Tuning Novice trying to tune .22 Dreamline Tac Compact bottle

[TN_Yankee]

So, I've had this gun for almost two months now, and have tried tuning it 3 times. I'm new to FX, and am slowly starting to get the hang of it. Ironically, the best tune I've had yet was the first one, though I'm sure it could have been improved as well. Since this has the 300mm barrel and small bottle, I'm looking to get a compromise on velocity vs. shot count, at around 800-810fps with JSB 15.89 to start with. Ideally, I'd then be able to dial the power wheel back & get good accuracy out of the CPHP, for cheaper plinking as well.

So, I have a few questions from my tuning session the other day. This was a combination of ~15-year old and new JSB 15.89, straight from the tin, with a few really dented pellets pulled out.

1) Early on, I had reached a velocity plateau at a particular regulator pressure & HS tension. I then turned up the reg a bit, and the velocity dropped. I believe this was because the HS was now too weak, and out of balance with the pressure the valve was seeing. Is this correct? And, is this what's termed "valve lock?" I then turned up the HS tension, and the velocity went up, but I want to make sure some other condition wasn't at play here (trying to understand the fundamentals).

2) Eventually, I got to about 840fps (TP medium, PW max, reg 140-145). Dropping the PW to 5 gave me 809fps, right where I wanted. I then refilled the bottle to 245bar, and immediately the velocity dropped to the +/- 780fps range, and stayed there until I reached the regulator set point. Why did it drop? I can see if this was another case of valve lock, but the velocity should have come back up as the reg pressure dropped, but it never did.

3) I've posted my string below, and while the regulated shot count was OK (ignoring the lower-than-desired velocity for the moment), the extreme spread is pretty bad. I know the gun can do better, as my original tune was less than 4% across 70 shots. Is this erratic behavior another example of partial valve lock, and if so, would slightly increasing the HS tension improve it?

I kept shooting for a while after it dropped off the regulator, just to see the gun's behavior.

Many thanks in advance for any advice.

Mike

 

[Vetmx]

First, you need your TP wheel set to whatever is wide open now. On my gun it’s .22/.25. They changed what they write on the wheel now but having yours set on medium is choking the gun and that’s a no no for your 15.89 pellets. You might need the medium setting when you switch to the 14.3’s after your base tune is set for the 15.89’s. Second, are you using the HS wheel to find your max speed for the reg setting or the little hex screw by the wheel?

 

[TN_Yankee]

I had the TP set at medium, as I had gotten the impression from other posts that unless using heavier pellets or slugs, the high position was wasting air. But, maybe with the short barrel, it needs to be on high. I have frequently seen high give a lower velocity than the medium setting, for a given HS tension. Is that due to the tension being too low?

FWIW, this gun is stock, with no modified port sizes, etc.

I use the the hex screw, with the PW at max.

Thanks for the quick reply!

 

[Vetmx]

You will never waste air if your reg setting and hammer spring tension are in balance. With regulated guns, max porting is what you want. 

 

[Vetmx]

The TP wheel is just a crutch. A quick way to slow the pellet down if you want to shoot something lighter. If you switched to a .177 barrel, then it might be a good idea to start on medium. I made a slightly longer barrel for my Compact but my base tune for 18gr pellets went like this. Reg just under 150b, HS wheel set on #5, used the hex screw to find my max speed of 941fps. Confirmed max speed when I turned my wheel to Max and speed dropped to 931fps. Now I turned wheel to #4 932fps, #3 923fps then #2 was 897fps so that’s where I left it. When I drop to 14.3’s I move my TP wheel to .177/.22, which is your medium and I put my HS wheel on #1. They shoot great. The wheels let you do this but you have to understand that this is not the optimal tune for the 14.3’s. But it works good enough when hopping around with different weight pellets.

 

[Jlowe]

Check this YouTube video out on tuning your gun. If I were you I would add a Power plenum. It's a very easy way to gain power. 

https://www.youtube.com/watch?v=8PjT5tEa7-8

 

[TN_Yankee]

Thanks for the link, Jason. I had watched again just recently. What I'm after is not so much "how" to tune, but "why" I'm seeing certain things. Once I can get a bit of the workings figured out, I hope to be able to tune it properly, and not just twiddle a couple of knobs.

The power plenum is a good idea, but FX beat you to it by making it standard on this gun these days.

I appreciate your input - thanks!

