First off, let me say that if you buy the FX DRS Tactical, and in my case, the 500mm .22, it's probably best to just leave it at the factory settings if you are OK with the performance. I'm not saying don't muck with it, but mine was tuned pretty well for 16gr pellets at just over 900 fps from the factory.
Background - my gun with factory settings (for the last 1000 or so rounds) was shooting 16gr FX pellets (and a few others) at 910 for just about 65 shots. That's pretty darn good. Fill to 230 shoot down to around 85-90. I believe that my reg was set around 85-90, so when shooting, a lot of times I would stop shooting at 100b. Still got 60 shots. I shot a variety of ammo and everything from HN 21gr slugs to 16gr pellets shot around 29-30 ft.lbs and very good accuracy. Needed a moderator obviously, not a quiet gun, but I knew that so I put on a 4" Huggett Atom and put a sleeve on it to match the barrel OD. All good, but not Taipan quiet.
Now for the update. I decided I wanted a gauge on the plenum. Ordered the gauge and couldn't get it to seal (posted that in another thread). Said heck with it, ordered a SHP and angle bracket. $125, I've spent more money or worse things so I figured I'd give it a shot and see if there are any gains, plus, I get to see my reg pressure.
Degassed gun, removed old plenum, installed new SHP and angle bracket, installed new FX mini gauge and air'd back up. Yup, the reg pressure was right around 85, so it was probably around 90 before. I left well enough alone and started shooting. I wanted to shoot 18gr pellets at 880-890, so this is where I started to muck with factory settings.
New SHP and reg at 85 bar 0 clicks on HS
16gr 915 fps
18gr 865 fps
fps seems more erratic than factory settings, didn't really gain anything and I didn't expect to.
SHP and reg at 100 bar 0 clicks on HS
16gr 860-900 fps
18gr 800-830 fps
fps all over the place - the shot pitch sound was low, then medium, then low...
SHP and reg set at 100 bar +5 clicks on HS
16gr 900 fps
18gr 850-880 fps
fps spread better but still not great
SHP and reg set at 100 bar +10 clicks on HS
16gr 940 fps
18gr 900 fps
now this seems better, seems more stable but also a change in shot pitch - a little louder but stayed the same tone
backed it off -1 click, so now I'm at +9 from factory settings and 100 bar and SHP
18gr 900fps
21gr HN slugs 855 fps
ran a full shot string and got right at 60 shots for 32-33 ft.lbs depending on pellet/slug.
I'm gonna stay at these settings for a while and let it settle. I think that using the SHP, it likes more hammer, probably because of the larger volume of plenum air. It's really not much different from factory settings (around 30 fps), and I found that the factory settings shot a little quieter and the spread was better. Time will tell I guess. If I did it all over again, I would just buy the 600mm and have a reg gauge installed from whomever I buy it from. I think that a short barrel, large plenum and relatively low reg pressure requires more HS to get it to shoot good.
There's not much tuning info out there on the DRS Tactical, but there's enough to get started.
A few pics of the SHP, gauge, and Huggett.
Background - my gun with factory settings (for the last 1000 or so rounds) was shooting 16gr FX pellets (and a few others) at 910 for just about 65 shots. That's pretty darn good. Fill to 230 shoot down to around 85-90. I believe that my reg was set around 85-90, so when shooting, a lot of times I would stop shooting at 100b. Still got 60 shots. I shot a variety of ammo and everything from HN 21gr slugs to 16gr pellets shot around 29-30 ft.lbs and very good accuracy. Needed a moderator obviously, not a quiet gun, but I knew that so I put on a 4" Huggett Atom and put a sleeve on it to match the barrel OD. All good, but not Taipan quiet.
Now for the update. I decided I wanted a gauge on the plenum. Ordered the gauge and couldn't get it to seal (posted that in another thread). Said heck with it, ordered a SHP and angle bracket. $125, I've spent more money or worse things so I figured I'd give it a shot and see if there are any gains, plus, I get to see my reg pressure.
Degassed gun, removed old plenum, installed new SHP and angle bracket, installed new FX mini gauge and air'd back up. Yup, the reg pressure was right around 85, so it was probably around 90 before. I left well enough alone and started shooting. I wanted to shoot 18gr pellets at 880-890, so this is where I started to muck with factory settings.
New SHP and reg at 85 bar 0 clicks on HS
16gr 915 fps
18gr 865 fps
fps seems more erratic than factory settings, didn't really gain anything and I didn't expect to.
SHP and reg at 100 bar 0 clicks on HS
16gr 860-900 fps
18gr 800-830 fps
fps all over the place - the shot pitch sound was low, then medium, then low...
SHP and reg set at 100 bar +5 clicks on HS
16gr 900 fps
18gr 850-880 fps
fps spread better but still not great
SHP and reg set at 100 bar +10 clicks on HS
16gr 940 fps
18gr 900 fps
now this seems better, seems more stable but also a change in shot pitch - a little louder but stayed the same tone
backed it off -1 click, so now I'm at +9 from factory settings and 100 bar and SHP
18gr 900fps
21gr HN slugs 855 fps
ran a full shot string and got right at 60 shots for 32-33 ft.lbs depending on pellet/slug.
I'm gonna stay at these settings for a while and let it settle. I think that using the SHP, it likes more hammer, probably because of the larger volume of plenum air. It's really not much different from factory settings (around 30 fps), and I found that the factory settings shot a little quieter and the spread was better. Time will tell I guess. If I did it all over again, I would just buy the 600mm and have a reg gauge installed from whomever I buy it from. I think that a short barrel, large plenum and relatively low reg pressure requires more HS to get it to shoot good.
There's not much tuning info out there on the DRS Tactical, but there's enough to get started.
A few pics of the SHP, gauge, and Huggett.
