25 Compact to shoot 25.4g JSB's at 860-870fps and the 0.22 slugger shooting 24.8g 218 NSA slugs at 900fps and those two rifles proved to be two of the most accurate and consistent rifles I'd ever owned. I could pick up either one and could easily & consistently shoot ragged one hole 5-shot groups at my 40yd backstop almost every time. The 0.22 was slightly more consistent than the 0.25 and was producing some of the most ridiculously small groups I've every shot.
Then the M3 came out and I couldn't resist so I picked up a 0.25 500mm and 0.22 600mm M3 to replace the MkII's. A quick tune on the 0.25 M3 to match the same settings above and it quickly proved that it is just about as accurate as its MkII brother (which was then sold). The 0.22 M3 hasn't been as cooperative.
The 0.22 M3 came with a Superior liner, which I swapped out for the Slug liner from the MkII. I also moved the Huma probe over to the M3 and rotated the M3 barrel to used the larger "slug" transfer port. I set it up to shoot around the NSA's at the same 900fps (1st reg = 150bar, 2nd reg = 110bar, 8 on power wheel, 3.5 on quick tuner and valve at ~4 bars) and the first few groups were adequate. But I quickly noticed that the M3 0.22 wasn't anywhere near as consistent as my MkII was - I'd get 2 or 3 fliers in each 5 shot group. From one target to the next, POI would move around unexpectedly. Checking on the chrony it shows a spread of about 10-12fps - not great but horrific. If I really work hard, I would only get a 1 hole groups about 10-20% of the time (whereas the MkII with the same liner would do it 80-90% of the time).
I thought maybe I didn't do a good job installing the slug liner so I double and triple checked the o-rings, barrel inlet, liner lock, etc. and the results were the same. I tried cleaning the barrel - nothing changed. Then I tried indexing the barrel - which helped a little bit but it's still nowhere near as accurate or consistent as the 0.25 is right now. It's super puzzling how the same exact liner/probe from the MkII installed in an M3 set to shoot at the same fps can have such different (and worse) results.
This 0.22 has been like this for the 2-3 months I've had it. So today, I thought maybe the NSA slugs might do better at a higher velocity so I turned the 2nd reg up to 130bar, power wheel to 10, quick tuner to ~4 and valve still at ~4 bars) to bring fps on the NSA slugs to 930fps . . . and got more or less the same results as before. I've never really been one to really tweak with my rifles that much so I'm running out of patience with this M3 - can one of you Impact gurus give me some advice as to what's going on here and how I can get this thing shooting like I know it can/should?
Attached below is the last set of groups I shot tonight. On the left are the typical groups I'm seeing with the 0.22 (I took my time with these groups and tried my best to get them to group (each bullseye is just over 0.5" wide)). On the right, I pulled out the 0.25 as sunlight was running out to quickly shoot some groups for comparison (the first group on top was very rushed and has two fliers but the remaining three, while still rushed a bit, are much more typical of the results I'm used to seeing). You can see how even rushed groups with the 0.25 are way tighter than deliberate groups on the 0.22. Both rifles shot off of a very steady tripod/ballhead combo connected to an ARCA extended rail. WTF is going on here???
Last fall, I picked up two Impact MkII's (a 0.25 500mm w/ Superior liner and a 0.22 600mm w/ Slug liner & Huma high flow transfer port and probe). I set the 0.25 Compact to shoot 25.4g JSB's at 860-870fps and the 0.22 slugger shooting 24.8g 218 NSA slugs at 900fps and those two rifles proved to be two of the most accurate and consistent rifles I'd ever owned. I could pick up either one and could easily & consistently shoot ragged one hole 5-shot groups at my 40yd backstop almost every time. The 0.22 was slightly more consistent than the 0.25 and was producing some of the most ridiculously small groups I've every shot.
Then the M3 came out and I couldn't resist so I picked up a 0.25 500mm and 0.22 600mm M3 to replace the MkII's. A quick tune on the 0.25 M3 to match the same settings above and it quickly proved that it is just about as accurate as its MkII brother (which was then sold). The 0.22 M3 hasn't been as cooperative.
The 0.22 M3 came with a Superior liner, which I swapped out for the Slug liner from the MkII. I also moved the Huma probe over to the M3 and rotated the M3 barrel to used the larger "slug" transfer port. I set it up to shoot around the NSA's at the same 900fps (1st reg = 150bar, 2nd reg = 110bar, 8 on power wheel, 3.5 on quick tuner and valve at ~4 bars) and the first few groups were adequate. But I quickly noticed that the M3 0.22 wasn't anywhere near as consistent as my MkII was - I'd get 2 or 3 fliers in each 5 shot group. From one target to the next, POI would move around unexpectedly. Checking on the chrony it shows a spread of about 10-12fps - not great but horrific. If I really work hard, I would only get a 1 hole groups about 10-20% of the time (whereas the MkII with the same liner would do it 80-90% of the time).
I thought maybe I didn't do a good job installing the slug liner so I double and triple checked the o-rings, barrel inlet, liner lock, etc. and the results were the same. I tried cleaning the barrel - nothing changed. Then I tried indexing the barrel - which helped a little bit but it's still nowhere near as accurate or consistent as the 0.25 is right now. It's super puzzling how the same exact liner/probe from the MkII installed in an M3 set to shoot at the same fps can have such different (and worse) results.
This 0.22 has been like this for the 2-3 months I've had it. So today, I thought maybe the NSA slugs might do better at a higher velocity so I turned the 2nd reg up to 130bar, power wheel to 10, quick tuner to ~4 and valve still at ~4 bars) to bring fps on the NSA slugs to 930fps . . . and got more or less the same results as before. I've never really been one to really tweak with my rifles that much so I'm running out of patience with this M3 - can one of you Impact gurus give me some advice as to what's going on here and how I can get this thing shooting like I know it can/should?
Attached below is the last set of groups I shot tonight. On the left are the typical groups I'm seeing with the 0.22 (I took my time with these groups and tried my best to get them to group (each bullseye is just over 0.5" wide)). On the right, I pulled out the 0.25 as sunlight was running out to quickly shoot some groups for comparison (the first group on top was very rushed and has two fliers but the remaining three, while still rushed a bit, are much more typical of the results I'm used to seeing). You can see how even rushed groups with the 0.25 are way tighter than deliberate groups on the 0.22. Both rifles shot off of a very steady tripod/ballhead combo connected to an ARCA extended rail. WTF is going on here???
