by Tom Gaylord
Writing as B.B. Pelletier

Air Arms TDR rifle
Both side of the Air Arms S410 TDR.

Part 1

This report covers:

  • Equipment malfunction
  • Why a pump?
  • A different test
  • Loading and cocking
  • No double feeds
  • High power
  • The end of the power curve
  • Low power
  • Medium power
  • Trigger pull
  • Butt adjustment
  • Observations so far

Today we test the velocity of the .22 caliber Air Arms S410 TDR Classic. Because it has a power adjuster, we will look at power on the high, medium and low settings. We will also look at the shot count, how easy the magazine is the load, the trigger setting and generally how the rifle functions.

Equipment malfunction

In Part 1 I said I would test this rifle out at the range because of the loud report, but an equipment malfunction plus the weather caused me to change my plans. The malfunction was my Hill pump that has been reliable until now. When I hooked it up to the TDR out at the range it failed to operate. That’s probably because I don’t use it very often and these things need to be exercised or they will seize up. I will continue to exercise it and hopefully get it running again.

Fortunately I hadn’t returned the Air Venturi G6 hand pump to Pyramyd Air yet, so when I returned home I unpacked it and put it into operation. This is the only hand pump I have that works at present, so I think I will buy it from Pyramyd Air. It’s the only hand pump that comes with the parts to overhaul it in the box with the new pump.

Why a pump?

Why am I using a hand pump for this rifle? Why not just fill it from my carbon fiber tank like every other PCP I shoot? Well, Air Arms puts a proprietary fill adapter on their PCP guns. It mates to nothing else. The threads are 1/8-inch BSP, so it will attach to almost all hoses, but nobody makes an adapter to go from the Air Arms adapter to an industry standard Foster quick disconnect adapter. So my CF tank won’t connect. I am not going to take my CF tank hose apart because I use it on so many other airguns, so another way to fill had to be found. Hence the pump.

If you want to see a picture of the fill adapter for the TDR, go to Part 1. It is shown next to the place on the rifle it must be installed.

A different test

My normal velocity test is shooting 3 different pellets to see their velocities. But when a rifle has adjustable power the test becomes more complex. So this test will be different. I selected just one pellet for today’s test — the JSB Exact Jumbo 15.89-grain dome. I will shoot that pellet on high power, low power and medium power. I will also get a shot count on high power and either low or medium power — whichever makes the most sense. That will entail a lot of shooting and should tell us what we want to know about the rifle. Let’s begin.

Loading and cocking

The 10-round magazine is advanced by the rifle’s action mechanically. There is no spring to be wound up or set. Therefore, loading the magazine is as simple as dropping a pellet into each chamber and advancing the rotary clip inside the magazine to the next chamber. There is nothing you need to hold or restrain.

The loaded magazine slides into the rifle’s receiver from the left side. The only precaution to take is to make sure the bolt is completely retracted and out of the way.

No double feeds

The bolt is stiff and hard to cock. I think it will break in as the rifle is used, but for this test I had to watch it or it wouldn’t cock all the way. It does advance the magazine to the next pellet though. If this happens, you can feed a second pellet into the breech. To prevent that just remove the magazine and cock the rifle. Then insert the magazine and everything will be fine. I had to do this one time, but the rifle never fed more than one pellet throughout the test.  Toward the end of the test after 80 shots had been fired I was getting used to cocking it and it did seem easier.

High power

I filled the rifle to 200 bar, which is 2900 psi. That’s the maximum fill pressure recommended by the manufacturer. Then I started shooting. The first 10 shots averaged 838 f.p.s. The low was 827 f.p.s. and the high was 853 f.p.s. That’s a 26 f.p.s. spread. At the average velocity this pellet generated 24.78 foot pounds of energy at the muzzle.

The second 10 shots averaged 868 f.p.s. The low was 857 f.p.s. and the high was 873 f.p.s. So the spread for this string was 16 f.p.s. At the average velocity the pellet produced 26.69 foot pounds of energy.

The third 10-shot string averaged 848 f.p.s. with a low of 825 f.p.s. and a high of 865 f.p.s. The spread for this string was 40 f.p.s. and the muzzle energy for the average velocity is 25.38 foot-pounds.

This third string was in decline for nearly all shots. It was clear to me the rifle was coming down off the power curve. So I say there are a total of 30 good shots on a fill when the gun is set to high power. The total spread for those 30 shots runs from a low of 825 f.p.s. to a high of 873 f.p.s.. That’s 48 f.p.s., which seems a little excessive.

