Die richtige Munition wählen: Größe, Gewicht und warum Rundheit zählt

Ammo is the cheapest variable in the whole setup, and the one most people get wrong first. Too heavy and you lose speed and tire out. Too light and it will not hold a line in wind.

The three sizes worth knowing

Diameter	Weight	Best for
6 – 7 mm	Light	Learning. Easy to control, low fatigue over long sessions.
8 mm (5/16 in)	about 2.0 g	The balanced default for adult target shooting. Stable flight, cheap in bulk.
9.5 mm (3/8 in)	Heavier	Best all-round value. Fits nearly every frame.

The baseline setup

If you want one configuration to start from and adjust later: 8 mm steel with 0.5 mm bands. It is the combination much of the shooting community treats as a reference point, and it works across a wide range of frames.

Buy round ammo, not just cheap ammo

Steel ball bearings are graded for sphericity. Grade 100 or better is worth the small premium — roundness directly determines how consistently a ball leaves the pouch and holds its line. Irregular ammo will scatter your groups no matter how clean your release is, and you will spend weeks blaming your technique.

Matching ammo to bands

Heavier ammo needs more band to move it. Pairing 9.5 mm steel with light 0.5 mm bands wastes the ammo; pairing 6 mm with heavy 1.0 mm bands wastes the band and punishes your fork. Move the two together.

A rough rule: if the ammo feels like it is being thrown rather than driven, go thicker. If the draw is heavy but the ball is not noticeably faster, go lighter on the ammo before you go heavier on the band.

Before you order in bulk

Buy a small quantity of two sizes and shoot both at the same target, at the same distance, on the same day. The difference shows up within fifty shots, and you will have saved yourself a thousand rounds of the wrong thing.