I'm going to participate in a match that includes some long(ish)-range shooting (200 and 475 m = 220 and 520 yards). I'll only get 5 sighting shots per distance, and I only have a 100 m (110 yards) range available to sight in my rifles before the match, so I'll have to do some maths.
It would be great if you could check if my approach is reasonable, and help me out with some details.
Let's take the 520 yd match as an example. I am using the ballistic calculator from gundata.org: http://gundata.org/ballistic-calculator/
I set "zero range" to 520 yd and calculated the "drop" of the bullet at 110 yd. It gives me a "drop" (i.e. rise) of about +11.8" at 110 yd.
Now I should be able to sight in my rifle for the 520 yd match using the 110 yd shooting range by making sure that my rifle shoots 11.8" above point of aim – correct?
As for the details:
For the 520 yd match, I will be using a scoped Izhmash Tigr rifle chambered in .308 Win (22 ¼" barrel; 3.3" sight height over bore; shooting S&B 147gr FMJ factory ammo).
Gundata.org gives a ballistic coefficient of 0.409 for the S&B bullet, and I estimate that muzzle velocity is around 2800 fps. According to the ballistic calculator, this results in a 11.8" rise at 110 yd, as mentioned above.
I'd like to compete in the 220 yd match with a Swedish Mauser m/1896 chambered in 6.5x55 (29.1“ barrel, 0.7" sight height over bore, shooting S&B 140 gr FMJ factory ammo).
According to gundata.org, the bullet's ballistic coefficient is 0.465, and muzzle velocity for S&B 140 gr FMJ ammo is 2582 fps. This should result in a 3.2" rise at 110 yd.
Some additional, not so decisive questions:
- Do you think 2582 fps is a realistic muzzle velocity for a 147gr FMJ bullet out of an M96 Swedish Mauser?
The S&B homepage specifies that this velocity is achieved trough a 24" barrel (a little longer than an M38 barrel). Might the barrel of the M96, which is more than 5 inches longer, lead to a significantly higher muzzle velocity?
- Am I correct in assuming that the G1 drag model is the one best suited to calculate the trajectory of both the .308 and 6.5x55 FMJ bullets used by S&B?
Thanks for your help.
And now, after so many numbers, it's time for some pictures:
It would be great if you could check if my approach is reasonable, and help me out with some details.
Let's take the 520 yd match as an example. I am using the ballistic calculator from gundata.org: http://gundata.org/ballistic-calculator/
I set "zero range" to 520 yd and calculated the "drop" of the bullet at 110 yd. It gives me a "drop" (i.e. rise) of about +11.8" at 110 yd.
Now I should be able to sight in my rifle for the 520 yd match using the 110 yd shooting range by making sure that my rifle shoots 11.8" above point of aim – correct?
As for the details:
For the 520 yd match, I will be using a scoped Izhmash Tigr rifle chambered in .308 Win (22 ¼" barrel; 3.3" sight height over bore; shooting S&B 147gr FMJ factory ammo).
Gundata.org gives a ballistic coefficient of 0.409 for the S&B bullet, and I estimate that muzzle velocity is around 2800 fps. According to the ballistic calculator, this results in a 11.8" rise at 110 yd, as mentioned above.
I'd like to compete in the 220 yd match with a Swedish Mauser m/1896 chambered in 6.5x55 (29.1“ barrel, 0.7" sight height over bore, shooting S&B 140 gr FMJ factory ammo).
According to gundata.org, the bullet's ballistic coefficient is 0.465, and muzzle velocity for S&B 140 gr FMJ ammo is 2582 fps. This should result in a 3.2" rise at 110 yd.
Some additional, not so decisive questions:
- Do you think 2582 fps is a realistic muzzle velocity for a 147gr FMJ bullet out of an M96 Swedish Mauser?
The S&B homepage specifies that this velocity is achieved trough a 24" barrel (a little longer than an M38 barrel). Might the barrel of the M96, which is more than 5 inches longer, lead to a significantly higher muzzle velocity?
- Am I correct in assuming that the G1 drag model is the one best suited to calculate the trajectory of both the .308 and 6.5x55 FMJ bullets used by S&B?
Thanks for your help.
And now, after so many numbers, it's time for some pictures: