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

After reading the discussion from Sir Ville and SECoda with those fancy triggers. I am curious about the trigger weight in my current setting. I don’t have the gauge to directly measure it. So I hung a small plastic bag to the trigger and gradually put some weight (pellets) until it breaks. To my surprise, it was about 15 oz. I thought it should be less than 8 oz, but I was totally off. 😳
On the other hand, “front-trigger for all” adjustment can easily achieve an 8-oz trigger with secured sear engagement. I kind of like it set around 8-10 oz (target shooting and kill mosquitos and flies around 40-50 yards). My only “complain” is that the first stage is very short. I will play around to get use to it.

When I was testing trigger setting, I found my shooting didn’t group well from a new tin. This tin (JSB, 18.1) was from a batch ordered from PA late last year. I measured the head size, with a majority of 5.49 mm, in a few tins from that batch. I assume it should be 5.49 mm head in the tin I was shooting. But I was wrong, I measured the whole tin of the pellet and a majority of them is 5.47 and 5.48 mm. The other tin from the same batch is also, 5.47-5.48 mm. I know my matador hates these sizes. But I wanted to test them again. I gave those sorted pellets (see picture) to wife and asked her to hand me 5 pellets from the group randomly without letting me know the head size. I shot 5-shot group for 3-5 groups for those pellets at 30 m target. The gun was off regulator at 115 bar and tethered with an air tank with 115 bar to eliminate the regulator factor. She made a note on the group of target I shot and at the end she matched the note with the target group and head size. She measured edge-to-edge for each group, and minus a constant 0.22”. Here is the average result for each group:

5.50 mm – 0.106”
5.49 mm – 0.191”
5.48 mm – 0.219”
5.47 mm – 0.268”

I was thinking we should have a “pellet exchange program” here to trade out the “bad” tins because one man’s trash is another man’s treasure.

I am a bit surprised your trigger was finicky at around 15 ozs. I have not noticed anything strange down to about 8 oz which I toyed with early on. 10-12 oz seems like a safe compromise for the standard stock triggers in the Edguns and Crickets so I went with 12 like my PBs.

The consistency of diablo pellets just stinks- even on JSBs. I am sure for a lot more money JSB can get them much closer but I suspect the number of us that would want them is somewhat limited from the typical shooter.

After 750 shots and 4 cleanings, trigger polishing and adjustment, HST adjustment, probe oring replacement, and muffler clipping resolution on my .30 cal Matador I can state that I can no longer tell a difference on accuracy out to 50 yards between my .25 Standard R3 Matador and the .30 cal Standard Matador. Both consistently shoot at 1/2″ at 50 yards. All I am doing on the JSB 44.75 pellets is looking for any damage at this point. My best 5 shot group with the 30 cal has been 3/8″ . Both guns are fabulous for very accurate pesting and hunting. The winds are normally none to low in the valley I live in but the 30 cal does well even moderate wind at less than 50 yards with the .043 approx. BC. It is definitely my favorite small game hunting airgun at this point. Small, light weight, accurate, powerful, and very quiet. I couldn’t be happier. 😀