MicroStrike tuning is a big part of the product attraction. You can easily change the regulator setting and hammer spring tension settings. Plus, it’s easy to de-gas the gun in order to make reg setting changes.
Everyone will want to tune their MicroStrike. But how, exactly? That’s what we are covering in this article.
Air Venturi MicroStrike Tuning – Before Starting
Let’s start with some real basics…
You cannot tune a PCP air rifle without a Chronograph to capture the Muzzle Velocity. So – if you don’t have one – buy one. Preferably a good one. Don’t even think of trying to tune an airgun without one!
Secondly you need a way to record and compare the data you generate. This can be as simple as writing things down with a pen and paper. That’s what I do.
Next, having recorded the data, you need to analyze it. I do that using a computer spreadsheet. But you could do that on paper, too.
The really important thing is to record stuff! If you do not record the data you generate when tuning, it will be much more difficult to draw conclusions later.
Finally, change one thing at a time!
If you change more than one thing – say reg pressure AND hammer spring tension – at the same time, there’s no way to know which made the difference.
A little structure in the tuning process will go a long way to helping achieve the results you want.
Air Venturi MicroStrike Tuning – Strategy
OK, we have decided to tune the MicroStrike. The first decision is to settle on the caliber.
I am using a .22 caliber gun because that’s what I have. But – although it’s easy to change calibers on the MicroStrike – each caliber will require a different tune to be effective. Don’t tune for .177 caliber and then expect great results if you change the barrel to .25 cal!
The second is to decide on the pellet you plan to use with the gun. The best tune settings for a very light pellet will likely be different from those for a heavy pellet. So you might want to do some basic accuracy testing first to determine which pellet works best with your specific gun. Check our HAM review for some initial suggestions.
The next is to decide what you are tuning for. There’s plenty of possible objectives for tuning a PCP airgun, so select one and stick to it.
You could decide to tune for maximum power, maximum shot count, best consistency, best accuracy, or a blend of these factors that matches the way you want to shoot your MicroStrike. But – whatever your choice – make one and stick to it!
My strategy for this article is to share some of the basic techniques I used, together with some results for “maximum shot count” and “maximum power” settings. The aim is to generate information that will give you a good place to start with your own tune.
For this reason, I selected a “standard” pellet for all my testing in this article. This is the H&N Baracuda 18. At 18.1 Grains weight, this is a known high-quality, consistently-manufactured pellet.
Using one pellet type makes it much easier to compare data. It removed another variable from the analysis.
Air Venturi MicroStrike Tuning – Hammer Spring Adjustment
When tuning any PCP air rifle, my preference is to start by adjusting the hammer spring tension.
True, adjusting the regulator is the fastest way to produce large changes in performance. But small changes to hammer spring tension provide a more subtle approach that will pay dividends – as we will see later.
My starting point was to test the MicroStrike in the condition we received it at HAM. For whatever reason, this particular gun was set to a “maximum shot count” configuration.
The regulator was set to minimum operating pressure (1,100 PSI) and the hammer spring just a quarter turn in. So that’s where I started…
Note that I was reading pressures from the MicroStrike’s two built-in pressure gauges. They checked as pretty accurate against my big compressor gauge readings.
I ran Muzzle Velocity tests at a variety of hammer spring settings. First at the 0.25 turn-in default, then at 0.75, 1.5 and 2.5 turns.
Although the MicroStrike offers a maximum hammer spring compression of about 6 turns-in, my experience is that small changes in the hammer spring setting can make large differences in Muzzle Velocity and consistency. Don’t get too radical with hammer spring adjustments!
For consistency, I backed the hammer spring adjuster right out to its stop every time (turning counterclockwise). Then rotated clockwise to the next setting.
To save time and pellets, I also made most of these “maximum shot count” tests using a 3,000 PSI fill. Then I re-ran at the full, 4,350 PSI fill once I had my base data.
