Edgun R3 .22: Shot String, Air Efficiency, & Trigger
This will be a long post, sorry about that. Ran into the dive shop to fill up the scuba tank yesterday. The shop owner put on a pressure gauge to show me how much the tank was filled, because I was “hinting” at him that I could only fill the gun to 180 bars (~2610 psi) last time with a full tank. The tank was indeed filled to the maximum pressure around 3100 psi in this new fill. Interestingly, again, I only could fill the gun up to ~180 bars based on the gun gauge; but the gauge in the fill adaptor showed 3050 psi (~210 bars). It seems that the pressure of my Edgun was somewhat under measured by 440 psi or 30 bars. 🙄
I tested a shot-string using Combro Chronograph, which is a very small and handy chronograph installed at the end of the muzzle area. The starting pressure was 180 bar (based on Edgun gauge) and JSB Heavy (18.1 grains) was used. The first shot was low in speed (878 ft/sec), but the subsequent 35 shots were consistent with average 916.5±4.5 ft/sec (minimum 910 ft/sec and maximum 926 ft/sec). The regulator came off around 130 bars (I think) because of a little rise in speed for several shots and then the speed dropped to around 840 ft/sec for about 13 shots in parallel with pressure drop. The POI (at 30 yards) started to drop slightly (~0.2”) at shot #37 (or the regulator was off at this point?) The POI didn’t further drop until pressure went below 105 bars. I got 35 good shots consuming ~800 psi (from 180 bar to 125 bar) from a 289-cc air tube with average 33.8 foot-pound muzzle energy, which is about 13.1 bar-cc/ft-lb efficiency of air usage. If using Zoco’s data – green-line shot string, 220 bar to 130 bar for 57 shots, ~32.5 fpe (http://talonairgun.com/forum/viewtopic.php?t=19488&postdays=0&postorder=asc&start=520), I got the number 14 bar-cc/ft-lb efficiency.
Based on the data from a shot-string of Royale 400 (without regulator; average 868 fps with 37 fps extreme spread) (http://www.network54.com/Forum/79537/thread/1318702313/FX+Royale+400+.22+-+90+shot+string+with+chart-target), which consumed 0.94 bar/shot (220 to 135 bars for 90 shots) with ~30.3 fpe from a 400-cc bottle, the air efficiency is 12.4 bar-cc/ft-lb. Using another shot-string (http://airgunadvice.net/viewtopic.php?t=12183), from 220 bars to 179 bars with 36 shots (average 954 fps with 28 fps spread) at ~36.6 fpe, I got the same number (12.4 bar-cc/ft-lb) for air efficiency. Using the data from the FX Royale 400 review video of Ted in Youtube, average 33.53 fpe and 20 fps extreme spread with high power, I got 11.1 bar-cc/ft-lb efficiency. If the medium power is used (884 fps with 31.4 fpe and 13 fps extreme spread), the efficiency will be higher at 9.6 bar-cc/ft-lb. It seems Royale is a little bit better than Matador R3 (standard length) in air efficiency without much sacrificing speed variation in the un-regulator gun.
I think Edgun can be optimized by adjusting the combination of regulator and power to reach max efficiency, but it will need a lot of trial. Or this is already at the optimal condition when Ed designed and set up the gun. What do you think?
p.s
I also installed a Harris bipod BRM-S model 6”-9” in late afternoon, and ran a few shots under high-gust wind (>20 miles/hr) before dark. It seems to improve the unstable sitting of the gun and increase the shooting accuracy. 😛 Will test more tomorrow if weather is good.
All Replies
Thanks Trygve. I am curious what the rifling looks like in Cricket. Can you compare them with Matador?
With the new reg setting (4:30) and HST at 1.375 turn-in, I shot one string today to see if the speed hump at the end of the string (with stock setting) is eliminated. The average speed is about the same before and after reg adjustment. But the string is much flattened after reg adjustment. The SD is reduced from ~12 fps to ~3 fps and the speed hump is gone. Now, I have no reason to blame the POI shift possibly due to 30-40 fps changes in speed within a shooting session. I will let the gun to break-in with current settings. One thing I haven’t figure it out is the air usage is increased from ~10.5 cc-bar/ft-lb with stock setting to ~12 cc-bar/ft-lb after reg adjustment, but the number of useful shot is not reduced. After reg adjustment, the range of pressure drop is wider than that of stock setting. In next few weeks I will check the stability and consistency of the speed. My feeling is that a fine tune is needed to get SD under 3 fps with extreme spread less than 10 fps.
Some brilliant pictures and great stuf here endo ! Very nice !!!!
Cheers
Trygve 😀
Finally got a chance to adjust HST to see where the new regulator pressure is set at. My goal is to set the optimal speed at ~900 fps since I found this Matador likes this speed. The regulator is set at 4:30 o’clock (from original 12:00 o’clock). Based on the graph, the peak speed, ~905-910 fps, is at HST screw with 1.5 turn-in from zero. This is very close to what I want it to be. So I set the HST at 1.375 turn-in → around 900 fps.
Interestingly, the rifling pattern of R3 .22 and .25 barrel is different, 12 lands/grooves vs. 10 lands/grooves, respectively. Does this make .25 more accurate?
