HMR Ballistics

[peek-at]

Hi,

 

Ive just bought myself a pre-owned CZ452 Style 17hmr which has come with a Bushnell scope which has a plain crosshair. I'm used to scopes with mildots so I'm trying to get my head around bullet drop until the weather fairs up a bit and I can go out and practice.

 

I found a ballistics calculator on tinterweb and just wonder if the figures given actually translate to real life, So I would be interested if you guys think these figures sound about right

 

17g v-max 2550 fps scope height 1.75 100 yard zero

 

 

Drop (inches) Distance (yds)

 

1 130

2 145

3 155 (adult rabbits ear 3" long - could use as a reference)

4 165

5 175

6 185

7 193

8 200

9 205

10 210

11 215

12 220

13 225

14 230

15 235

16 240

 

[ste 2712]

good info on this page http://www.varmintal.com/17hmr.htm

but you will really need to go out and shoot paper at different ranges to see how your rifle shoots, the tables will only get you so far.

[wymberley]

The Infinity Sierra Suite says those figures are spot on and as you say, they'll need checking out in the field.

[kent]

With a 100yard zero its easy enough to call the trajectory to say 150-160 and you figures look about there. HOWEVER remember wind can and will effect both lateral and vertical displacement, on a HMR this is were the skill comes in at 100 yards a ten MPH full value side wind will shift you sideways about as much as a 160 yard shot drops your bullet strike point from a 100 yard zero. So at said 150-160 range I should be thinking twice as much about doping the wind as drop as a FV wind is likely to be the bigger correction and not a set constant through the peaks and troughs of its cycle. Don't believe wind cannot depress a bullet or lift it as it acts with or against the spin or blows up or down a contour.

 

The HMR is a fine flat shooting easy to shoot bunny bun on a good day, its the wind that normally throws a spanner in the works. Terminally things change a lot around 150-160 and some of the bunnies (sometimes) look like they have suffered heart failure until you skin them you don't find entry and exit points.

 

On trajectory the gun will shoot flatter at higher altitude than it will at sea level as pressure effects this in all guns (also the weather related air pressure)

Edited January 29, 2014 by kent

[Brad93]

Why not use clicks on the scope and write it on a little laminated card? Much more accurate

[Luckyshot]

Why not use clicks on the scope and write it on a little laminated card? Much more accurate

 

Shooting living creatures you don't normally have that much time.

[Mentalmac]

I tend to to aim higher if possible at a distance, so that if I miss it's a clean miss and not a wound, and that's all headshots.

 

The damage from a 17 HMR is fairly brutal and does a fair job of killing them, however body shots are usually rendered inedible all but for the rear legs and half the loins. Head all the way, and when it hits bone it's usually a neater job.

 

When I first got my HMR I went to my perm one afternoon and put some empty plastic milk bottles (1 ltr) with shoot and see targets attached to top to mimic a standing rabbit, and set them out at points I often see them at. I then put some rounds in each until knowing the correct drop etc (real life not what it tells you on chairgun or elsewhere) and jotted it down so I could review it that night. I use them as my markers and don't miss much now. Just a thought. :-)

[kent]

 

Shooting living creatures you don't normally have that much time.

 

You should when your laid waiting 150 yards away

[Bewsher500]

I tend to to aim higher if possible at a distance, so that if I miss it's a clean miss and not a wound, and that's all headshots.

 

I keep reading this about clean miss or clean hit

you might "clean miss" but you are just as likely to clip an ear, a jaw, clip the top of the skull etc etc

[team tractor]

 

You should when your laid waiting 150 yards away

Boom :)

[Dekers]

All the general charts are a guide at best, but can be useful, as others have said, do no rely on them and try specifically with your setup and ammo!

[sirgoldalot]

i like istrelok ballistics works well on 22lr and HMR

[dadioles]

Broadly speaking, you get a one inch drop every 10 yards once beyond the sweet flat spot.