Air Venturi MicroStrike Tuning – Maximum Shot Count Results
Now let’s look at the data I collected from this series of tests.
| Test 1 | Test 2 | Test 3 | Test 4 | Test 5 | Test 6 | |
|---|---|---|---|---|---|---|
| Hammer Turns In | 0.25 | 0.25 | 0.75 | 1.50 | 2.50 | 0.75 |
| Fill Pressure | 4,350 PSI | 3,000 PSI | 3,000 PSI | 3,000 PSI | 3,000 PSI | 4,350 PSI |
| Reg Pressure | 1,100 PSI | 1,100 PSI | 1,100 PSI | 1,100 PSI | 1,100 PSI | 1,100 PSI |
| Pressure Drop | 3,250 PSI | 1,900 PSI | 1,900 PSI | 1,900 PSI | 1,900 PSI | 3,250 PSI |
| Consistent Shots | 45 | 27 | 27 | 26 | 26 | 47 |
| Average Muz. Vel. | 542.37 FPS | 534.74 FPS | 541.71 FPS | 531.00 FPS | 526.22 FPS | 534.12 FPS |
As you can see, Tests 1 and 2 had the same settings but with a different fill pressure. Likewise for Tests 3 and 6. Here we see the full string of 47 consistent shots from Test 6 – 1,100 PSI regulator setting and 0.75 turns on the hammer spring.
In fact, this represented my favorite “high shot count tune” with this gun using H&N Baracuda 18 pellets. It’s ideal for happy plinking at under, say, 30 Yards range. Which is what I like to do!
Having this base performance data, I also analyzed it to understand where this particular MicroStrike was performing with regard to efficiency. Here’s what I found…
| Test 1 | Test 2 | Test 3 | Test 4 | Test 5 | Test 6 | |
|---|---|---|---|---|---|---|
| Hammer Turns In | 0.25 | 0.25 | 0.75 | 1.50 | 2.50 | 0.75 |
| Stan. Dev. | 7.75 FPS | 7.59 FPS | 7.43 FPS | 5.66 FPS | 7.93 FPS | 7.61 FPS |
| Ave Muz. Energy | 11.84 Ft/Lbs | 11.52 Ft/Lbs | 11.82 Ft/Lbs | 11.36 Ft/Lbs | 11.15 Ft/Lbs | 11.49 Ft/Lbs |
| Total Energy | 533.15 Ft/Lbs | 310.95 Ft/Lbs | 319.10 Ft/Lbs | 295.23 Ft/Lbs | 289.96 Ft/Lbs | 540.03 Ft/Lbs |
| Energy/Pres. Drop | 0.164 | 0.164 | 0.168 | 0.155 | 0.153 | 0.166 |
| Average Muz. Vel. | 542.37 FPS | 534.74 FPS | 541.71 FPS | 531.00 FPS | 526.22 FPS | 534.12 FPS |
One interesting thing to appear from this analysis is that the Standard Deviation (measurement of shot-to-shot consistency) was clearly best at 5.66 FPS across 26 shots for 1.5 turns in on the hammer spring.
Another observation is that the efficiency of this gun/pellet combination was best at 0.75 turns in on the hammer spring. I calculated this by taking the sum total of the “on the regulator” Muzzle Energies and dividing this by the difference between fill and regulator pressures. This was the 0.168 recorded in Test 3 and 0.166 for the same settings but higher fill pressure in Test 6.
Given this analysis, my next step would be to try testing with the hammer spring adjuster one turn in at the 1,100 PSI regulator setting. That would likely be ideal!
Air Venturi MicroStrike Tuning – Regulator Setting
The MicroStrike Owner’s Manual gives the maximum regulator pressure as 3,000 PSI. As received, the test gun showed 1,100 PSI on the reg gauge – the minimum.
OK, so I knew the max and min settings for the regulator. What I didn’t know was how many turns of the regulator setting wheel would be required to go through that range.
So I made a very crude – but effective enough – indicator. It was a strip of self-adhesive, flexible plastic. Having measured the diameter of the HPA tube, I cut the plastic to match the circumference (120mm). Then I marked quarter and eighth turns on the plastic and stuck it on the regulator adjustment ring.
Voila! Now I was able to make (reasonably) precise turns of the regulator adjustment ring and read off the reg pressure from its gauge. Then I shot a string to find the FPS and Muzzle Energy of the Baracuda 18s at that setting.
NOTE: It’s vital to remove all pressure from the gun before adjusting the regulator set pressure, whether going up or down. However there’s a de-gassing screw conveniently-placed and the low HPA capacity of the MicroStrike made the pressure release process very easy.
