Recent content by Ballisticboy

Pellets are not drag stabilized and never have been. They are stabilized by the lateral moments about the CG produced by the flare, not the drag, which produces essentially zero moment about the CG. https://www.airgunnation.com/threads/aerodynamic-stability-of-pellets.1276895/ Spiralling is...

They may look super cool, but it is unlikely that the airflow will see the boat tail, as it has to turn through far too big an angle to follow the slug base contour. BC will be better than if the slug did not have the boat tail on the back of it, but only because the sectional density has...

At subsonic speeds, the nose drag is a very small component of the total drag once you have got an ogive nose of a reasonable length, say 1 calibre maximum. Going longer will give very little reduction in form drag, but may even increase skin friction drag from the greater surface area. The...

There are only three possibilities if the hole in the back has been increased in size:- 1 The new pellet is lighter than the old design, which will change the flight behaviour and BC of the pellet compared to the old design due to the change in sectional density 2 AEA have managed to...

The difference in the thickness of the skirt will have little to no effect on the pellet base drag. It will move the centre of gravity which would change the aerodynamic stability which, if already marginal, may lead to larger groups or needing a different twist rate for optimization.

Can I suggest that instead of shooting 3 groups of old and then 3 groups of new, you try 1 group of old followed by 1 group of new, then 1 group of old and 1 group of new etc. as this will help to keep the same conditions for both types of pellet. It may not make any difference, but it may just...

Not with the right program. ;)

I tried something different for the stability factor. I modelled the projectile with a cylindrical base, i.e. no boat tail. The results are below. M Sg Sd State sd*(2-sd)*sg 0.3 1.65 0.825 Stable 1.6 0.5 1.452 0.705 Stable 1.326 0.6 1.445 0.576 Stable 1.185 0.7 1.388 0.435 Unstable...

I didn't say it couldn't be shot from a 16-inch twist, I said it will start off being unstable, but the level of instability is small so it will soon gain stability as it slows down. Also, if the slug is a good fit in your gun and leaves the barrel with very little yaw or very small yaw rates...

Neither Strelok nor the Element ballistic app have the capability to accurately calculate the gyroscopic stability factor. To do it properly, you have to have the moments of inertia, and the aerodynamic pitching moment coefficients at all Mach numbers. Software like McGyro and the Kolbe...

Using the photos in this thread, I did a physical and aerodynamic analysis of these slugs. As they are solid, they are relatively simple to analyse for the physical properties. These are the results I got. Mass 2.667 grams which is 41.1 grains Ix 9.232E-09 Kg Metres squared Iy...

It is not necessarily 10%, that only applies to goods made in the UK. If the goods have actually been made in China, as many spares are, then the tariff rates are those applying to China even if you have bought them from the UK. So all their goods will have different tariff rates depending on...

Looks like they have reduced the boat tail angle to be much closer to what I was saying it should be, compared to the design shown earlier in this thread.

The problem with cleaning the barrel, then leading it up etc. is that by the time you have done that, the atmospheric conditions will have changed, and you will not be comparing like for like. If you are testing indoors then there is no problem, but outdoors the wind speed and direction...

These are the lightest I have seen. https://www.daileisure.co.uk/kvintor-blik-flash-bang-pellets-177 I measured the BC for them years ago, it came out as .0025. They made a nice bang if you managed to hit what you were aiming at.