.17 HMR General Ballistics Discussion:
The .17 HMR stays supersonic beyond ~350yds so going subsonic is not much concern. The 17gr bullet is more popular than the 20gr bullet. Typically, same shape bullets with higher SD have higher BC, but Hornady lists the same BC for both bullets. At 200yds, the heavier bullet only has 4% more energy which doesn’t seem like much advantage for an additional ~1.5″ of drop. The heavier bullet should be less affected by the wind.
The next chart compares zeroing options for .17 HMR 17gr and 20gr. Again, it’s convenient to use a Zero Offset at a desired midrange for zeroing. The offset prevents the POA from being shot away while shooting the group. The amount of offset should be ~50% of typical target size. Practical .17 HMR zeroing choices are 0.5″-1.5″ high at 100yds.
- For important shorter ranges, the scope tube height above the barrel influences the calculations quite a bit so make sure you use your appropriate value.
- Benefits to setting your zero some amount high at the midrange:
- Your POA does not get blown away while you are shooting your group.
- For hunting, the amount high you select is related to your target size such that it creates an extended range in which you can point and shoot and still be on target.
- The bigger Zero Offset you can use, the wider range your POI offset will work, plus the less MOA adjustment required at longer ranges.
Optics Discussion for .17 HMR
The .17 HMR is capable of 250-300yds. Target sizes associated with its ~60 ft-lbs of energy at that range will be 3″-6″. Comfortable zoom power for that size target at that range is 20-24x. With such small targets, adjustable parallax is important to maintain accuracy. The OptiCo 6-24x50mm delivers all of those features. The FFP reticle is 0.17 moa so at ~300yds it will be ~0.5″ wide on typical 3″-6″ size targets.