 

[Vetmx]

The thing that strikes me as odd with what you wrote is going from max 840fps to #5 809fps is just too big of a decrease. Maybe it’s because you’re choking the gun off with that medium TP wheel setting, maybe not. But you still need to set your TP wheel for max flow. Your gun going from 809fps to 790 is not that shocking. That might just be where the spring finally settled after the adjustment. It happens with almost all airguns. Looking at my notes from when I had the shorter stock barrel on it is kinda confusing. I was experimenting with a dual TP and also extra plenum. What I can tell you is a 145-150b reg setting should easily get you 880+fps. Then you can click the HS wheel down to the 830fps range and see what your shot string looks like. A super short barrel seems to like a high reg setting and a quick shot of high pressure air. You can’t control your dwell time with a valve knob, so you have to do it with a higher reg setting and just the right hammer strike. 

 

[qball]

Your reg is way too high. Set your reg to 110-120bars and go from there. 

 

[Vetmx]

Your reg is way too high. Set your reg to 110-120bars and go from there.

Was hoping you would chime in. My Gen 1 compact with the extra plenum and oval port wouldn’t push a 15 very fast until I got to 140b+. Did they lighten the hammer or something with the newer versions? When they added the plenum I wonder what else they changed. If he resets his reg to 120b, I hope he posts his max speed at that setting. My gun came set at 140b from the factory pushing 15’s 850’s max.

 

[Jlowe]

Your reg is way too high. Set your reg to 110-120bars and go from there.

I was getting ready to say the same thing. The hammer spring and weight are not the same as the 25cal is and they don't seem to do well with the higher reg settings. 

 

[Vetmx]

Your reg is way too high. Set your reg to 110-120bars and go from there.

I was getting ready to say the same thing. The hammer spring and weight are not the same as the 25cal is and they don't seem to do well with the higher reg settings.

That would definitely explain this….

 

[TN_Yankee]

If he resets his reg to 120b, I hope he posts his max speed at that setting.

Looking back over my notes, I did shoot some at that pressure, but it isn't clear what the results were, so I'll do as @qball suggests next time. Before & after I received this gun, I think I watched several videos and read about every post on the internet about tuning & settings for it, which has likely led to some of my confusion. I fully understand & support FX's "continuous improvement" process, but it does make comparing newer to older guns much more confusing when it isn't clear what production changes have been made.

I post again when I've done some more shooting. We have strong storms and plenty of rain predicted through the weekend, so I may not be able to get outside.

 

[qball]

Your reg is way too high. Set your reg to 110-120bars and go from there.

Was hoping you would chime in. My Gen 1 compact with the extra plenum and oval port wouldn’t push a 15 very fast until I got to 140b+. Did they lighten the hammer or something with the newer versions? When they added the plenum I wonder what else they changed. If he resets his reg to 120b, I hope he posts his max speed at that setting. My gun came set at 140b from the factory pushing 15’s 850’s max.

Like @jasmlowe said there are 3 hammer weight sizes. All 177 and 22 comes with 7 gram hammer, .25 comes with 11g gram and 30 comes with 13 gram hammer. Or light, medium and heavy hammer for 22, 25 and 30 respectively. Light or 7 gram hammer max out right around 115-120 bars, medium or 11 gram hammer max out around 145-150 bars and 14 gram or heavy hammer max out at 170 bars which is the max pressure the amp regulator is rated for but I don’t know anyone go pass 160 bars. 



the part a lot of people make mistakes on is thinking the short 300mm barrels can achieve the same speed as 500mm barrels. The 300mm barrel is best @760fps or lower, it can go as high as 800FPS but accuracy won’t be consistent with a lot of flyers because the gun is over powering the barrel. It can be argued that the shorter the barrel is the harder to tune at the barrel’s max speed. It’s a compact and let it be a compact, stick to 760fps or lower then tuning is easy. Set your reg to 110-120, TP at medium or middle then dial your HS to 750-760fps and done. Depends on the ammo you can go as low as 80 bars to get more shots if shooting really light ammo, as long as you stay under 760fps the gun will be very accurate efficient and quiet. Trying to any higher is not really productive…….ask me how I know! LOL 



btw the .25 compact max sweet spot is around 800FPS because the barrel is longer at 380mm instead of 300mm in 177/22. 

 

[TN_Yankee]

Thanks for the clarification. I've looked at the drawings several times, and they don't spell any of this out (unless there's another FX document I haven't seen). Where can I find part numbers? I likely would only switch if I went with another caliber, or experimented with a longer barrel & slugs, but it's nice to have the info on hand.

1) Is there a downside to running a medium/11g hammer with .22?

2) I've read repeatedly that the JSB 15 & 18 like to run in the 860-880fps range, hence my desire to try to get as close as I can to that. Do they still perform well at +/-760, or are you now using a different pellet?

