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Thread: Having a play with the rifle....CZ Varmint .17HMR just getting to grips....

  1. #1

    Smile Having a play with the rifle....CZ Varmint .17HMR just getting to grips....

    Got out this afternoon for a quick never seems an ideal time and the law of sod was doing its bit today as sooner had i got my stuff together than it lashed down and the wind got
    I manufacutred a quick portable target stand out of an old metal coat hanger and took my newly made shooting sticks with us.

    my first two shots were at 35 yards....just a quick check to make sure it was nearly there.

    happy it was still shooting ok, i moved it out to 100 yards. i kept the magnification at 12x and fired 3 shots. i could just see them at the top of the target...i was aiming for the centre.

    that was the first grouping of three within 3/4" - i was happy with that! i also noted that using the mil dots it appeared to be the next one up from for the next 3 shots i used that mil dot and aimed for the centre of the target.
    these three shots were just over 3/4" [1/4" high and 1 1/2" left of centre]

    i then decided to move it out to 125 yards. [a zero at 36 yards should also give a second zero at 122 yards if the calculator is right, but in my past tests it didn't seem to be that way]

    i got back to the rifle to find i had set the target too low to the ground, i couldnt see the bottom edge due to the grass, but i couldnt be bothered to walk out and lift it so i made do.....i fired off a few rounds [the 1 and 2 shot above and below the middle 3] before switching to 20x mag.
    i then aimed the next 2 shots again using the 1st mil dot at a point centre high where the blue ring meets the white , the grouping was only just over 1/4", it was about 1/4" low though.

    that was it for me though and i was happy with was still 3" high at 125 yards which i thought strange but will see what happens when i get a good day to test it. Throughout this the wind was blowing directly from behind me [may be why the round was so high at 122yards?], it was strong and gusting so i think my new rest will do. I may remove the rubber and replace it with some thin leather just to cushion the rifle. the rubber did stop you adjusting it easily as it really gripped it too tightly.

    anyway hope this makes sense....any comment welcomed....

  2. #2
    I shoot a lot of 17HMR and leave it zeroed at 100 Yards. Get your rifle on a rest and give it a try on still morning. Do you have parallax adjustments on that scope of yours?~Muir

  3. #3
    hi...thanks muir...yes i do have PA adjustment. i do use it. i had it on my .22lr rimmie till i got this and it worked fine out to 120 yards [on a good day]. the BRC program gives me other results and to be honest i didnt expect the results i am getting. i am hoping for a still day and i will go out and set up 5 or 6 targets at set ranges and see what sort of arc this is giving me!!?? a zero at 36 yards would suit me if it was only an inch high/low out to 140 yards but when i try to shoot this it is always a good 2.5" high betwen 80 yards and 122 yards???
    it doesnt look as if we will have a still day for a while now....will have to stock up on


  4. #4
    What ballistic coefficient are you assigning the bullet? What weight? 17 or 20 grain??~Muir

  5. #5
    hi....17, not sure what the ballistic coefficient is...i am just using the preprogrammed data in the BRC program....

    centre of scope is about 2" high of bore...

    Last edited by TokaS; 06-04-2010 at 19:18.

  6. #6
    It's hard to get an accurate ballistic picture without knowing the ballistic coefficient. The ballistic coefficient (or "BC") is a numerical designation given to a projectile that denotes its relative ability to slip through the air. a BC of "1.00" is, for this argument, the perfect projectile. All others are less. The BC of the 17 grain bullet is (if I remember right) .122 at sea level at 59F degrees. Speed of 2550 fps was used.

    I generated this chart using default altitude and temp settings but it will be close.~Muir

    Velocity: 2550
    Target Distance: 100
    Scope Height: 1.500
    Temperature: 70
    Altitude: 500

    Ballistic Data
    Range Elevation Velocity Energy ETA Drop Max Y 10mph Wind Deflect
    0 yds -1.50 in 2550 fps 245 fpe 0.000 sec 0.00 in -1.50 in 0.00 in
    25 yds -0.49 in 2380 fps 214 fpe 0.030 sec 0.17 in -0.56 in 0.16 in
    50 yds 0.13 in 2217 fps 186 fpe 0.063 sec 0.73 in -0.41 in 0.75 in
    75 yds 0.32 in 2060 fps 160 fpe 0.098 sec 1.74 in -0.13 in 1.76 in
    100 yds 0.00 in 1909 fps 138 fpe 0.136 sec 3.24 in 0.30 in 3.18 in
    125 yds -0.93 in 1767 fps 118 fpe 0.177 sec 5.35 in 0.92 in 5.22 in
    150 yds -2.58 in 1633 fps 101 fpe 0.221 sec 8.19 in 1.78 in 7.88 in
    175 yds -5.00 in 1506 fps 86 fpe 0.269 sec 11.79 in 2.91 in 11.06 in
    200 yds -8.43 in 1391 fps 73 fpe 0.321 sec 16.40 in 4.40 in 15.01 in

  7. #7
    i played around with the BRC program and the only thing that gets the same practical results as i am getting is if the round is being fired at 3040fps [not 2550fps]??? i am on the lookout for lower mounts but all the medium height ones i have found up here are a couple of mm too low and the scope housig hits the barrel before it is seated properly...


  8. #8
    I'd scrap the BRC data if it back-feeds 3040 fps. No chance of that happening! My data is fairly accurate.~Muir

  9. #9
    well...went and had another play today. Wind light, sun out, ground rock hard and unomfortable...layed out markers with a tape measure so distances quite accurate today.
    First 3 shots at 35 meters.
    ,so altered it till it was near zero.... A bit sloppy really but i was more interested in the 100/122 marks. So from this on i went out to 100 meters..., about 2" high and 2.2" left [poi was the lower right cross].
    So i started to bring it back over... and then decided to try out to 122 meters.
    ..seemed a lot more like it with the height...i managed to bring the grouping over to the right [cant find the pic for that...] and did a couple of shots at 80m, by now i was begining to sweat with the walking back and forth and i was running out of time [always the case when i need to be],back to 50m and this and finally back to 35m . then to tidy up and go...

    still it should have been zeroed at 122m but it is firing about 1" high [i can live with that]. i do think it is my firing of the rifle that is throwing it high and i hope with practice i can sort that. these shots were taken off my attached bipod/prone. It will need a clean now and i will see if that affects the group, i may even try a diffeent ammo to see if it tightens anything up but want to sort my firing first....


  10. #10
    My mate & I found the 17grain totally useless in both his Sako & my CZ, similar to the groups you posted, 20 grain in his Sako are one hole @ 100, my CZ gives a little less accuracy, but will still poke out bunny eyes @100. Steve.
    (The Unspeakable In Pursuit Of The Uneatable.) " If I can help, I will help!." Former S.A.C.S. member!

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