GECO · Hunting

GECO STAR 8x57 IS 10,4g

0.255BC (G1)

160.0gr10.37 g

816m/s2677 fps

3452J2546 ft·lb

Manufacturer	GECO
Calibre	8.22 mm (.324")
Bullet weight	160.0 gr · 10.37 g
Ballistic coefficient G1	0.255
Ballistic coefficient G7	not published
Drag model used	G1
Muzzle velocity	816.0 m/s · 2677 fps
Muzzle energy	3452 J · 2546 ft·lb
Sectional density	0.218
Form factor	i1 0.856
Category	Hunting
Source	GECO website 2026-07-02 (verified)

Reading these numbers

Only a G1 ballistic coefficient is published for this load, so BallisticApp solves it against the G1 drag table. G1 BC drifts with velocity — the figure below is valid near the muzzle and drops off as the bullet slows.

Muzzle energy of 3452 J (2546 ft·lb) is computed from the bullet weight and muzzle velocity above, not quoted from the catalogue. Sectional density 0.218 describes weight per unit of frontal area; divided by the ballistic coefficient it gives the form factor, which is how much drag the shape adds over the standard projectile.

Among the 44 loads of this bore diameter in the database, this one's G1 BC of 0.255 is higher than 20 of them.

Similar 8.22 mm (.324") loads

GECO STAR 8x57 IRS 10,4g160 gr · BC 0.251 · 836 m/s Norma ECOSTRIKE 8x57 JRS 10,4g160 gr · BC 0.177 · 800 m/s Norma ECOSTRIKE 8x57 JS 10,4g160 gr · BC 0.177 · 850 m/s Norma Ecostrike Silencer 8x57 JS 10.4 g160 gr · BC 0.177 · 825 m/s SAKO Rapid Expansion Series 8 x 57 IS 9.7 g / 150 gr150 gr · BC 0.330 · 815 m/s SAKO Rapid Expansion Series 8 x 57 IRS 11.3 g / 174 gr174 gr · BC 0.374 · 775 m/s

Turn this into a drop table for your rifle.

These figures are the bullet's starting point. What you actually dial depends on your rifle's zero, the air you're shooting in and the wind on the day — BallisticApp solves that on the phone, offline, using the same G1/G7 tables and this database.

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