If we limit the rifle to just the first 2 magazines we get a spread that runs from 827 f.p.s. to 873 f.p.s. That’s still a total of 46 f.p.s. over the 20 shots, so we might as well include the third magazine. I will shoot the rifle at 50 yards and see what these velocity swings do to the point of impact.

After 30 high-power shots the gauge on the rifle said there was 145 bar of pressure remaining. That’s 2,103 psi.

The end of the power curve

I knew from looking at the velocities of the third magazine that the TDR was at the end of its useful shots on high power, but for the benefit of the newer airgunners I did fire an additional 10 shots — just to see what happened. Here are those shots in succession.

Shot……………Velocity f.p.s.
31………………….819
32………………….814
33………………….810
34………………….804
35………………….798
36………………….789
37………………….785
38………………….777
39………………….776
40…………………760

I’m not going to factor these shots into the calculations because they are clearly off the power curve. I just wanted to show them so you could see that the rifle really does have just 30 shots on high power.

Low power

After shooting 40 shots the rifle was sitting at 110 bar (1,595 psi). It took 94 pump strokes from the G6 hand pump to get back to 200 bar. Then the power was adjusted to the lowest setting and I shot 10 shots. They averaged 390 f.p.s. with a low of 385 f.p.s. and a high of 394 f.p.s. So the spread was 9 f.p.s. on low power. The average velocity is generating 5.37 foot-pounds at the muzzle. But nobody is going to buy the TDR to shoot this slow. This led to the decision to advance the power setting to medium and try another 10 shots.

Before I move on, though, consider this. You now know the range of velocity/power the TDR will give you. It should be possible to find several sweet spots within that range.

Air Arms TDR rifle power setting
This is where I set the power for medium.

Medium power

All I did to set the power to medium is turn the power knob until the indicator on the left side of the receiver was centered in its range. A session at the range is needed to confirm that this is where the gun wants to be. I had already shot 10 shots on low power when I started this session, and the gun was not topped off after those shots.

The first 10 shots on medium power (but the second 10 after filling the gun) averaged 761 f.p.s. They ranged from a low of 756 f.p.s. to a high of 767 f.p.s. — so the spread was 11 f.p.s. That’s considerably less than the spread of the first 10 pellets on high power. At the average velocity these pellets generated 20.44 foot-pounds at the muzzle.

The second string of 10 shots averaged 760 f.p.s. — just one foot per second slower than the first 10. The range went from a low of 755 f.p.s to a high of 766 f.p.s. That’s also 11 f.p.s. total spread. If we combine the two strings, the total spread is just 12 f.p.s. That’s almost one-quarter the spread of the first two strings on high power (46 f.p.s.). At the average velocity this string put out 20.38 foot-pounds of energy at the muzzle.

The third string, however, fell off the power curve. These were shots 31 through 40, because of the initial 10 low power shots. Here is the string.

Shot……………Velocity f.p.s.
1………………….754
2………………….745
3………………….751
4………………….739
5………………….740
6………………….733
7………………….734
8………………….734
9………………….729
10………………..728

As you can see, the velocity dropoff isn’t as severe in this fourth string as it was in the fourth string on high power, and it also doesn’t start with the first shot. Nevertheless, there does seem to be about the same 30 good shots at medium power as there are at high power. These shots are a lot more stable, though, and perhaps that stability will show up in the 50 yard accuracy test.

Trigger pull

As it came from the factory the test rifle had a 2-stage trigger that broke at 1 lb. 13 oz. The second stage was crisp without any creep so I left those adjustments alone. All I adjusted was the weight of the trigger pull. When I finished it broke at 1 lb. 5 oz. That’s light enough for me. The pull weight was uniform, shot to shot, which makes this an easy trigger to get used to.

Butt adjustment

While I was at it, I adjusted the rubber buttpad as low as it would go, to bring the cheekpiece up higher. It still lacks about an inch of reach for me in the offhand position (the scope is too high), but it will be pretty good off a sandbag, when I am leaning forward.

Observations so far

The TDR has all the power it’s advertised to have, but it’s much stabler on a lower setting. The shot count is higher than I expected, but it doesn’t seem to increase by a significant amount as the power is adjusted down — at least to the medium point. Thirty shots per fill are what you can count on from the medium to high-power settings.

The trigger is light and crisp. The trigger adjustments work very well.

The butt attaches and detaches quite fast. Once attached, the rifle is rock-solid. I look forward to trying the rifle at 50 yards.