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There is one PCP that started the craze, IMO.... The Crosman/Benjamin Discovery.... Full Stop.... Of course you mean the 21st Century, right?....

IMO, the biggest variable beyond our mortal control is the wind.... If you know the drag of the pellet at various velocities, you can calculate the optimum muzzle velocity to minimize the wind drift.... For pellets, that is around 850-920 fps, depending on the range to target.... For slugs...

PCP valves operate in "partial valve lock" a lot of the time when properly tuned.... What I mean is that the hammer strike is tuned in such a way that the valve does NOT open fully.... A valve opening fully generally means the gun is wasting air.... Complete valve lock, where the hammer can't...

I had the same issue with a Hatsan I had.... off-center scope rail.... It was enough the gun felt awkward for while until I just concentrated on keeping the horizontal crosshair level, and didn't worry about how the gun felt.... Bob

Here is what I mean by checking for Scope Cant (relative to the boreline).... Set up a mirror at half the closest focus distance on your AO, and view the image of the rifle in the mirror.... Here is that image, both what you should see (L) and one where the crosshair does not intersect the...

Slugs and pellets are stabilized in a different way.... Pellets have the CG (center of gravity) ahead of the CP (centre of pressure), and are "flare stabilzed", ie when the pellet yaws, there is a correcting factor applied by the flared skirt.... Slugs have the CG behind the CP (so are naturally...

Yep, it's great, but I haven't had enough bench time yet.... Bob

You have it absolutely correct.... A properly tuned, unregulated PCP will have the velocity form a "bell curve", lower at the beginning and end, and slightly higher in the middle.... The first shots are less air at higher pressure, while the last shots are more air at lower pressure, giving the...

When you do your BC testing, don't forget to record the air pressure, temperature and humidity at your location.... It can then be corrected back to ICAO Standard Atmospheric conditions.... Bob

I was involved in the design process for these, so it warms my heart to know they are working well.... I don't have any BCs for them yet, but the previous testing I did with the similar NOE cast Hunter pellets showed the round nose with Meplat (called the Semi-Dome by JTS) had a better BC than...

Not to mention some super-duper powder, lots of it, and a really, really long barrel.... That is 22,000 FPE!.... The required twist rate would be about 2.5", and the slug about 1.9" long!.... Bob

As to the question posed, the .183 cal should have the advantage in BC.... It should have the lowest Form Drag, and since they all have the same SD, a higher BC, as BC = SD / FF.... Bob

Thanks for creating this Section on the HAM Forum, I think it will prove popular.... Bob

Meh, it happens to all of us!.... Thanks for 'fessing up!.... The KO Mk2 use a smaller body with a flare at the base to reduce bore drag.... yet maintain a good seal.... Bob

Sorry, I don't know anything about Chairgun Elite+.... The FF is the CD of your slug divided by the CD of the drag model chosen at that velocity.... Therefore the FF is different when you change drag models.... Most ballistics calculators don't allow you to input the CD, because it is difficult...

Actually, they are all nearly the same length, and they all are the same SD.... However, the smallest calibre slug should have lower form drag, and since BC = SD / FF, a higher BC.... Bob

That is a common misconception about wind drift.... It is not proportional to the time of flight, but the "lag time", which is the difference between the actual time of flight and what it would be in a vacuum.... This is why the sudden increase in drag in the Transonic region (Mach 0.8-1.2) has...

It is not new, it has been around for years.... It is "blunt" compared to the G7, as that one has a spire point.... It is not very similar to our slugs in shape.... Here is a chart showing various Drag Models.... So far, the RA4 profile is the best match for out airgun slugs.... It is...

OK, so down to the nitty-gritty of how this new thinking results in a range of calibres I find best for the job at hand.... a long range slug gun.... If you look at the first chart in the last post above, and determine the maximum slug weight for each calibre, you will find the following for...

Those of you who have been following my articles will remember that there is a way to calculate the absolute maximum FPE that a PCP can produce.... You take the bore area times the pressure, and multiply by the barrel length, and you end up with the total FPE that can be produced.... However...