Air Strippers - what if the barrel itself was a cone??

[Lol Moore]

Day off, few hours shooting this morning, couple of hours in the workshop fettling

I have touched on this before, when looking into muzzle end shapes - not crowns as I see that as the intersection where the very point the internal bore meets the end face of the barrel.

Advised logic is to have some form of concave end be it the mythical 11 degrees, or just a recess, its always said this is to protect the crown - makes sense, but...

When is the last time you saw a PCP with nothing on the end, moderator, stripper, brake, shroud??

I have always had a sceptical view of the common belief of how strippers work, that is the stripping away of turbulent air so not disrupting the pellet, I am not so sure about that.

However my limited experience is one advantage lies in reducing muzzle flip by disrupting/dispersing the jet that comes out the end, in that sense they work (don't like brakes that send the air up - in winter it masks the view of the pellet flight).

I also absolutely believe they act as surrogate barrel tuners when people move the cones around so altering the harmonics.

So in those senses they do have a positive effect, however every time I look at one I think if the idea is get as much of the jetting air away from the pellet as quick as possible surely a concave ended muzzle is not the best idea - what about a cone facing a cone?


https://photos.app.goo.gl/39y3XrXuxXAq5DXw2


I would like to try it with a long thin type adjustable stripper but only have a Steyr double cone so machined a Lothar barrel end like the cone of the stripper and placed the crown such that the edge of the head of the pellet is just entering the cone before the tail leaves the crown.

Result, well it definitely sounds different, still loud but less of a crack, accuracy, just shot 30 through it benched out to 40 yards and definitely tighter than the bare barrel, maybe even a tad tighter than with the shroud that was fitted....need to shoot some more, maybe next week.

[air-tech]

I guess only high speed photography that can make out gas flow - sorry I don't remember how it's done, but the Cardews did it - will show what is going on and the differences between a near flat muzzle end, and the cone you have created.

Theoretically the cone shape will allow air from around the muzzle to flow more easily in the direction of the muzzle blast - the blast itself is high pressure but flowing forwards it will create a low pressure zone around it just as it exits and should "pull" surrounding air - the cone ought to make it easier for this to happen, so the blast ought to be somewhat smoother. But it's also a question of time - if the blast were a continuous flow that's one thing, but since it is not, there may not be enough time for any of this to happen meaningfully - the pellet may well already be several metres from the muzzle by then.

One of those things where you either need specialised equipment to understand what is happening, or you just compare end results and conclude that something is or is not working, even though you may not understand exactly why.

[eyebull]

I wonder if there is a (safe!) way of colouring the air, to make it easier to discern what is going on when viewing in slow-motion?

[Turnup]

Schlieren photography can reveal small density changes in air (such as caused by turbulent air flow) and can be combined with video recording or flash illuminaton. It might be necessary to construct a stripper from some transparent material to allow a full visualisation.

[steviep]

I used to have a Ripley ar5s were the barrel was machined like that.Probably the most accurate least pellet fussy rifle I’ve had.Should never have sold it.

[RobF]

There's a big difference between a shock wave and flow. One is a pressure wave propagating through the medium, the other is the medium moving.