Here’s what I found…
| As received | Plus 1/4 turn | Plus 1/2 turn | Plus 5/8 turn | |
|---|---|---|---|---|
| Reg Pressure | 1,100 PSI | 1,350 PSI | 2,200 PSI | 2,800 PSI |
| Average Velocity | 530.38 FPS | 632.45 FPS | 723.21 FPS | 766.45 FPS |
| Muzzle Energy | 11.34 Ft/Lbs | 16.11 Ft/Lbs | 21.06 Ft/Lbs | 23.65 Ft/Lbs |
Firstly, I was surprised that the difference between minimum and maximum regulator settings was just 5/8 of a turn. Somehow I expected it to be more.
Secondly, then I could plot a graph giving an approximate correlation between the rotational setting of the regulator adjustment ring and the corresponding pressure. Here it is.
From this graph, I would have a good idea of where to set the regulator ring, should I have a specific reg pressure in mind. However, I wanted to explore a maximum muzzle energy tune, so I left it in the plus 5/8 turn position.
Air Venturi MicroStrike Tuning – Maximum Power Results
Now I started to test the gun at full regulator pressure and with different hammer spring adjustment settings. Same procedure as before.
| Test 7 | Test 8 | Test 9 | Test 10 | |
|---|---|---|---|---|
| Hammer Turns In | 0.75 | 1.50 | 2.0 | 2.50 |
| Fill Pressure | 4,350 PSI | 4,350 PSI | 4,350 PSI | 4,350 PSI |
| Reg Pressure | 2,800 PSI | 2,800 PSI | 2,800 PSI | 2,800 PSI |
| Pressure Drop | 1,550 PSI | 1,550 PSI | 1,550 PSI | 1,550 PSI |
| Consistent Shots | 6 | 10 | 9 | 8 |
| Average Muz. Vel. | 762.33 FPS | 765.00 FPS | 764.00 FPS | 765.83 FPS |
This is where the potential effect of hammer spring tension really becomes obvious!
| Test 7 | Test 8 | Test 9 | Test 10 | |
|---|---|---|---|---|
| Hammer Turns In | 0.25 | 0.25 | 0.75 | 1.50 |
| Stan. Dev. | 7.85 FPS | 2.50 FPS | 4.72 FPS | 3.34 FPS |
| Ave Muz. Energy | 23.40 Ft/Lbs | 23.56 Ft/Lbs | 23.50 Ft/Lbs | 23.61 Ft/Lbs |
| Total Energy | 140.42 Ft/Lbs | 235.63 Ft/Lbs | 211.54 Ft/Lbs | 188.94 Ft/Lbs |
| Energy/Pres. Drop | 0.091 | 0.152 | 0.136 | 0.122 |
| Average Muz. Vel. | 762.33 FPS | 765.00 FPS | 764.00 FPS | 765.83 FPS |
As we can see, just three quarters of a turn more hammer spring tension makes a HUGE difference between the results from Test 7 to Test 8! Here’s the shot curve from Test 8.
Air Venturi MicroStrike Tuning – Conclusions
As we can see – using the same pellets – it was easy to make the same gun produce either 47 consistent shots at 11.49 Ft/Lbs Muzzle Energy or 10 consistent shots at 23.56 Ft/Lbs Muzzle Energy. The comparison could be even more extreme had we used lighter pellets for the low power and heavier pellets for the high power tests.
Plus, it would be possible to make an alternative tune pretty-well anywhere between those extremes.
Interestingly, the most consistent (lowest Standard Deviation) strings were achieved with the high power tunes. The minimum was an outstanding 2.50 FPS Standard Deviation for Test 8.
The maximum power tunes did, indeed, deliver the highest power based on the Muzzle Energy of individual shots. However the highest power – based on the TOTAL Muzzle Energy of the shots fired down to the regulator set-point – was far greater for the low power tune.
In fact, the total Muzzle Energy was 540 Ft/Lbs for Test 6, compared to just 235 Ft/Lbs for Test 8.
So the MicroStrike is clearly much more efficient with its air at lower power levels. My guess is that this is due to the short barrel. The gun is LOUD at any setting, but hearing protection was definitely required at the high power settings.
I hope that this article has given you some background and inspiration for tuning the Air Venturi MicroStrike. It’s definitely a very versatile airgun.
But the basic principles of what I did here could be applied to most any PCP air rifle having externally-adjustable regulator and hammer spring settings, together with simple de-pressurization capability, as well.
Have fun!!!
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Air Venturi MicroStrike PCP Air Pistol 0.177
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