Endo
Varminter, I took the liberty to graph your string and it looks great. There are some large change in speed but I think this can be improved by fine-tuning. Sometimes it may smooth out after some shootings to let it settle. Shoot the gun for 3-4 tins to see if fine tune is needed. I use Excel to analyze the string data and then input it to GraphPad Prism software for graphing. I believe Chairgun Pro will do the same as indicated by dvdrw.
I took some pictures while cleaning the regulator/valve (Picture 1) for my new .25 long. I have to say, it does need some cleaning.
Since the “old” regulator/valve is still in my .22 standard, I don’t have the actual regulator to compare with. If my memory serves me correctly, the internal of the middle air chamber (Picture 2, right), which connects the regulatory housing (Picture 2, left) and valve housing (Picture 2, right rear) is different. The old style has a central-hole (for valve) and a side-hole and the new style has 5 holes (Picture 2, right). The air valve rod is much shorter and the spring cap is a flat o-ring type (Picture 3). The internal of the regulator seems unchanged, but the screw for pressure adjustment has changed from slotted to 3mm hex type (Picture 4). I remembered it is said this new valve improves 10-15% air consumption. PA should send me pellets this week. I hope to test the string and new valve soon.
Endo
Picture 1: The regulator/valve housing
Picture 2: Internal of middle air chamber (right)
Picture 3: Regulator washer and air valve-rod/spring – with cap
Picture 4: Regulator adjustment screw (hex type, left) and lock screw (right)
I use Hawke Chairgun Pro, under Toolbox/Statistic TAB. You have to input the string manually tho.
Endo, I got rid of the huge spike at the end of the shot string and my Edgun R3 .25 Long with the newest valve, just like yours, is now much more consistent compared to the out of the box settings. I just gave it a very quick and dirty tune using oldgoat’s video. I haven’t even checked to see if the HST can be adjusted higher and where my peak would be in relation to the regulator setting yet. I’m assuming it will improve even more once I take the time to fine tune the Reg. and HST. My shot string numbers are in the post below. Now I just need to find the graph/chart program I was using in the past. I like the one you’re using.
Varminter, I just follow what Doctor Edgun says. He said I should turn down the regulator a little and increase HST to the speed I want, and then go from there for fine tuning. So, it means we will have some work to do, keeping Matador busy. 🙂
The hump in the string might be caused by low HST. When the pressure is off the regulator (in my string it is around 130-140 bar), the pressure drops with shot, and in a relative term, the hammer strike is increased. This will let the valve open longer and let more air out, leading to speed rise. I might be able to flatten this out by increasing HST, but this will make the overall speed much higher than my target value. So, the way to “correct” it is to lower regulator pressure and then adjust HST to see if it can match the target speed and flatten out the hump. As my .22 standard, hopefully, this process will minimize the shot-to-shot variation and have a consistent speed through out the string.
Good luck.
Endo
Endo
What’s the deal with the spike/hump at the end of both of your shot stings? I ask because my new .25 Edgun Long is doing the exact same thing. I just opened everything up and turned the regulator in half a turn to see what happens. Please keep us all posted as I’d like to know how to improve mine once you or oldgoat figure this out like you guys always do. 🙂
Just wanted to see what the string would look like at my target speed (890-900 fps) before doing regulator adjustment. I increased HST by turning in ¾ turn from the last string (“First String” in the graph). The speed got up to around 890 fps. The string stared with pressure at 194 bars. Basically, the pattern between these two strings is similar but with higher air consumption in the second string. I am ready for a series of tests on the regulator since the shot-to-shot spread is quite large and the significance rise of speed toward the end. My initial impression is that the new valve/regulator is not as stable as the old one I have in my .22 standard before tune.
Endo
dvdrw, Looks like you need to turn the reg down a little more, turn the hst screw out 2 turns and slowly turn it in until you get the max speed.
If your max speed is just slightly higher than what you are looking for, you might get by with turning the hst down a little. If not, the reg needs to be turned down a little more.
When you get the strings looking the way that you want, shoot the gun untill it goes off of the reg, refill and see where you are at. Once set, the reg needs to shot down below the regs set point to “lock in” or “set” the reg.
I hope to find the time to shoot my 25 standard this Sunday.
This is the same string , but in Voltars’s graph style:
Looking good. I prefer your graph with 5 fps increment as it gives more precise representation. Move your shot count spread out to 5 for little better look as 10 gets clustered quick.
Voltars graph with 50 fps spread could make the Rockies look decievingly level.
Have you fellas not seen what a good regulator string looks like?
Confused over here!
Awesome….
Looks so much better
I missed that chart resolution.
Thank you for setting me straight! 🙂 🙂
After 1/4 increase of the HST, the velocity stabilized more. I think if I increase HST just a little more, I will have a much flatten string but I will exceed my target speed. So, I will turn down the regulator just a little more, maybe 1/8, and start over. All that tomorrow.
This is the same string , but in Voltars’s graph style:
- You must be logged in to reply to this topic.
Endo: it looks like you need to turn the reg down a just little more and then turn the HST up a little. I like to set my Matadors to shoot around 885 fps using the JSB 25.4 grain pellets.
The lower reg setting should drop your fps speeds down and the higher HST should give you a lower EV on the shot string.
You should be able to get a R3 25 long to give you 70 regulated shots with a flat shot string.