Edgun R3 .22: Shot String, Air Efficiency, & Trigger

This is an update, and a long post, on the shot string and air efficiency of my Standard R3 .22 Matador after regulator adjustments. The goal is to tune the gun to shoot at 890 fps with the highest standard described by Dr. Edgun: “3-4 fps shot to shot variation and a max speed spread of 10-12 fps”. I have played around the reg lately and my previous strings showed a creeping down of speed with shots (reducing ~6 to 8 fps; see previous post). I was not happy with it. So I re-adjusted the reg pressure and did some fine tune on HST. Here is what I have learned from tuning the Matador. I thought it might be useful to those who are interesting in optimizing the gun.

The goal is to get an optimal reg pressure and HST for speed ~890 fps (the range of best accuracy). Here is the protocol for my tuning:
1) Adjust reg to where you think it should be for the target speed (in my case, 1/3 trun-in from the stock setting to start with)
2) Fill the gun and turn the HST two turns out (reduce HST)
3) Shoot 5 pellets to ensure the HST is reduced enough to the speed around 100 fps below the target speed (my target speed is 890 fps)
4) Shoot 5-shot groups for each increment in HST (i.e., turning in the screw 1/8-turn for each tension increment) and record the speed vs. tension.
5) The amount of speed increase vs. tension increment should taper off and reach the plateau (this should be the optimal tension for the reg). The speed will drop if you further increase the tension. This is commonly referred as “1st peak” (but I stopped when speed reaches plateau)
6) The optimal tension might not match the speed you want (e.g., if the speed is lower than the target speed, see #7 below)
7) Increase reg pressure (or decrease reg pressure if the speed is too high)
8) Repeat the process from #2 to #7 (goal is to find the balance between the reg pressure and the HST for the desire speed).
9) END the loop if the goal is achieved.

Here is an example of the speed vs HST in two of my adjustments. The open triangle in the 1st graph shows the reg is set to 0.375 turn-in (135˚) from the stock. The speed is increased with increasing HST and reaches plateau around 2.5 turn-in with speed 880 fps. I further increased HST (3 turn-in) in the plateau region to reach the target speed 890 fps. In this setting, 194 bars starting pressure (gun gauge), I got average speed of 890.3±2.6 fps with 14 fps maximum spread and average 2 fps variation between shots (see 2nd graph). I had about 57 shots before a significant speed drop. There is no creeping in this string. I like these numbers. But the air efficiency (~14 cc-bar/ft-lb) is relatively low compared to the stock setting (about 13 cc-bar/ft-lb). This means that a larger amount of air is required for spitting out one ft-lb energy (lower value indicates better air efficiency). I think the reg pressure was set too low to effectively reach my target speed. To compensate that I had to increase HST beyond optimal level, and this would have caused a significant waste of air. As Dr. Edgun said “Edgun Matador owners are a bunch of picky bastards!” and I think he is correct. I re-adjusted the reg to increase pressure (0.25 turn-in, i.e., 90˚ from the stock) and the gun speed reached plateau at 890 fps with less effort (2.375 turn-in HST, 1st graph). The shot string, with 193 bars starting pressure (gun gauge), is now average 889.8±2.7 fps with 11 fps maximum spread and average 3.2 fps variation between shots (2nd graph). The calculated air efficiency was improved to 12.4 cc-bar/ft-lb (see the smaller slope of pressure-line with closed circle in 2nd graph) and the shot count was increased from 57 to 65 before dropping in speed. This setting also gives me some room to increase speed when I need it (of course at the expense of reducing air efficiency). But, again, I was not happy with some (3) shots exceed 9-fps change and a slight creeping up in speed with shots. So, I increased the HST a little bit to see if these hiccoughs and creeping can be cured. Now, I got 892±2.2 fps with 9 fps maximum spread and average 2.2 fps shot to shot variation (one hiccough with 6 fps). The speed creeping is gone. The air efficiency reduced a little bit to 12.8 cc-bar/ft-lb with 60 regulated shots. I gain something also lose something. I think the Matador has been pushed to its limit.

I see several benefits from this tune. Statistically, it has 1) significantly reduced the speed variation between fills, 2) significantly reduced the maximum spread of speed, 3) significantly reduced the speed variation between shots, 4) significantly improved air efficiency if HST is set to optimal level, 5) significantly increased the number of regulated shot. Non-statistically, I feel a lot better on my confidence on the gun. But the quest for the Optimal Edgun is never ending. In fact, the stock Matador shoots well, and there is no need to do these tunes if you are not picky on speed variations and air efficiency (either between fill, within fill, or between shots). Matador will still kill what he’s supposed to kill effectively and even kill what he’s not supposed to kill such as my double-pane windows. 👿

In the tuning process, there was a lot of try-and-error and many small incremental adjustments. I have used at least 4/5 tins of pellets and lots air. Without the advice and help from Dr. Edgun (Oldgoat/Tedd), this tune would not be possible. The de-gas tool he sent me has made the reg adjustment much easier and efficient, and the HST screw he made is also very useful. Thank you!

Hopefully, this post is helpful to those who want to push the Matador to its maximum potential.

Next focus will be the accuracy…. I think this is the most interesting and important one.
Regards,
Endo

HST vs Speed

Shot String Comparison

BigB, my gun was made (assembled) in Estonia too (serial no. 3).:D
Yes, the first stage is very short. In my gun, the fist stage disappears when you are doing a second pull on the trigger. This is different from yours. In earlier posts, Dr. Edgun gave some tips for adjusting/lightening the trigger. He said “try turning the rear trigger screw almost all of the way out and then turn the front screw in until the gun will not cock. Then turn the front screw out till you like the trigger.” Hopefully, this is helpful.