Hornady · Pistol

17 HMR® 15.5 gr NTX® Varmint Express® Rimfire

0.115BC (G1)

15.5gr1.00 g

770m/s2525 fps

297J219 ft·lb

Manufacturer	Hornady
Calibre	4.37 mm (.172")
Bullet weight	15.5 gr · 1.00 g
Ballistic coefficient G1	0.115
Ballistic coefficient G7	not published
Drag model used	G1
Muzzle velocity	769.6 m/s · 2525 fps
Muzzle energy	297 J · 219 ft·lb
Sectional density	0.075
Form factor	i1 0.650
Category	Pistol
Source	Hornady 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 297 J (219 ft·lb) is computed from the bullet weight and muzzle velocity above, not quoted from the catalogue. Sectional density 0.075 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 19 loads of this bore diameter in the database, this one's G1 BC of 0.115 is higher than 4 of them.

Similar 4.37 mm (.172") loads

TNT Green, 17 HMR, 16 Grain, Speer TNT Green Hollow Point, 2500 fps16 gr · BC 0.090 · 762 m/s A17, 17 HMR, 17 Grain, Tipped Varmint, 2650 fps17 gr · BC 0.128 · 808 m/s A17, 17 HMR, 17 Grain, Tipped Varmint, 2650 fps [6-950CC]17 gr · BC 0.128 · 808 m/s TNT, 17 HMR, 17 Grain, Jacketed Hollow Point, 2550 fps17 gr · BC 0.100 · 777 m/s V-Max, 17 HMR, 17 Grain, V-Max®, 2550 fps17 gr · BC 0.128 · 777 m/s VNT™, 17 HMR, 17 Grain, VNT, 2650 fps17 gr · BC 0.125 · 808 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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