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Has anyone experimented with boat tail design for airgun projectiles?

Yes I heard about Charlie and his experiments, but I am talking about normal pcps we fill to 2500psi and below, without having to have a high pressure tank tethered to our rifles. I am just not comfortable with holding an airgun containing 4500psi near me.... honestly, I could not afford the expenses of high pressure carbon tanks and associated paraphernalia. Perhaps, a lead coat on lighter inner core so we get our usual 18 grains just like a JSB pellet weight. Diabolo pellet design simply suffers limitation from long range accuracy.. because of its design.
 
I honestly don't think that concept is gonna work with 'normal' power levels. Might work fine in a custom high powered rifle, with a ridiculously low shot count, which means you have to shoot tethered indeed (we usually do it like that over here, on BR shoots).
No need for a carbon tank btw, steel scuba tanks are just fine, albeit heavier - anyway, that's clearly not the approach you want.

I tested the British Prometheus Piledriver pellets in .22 (well they were British, the rights and machinery were recently bought by H&N). They don't have the typical pointed bullet shape, as I guess that would be way too heavy, especially in the UK (12 foot pounds limit).



http://www.hn-sport.de/en/products/air-gun-pellets/hunting-and-field-target/piledriver.html

Tested them in my old Evanix AR-6 - not the most accurate airgun mind you, yet it has more than enough power. Shot tethered to the tank, at some 190 bar. Wasn't impressed by their accuracy at all, there's better pellets in that weight category.

Just one test though, and there's obviously so many variables. When shooting bullets/slugs in stead of diabolo shaped pellets, high power levels are a requirement though. Not sure if a boat tail design can be beneficial, look at this guy shooting cans at a quarter mile using bullets with a flat tail, from his custom Talon/Condor hybrid:


Obviously, the rifling in your barrel is also a critical characteristic. Theoretically, bullets shot from barrels meant for pellets (which require lower twist rates) won't perform well at all.




 
Spiraling often means you're shooting at too high speeds. The pellet going supersonic isn't an issue necessarily, when it goes below the speed of sound again it starts to spiral however. And keeping it supersonic isn't exactly easy...

I've shot pellets quite accurately at distances around 110 yards, and when it wasn't accurate, that was my fault (improper compensation for wind, for example), not the gun or pellet's. Shooting even further is also perfectly possible, given an accurate gun, haven't done it myself yet though.
 
"steeldreams"There has got to be a way to improve the Ballistic Coefficient of airgun projectiles. Right now, the maximum reliable long range my rifle I have seen so far is right about 70 yards with the diabolo pellet design. Beyond that, slow motion video analysis of pellet flight shows uncontrollable pellet spiral.

Spiral could be dirty bbl., wrong head size, damaged rifling at the muzzle or your gun just does not like that pellet. Since you mention the 2500 fill pressure I'm guessing you have a Gen2 Marauder in .177 or .22? For long range shooting you might give H&N Baracuda or Field Target Trophy a try as they are available in a range of head sizes in .177 and .22. Us .25 guys don't have any where near the selection the smaller bores have. I would try the heavier Baracuda as it would be one of the first for a long range pellet. If you are interested I think Chairgun has the BCs of various pellets.

 
Realistically, there is no practical advantage to firearm type boatail bullet designs at the slow speed airguns are likely to achieve. Ballistic advantage is gained by simply making the projectile longer, and the boatail does that, but the gains are very small for firearms at shorter (under 500 yds) ranges compared to flat based ones of equal length.