 

That is why you need a laser range finder.

 

I certainly cannot judge distances that accurately and rather doubt that anyone else can either.

 

For rabbits I consider 150 yards to be pushing it a bit for reliable headshots and certainly no further unless pure pest control with body shots.

 

I get a one inch drop at 125 yards with a 100 yard zero, two inch drop at 140 yards and a shade under three inches at 150 yards. Four inches at 160 and five inches at 170.

 

My groups at 100 yards are reliably within a one inch circle but at 150 yards they have opened up to as much as two inches in less than perfect conditions. That is too much for reliable head shots but ok for straight forward pest control.

[kent]

The hardest bit is the wind is likely the biggest correction you will need to make at 100 yds and further with a HMR. Safe-siding the wind (ie aiming at the bunnies neck for a head , neck or chest shot helps some) and likewise with drop wait for the rabbit to stand or dope on the lowest range estimate and aim just under the back, it gives a little tolerance. Until you start getting silly with range the HMR with a good chosen zero gives you enough latitude if you can shoot to the required standard are half way decent at guessing the range and understand wind doping in the first place

[peek-at]

Tried zeroing the HMR in this morning and got myself annoyed as what seemed just a light wind was knocking the bullet all over the place.

Very frustrating, but realised that the wind had been shifting around and been gusting a little. Obviously enough to ****** things up.

I will have to try again on a still day but hopefully (i think) have it 'there or there abouts.'

 

(The ballistic chart led me to believe that the zero at 50yds would be zero at 100yds too. however, when I moved in from 100 to 50 and took another few shots, they were about a quarter inch low so I wont put too much faith in these charts.)

[kent]

Tried zeroing the HMR in this morning and got myself annoyed as what seemed just a light wind was knocking the bullet all over the place.

Very frustrating, but realised that the wind had been shifting around and been gusting a little. Obviously enough to ****** things up.

I will have to try again on a still day but hopefully (i think) have it 'there or there abouts.'

 

(The ballistic chart led me to believe that the zero at 50yds would be zero at 100yds too. however, when I moved in from 100 to 50 and took another few shots, they were about a quarter inch low so I wont put too much faith in these charts.)

 

When your down to detail you always need to shoot it. Pressure and wind reacting with contours will also effect were the bullet strikes up and down, don't forget this as will height above sea level. If this sound a little too much just consider that if you zeroed in the fens you would be about an inch high at 100 up here in the hills due to change in pressure . Best days to zero a HMR are with a light but very steady headwind as very light 2-3 mph gusts that might not be felt or detected at the firing point will still shift you approx. one inch at full value 90 degrees. at just 100 yards. True head on winds being nil value! Or find a tunnel range, if your crack on at shorter ranges without any left to right cross over of placement through those shorter ranges its odds on your base windage setting is crack on

In short it is very hard in practice to call the first cold clean bore shot with a HMR any better than MOA under field conditions.

[cal 7888]

or just cut the ******** and go to vortex's website on their LRBC (long range ballistics calculator) and it will do it for you in minutes, print you off a handheld drop chart and the points shown on a reticule (a vortex one)

[Bansk65]

i like istrelok ballistics works well on 22lr and HMR

I downloaded istrelok, haven't a clue how to use it, but i am as thick as monks spunk. I just want something user friendly !!

[Alan Maughan]

From the Winchester Ballistics Calculator

 

[kent]

Its not just as easy as that, you need a chroned velocity for your gun and the ammo and you need the air pressure and then you need to shoot it and record the results in different conditions. Its a guide, not a user manual. You still need to form "real word data"

[colin lad]

as kent is pointing out don't matter what it say's on a piece of paper you can't beat going out and shooting your gun and ammo and jotting down the actual data that your gun and ammo is giving,

just because it says on a bit of paper that you will get x amount of drop at said distance and x amount of drift,

you can't beat finding out for yourself

 

colin