 

[TN_Yankee]

I will point out that I have had the gun up to 860+ fps with the 15s in the past, though I don't have any chrono data to examine. From what you guys are telling me, the gun will be pretty "high strung" at that point, and accuracy will likely suffer.

 

[Vetmx]

Something wasn’t jiving so I had to do some research. My gun wasn’t a bottle gun, they didn’t have them then so we made them bottle guns. My original barrel was 12.5” long. The new bottle guns like yours come with a 11.8” barrel. It doesn’t sound like much but that’s why I had no problems shooting 15’s 860fps. At that time I actually shot 18’s at 835fps for quite a while. You mentioned longer barrels. That’s why I made a 14.75” liner and barrel for my gun. With my 18.1gr pellets shooting 835fps, by simply going from my 12.5” barrel to my 14.75” barrel, my gun went to 923fps. I still have my reg at 140b but now instead of being on #3, I’m on #2 on the wheel for 897fps. My max speed at that reg setting with 18’s is 941fps. Just figured I would give you some data in case you find your guns happy spot but are not thrilled about anemic velocities. Here’s a pic of my gun with the longer barrel and shroud I made. It’s a little bigger than it was but by no means a big gun.

 

[TN_Yankee]

Interesting - thanks for the details. From my day 1 notes on this gun, with maximum hammer spring tension, PW on Max, TP on high and 150bar reg, I got 830fps with JSB 18gr, and 823fps with AA 18gr. I got 870fps with JSB 15.89, and 899fps with CPHP, on the same settings. So, I was able to get close to your original numbers, though it took a higher reg pressure to do it (both my bottle & reg gauges seem to read about 5 bar low, as compared to the 2" Wika gauge on my SCBA fittings). But, I knew running everything wide open was likely not where the gun & I wanted to be.

 

[Vetmx]

I’ve seen qballs posts in other topics related to the DL Compacts. He is very consistent recommending the 760fps range. I agree 100% that you can only push a gun so much and believe he found the sweet spot for the gun. If I turned my original barreled gun down to 800fps, I’m sure the gun would have been even nicer. I had it tuned right on the ragged edge of where I’m comfortable. But eventually I came to the realization that 2 inches of barrel length was going to put me right in the trajectories that I’m used to. And the gun would do it in its sleep. If I had a 300mm Compact and didn’t have the means to build barrels, I would focus on the 14.3gr pellet and try everything to get it to shoot well at a respectable velocity. 

 

[qball]

Thanks for the clarification. I've looked at the drawings several times, and they don't spell any of this out (unless there's another FX document I haven't seen). Where can I find part numbers? I likely would only switch if I went with another caliber, or experimented with a longer barrel & slugs, but it's nice to have the info on hand.

1) Is there a downside to running a medium/11g hammer with .22?

2) I've read repeatedly that the JSB 15 & 18 like to run in the 860-880fps range, hence my desire to try to get as close as I can to that. Do they still perform well at +/-760, or are you now using a different pellet?

just call FX and ask for the medium and heavy hammer, they are the same for DL, wildcat and maverick and about 6 dollars each plus shipping so very inexpensive. the only down side to running heavier hammer is you can’t turn the power down as easy if you want to but most people don’t like to turn down the power like I do or use much lighter ammo. If you stick with 18 grain the medium hammer will work well. 


It is true that most pellets shoots best right around 830-860fps however that does NOT mean they shoot bad at slower, far from it. Some pellets are designed to shoot lower like wade cutters are designed for right at 500fps. I have no problem putting pellets on top of each other if condition permits shooting only 600fps in my DTC, my challenger will do that all day at 500fps if wind allows with the same pellets, same goes to my 1701P at 450fps with the same pellets. 


can you get the compact to shoot faster, of course but I specifically said max sweet spot not max speed. With lighter ammo and 150 bar reg with medium hammer you can get well pass 800fps even with 300mm barrel but very hard to tune thanks to the short “runway” resulting in a lot of muzzle blast which not only waste air but also very loud AND without a good air stripper setup properly muzzle turbulence which will create a lot of flyers or shot gun pattern groups. Fortunately most donnyfl caliber specific moderator can help(not fix) with that issues.


let’s be honest, 40-50 FPS at 30-50 yards won’t make that big of difference but it will get you much smoother gun, double the shot count and very consistent accuracy. I’ve pushed my 2 DTC as far as it can/will go and it’s not worth it IMHO. You can hear the muzzle report change as soon as you shoot pass 760fps. Once you get hang of tuning then you definitely can try to go faster but be prepared for frustration as pushing anything at its limit will be. I even shot slugs out of my DTC in 177 and 22 caliber and as long as it is under 760fps the slugs shot great even out to 100 yards, higher speed absolutely does NOT equate to better accuracy, far from it.