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Air Stripper gap?

I have a RAW Micro Hunter in .177 caliber and am playing with the air stripper. What should the gap be between the cone and the end of the barrel?

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???.. 1 to 2 pellet sizes they claim .. so a .177 gap is .177 or .354 or between +/-

Now I'd guess that would be a starting point per caliber then you'll need to shoot the gaps and see what really works out .

Google hatsan airs stripper gap or adjustment there was a few posts on it around.. maybe ones got extra over that advice ..
 
The airstripper gap question can't be answered in a vacuum :). Experimentation with your system will help answer that question, but the answer is, it depends on the configuration of the rest of the system.

I would start with the length of the pellet you want to shoot, so the head of the pellet starts being protected from the uncorking blast as soon as the skirt starts to clear the muzzle. A smaller gap offers more initial protection, but allow more air through the air stripper bore after the pellet. If you doubt that, think of a very small gap. The air wants to flow straight across the gap, with not enough of a "leak" to strip off much air.

The application and power level for caliber matter. Low power for target shooting and you might find the sweet spot for the gap at one caliber air stripper gap. For higher power, the sweet spot is likely to be two calibers, or more. How can that be, as higher power means more air? If the pellet is travelling twice as fast, it spends less time in the "blast zone" before travelling into the more air-still shadow after the air stripper lip. Or, looking at it this way, at twice the velocity, a pellet spends the same amount of time crossing twice the gap as one at half the velocity, crossing half the gap.

The wider the air stripper gap, the more air it strips from behind the pellet: It is the instantaneous bulk air pressure ahead of the muzzle that drives the radial dispersion of that air into the lower pressure ambient. Actually, that "ball" of air is also expanding forwards, faster than the pellet ahead of it. The air stripper is intended to block the portion of that air that is trying to overtake from behind the pellet and upset it its "flight". At low muzzle pressure, more of the air from the muzzle is trying to follow the pellet, but there is less air in total to buffet the pellet. So, a bit of "swings and roundabouts".

If you look at shrouded PCPs that shoot at "hunting power", their air strippers are often 1/2 to 3/4" ahead of the barrel muzzle. Here, the goal is to reflect as much air as possible to the rear of the shroud for noise reduction, while still yielding field acceptable grouping ability. My observation is that such an air stripper can be spaced further from the muzzle without hurting groups at a given power, if the shroud ID is larger. Now, open air stripper function purely to minimize groups, so their spacing is optimized for that, with no consideration on the effect on sound - as they have very little to no effect on that.
 

And this one guy's results are supposed to represent what everyone else will see? Will it even repeat if he runs this test again? Is a single five shot group at each setting able to prove anything? What about at twice the FPE?

Why does the manufacturer of the stripper in the video recommend a one caliber stripper gap, if less than half a caliber is so much better? How much of each setting is air stripping related, and how much is attributable to changes in barrel harmonics?





My advice was to test your own system and optimize it based on your own results. How is that a WAG?


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My advice was to test your own system and optimize it based on your own results. How is that a WAG?
I was saying this guy did his own testing. Got results he is happy with and shared them.
Some people WA Guess what would be a correct answer. I'm with you, do your own testing and lots of it. You need quantitative results. I know what works for me. And what I use inside 20 yards isn't what I use at 50
 
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My two calibres (.22 and .25) I am using for rings shooting only, so the POI is clearly readable. Power levels between 40 and 70 fpe.
I have couple shroud-internal mounted air strippers, and also these are the open vent I was using the most:

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The one on the far left is the eaglevision, quickly became my favourite choice.... and the cone is fixed distance.
 
Yea that video tests are bananas, unless he repeated the test at least 10 times with each distance to eradicate the chance that its simply inconsistency due to pellet head/weight or guns air release presenting variations in the data.

Frankly, I have no skin in this game, I didn't know air stripper distance from muzzle bared any significance on group size. Today I learned.

-Matt