Ballistics question for the experts.

[Jamie D Van Roekel]

Don’t pay attention to the middle hole it is a previous shot. There two groups of 3 plus the middle hole. The top group is 270 LRX the bottom group is 350TSX. I would like to be able to use the 350s for buff so if I move up a couple clicks the 270s will be just under 2 in. High and the 350s will be nearly dead on at 100 yards.

To my question. If the 350s are dead on at 100 have they crossed my line of site before they got there. I’m used to being a little high at 100 then they cross at 30-50 yards the again at around 200. I can’t rap my head around how it works if I’m low at 100. My scope is roughly 2 inches above bore.

Thanks for helping me visualize how this works.

 

[TucsonFX4]

My general expectation for most calibers, is about the top of the curve. You could input your data into a solver (4dof, strelock, whatever you use) and just play with the yards until you find the highest point. My guess is 100 will be close.

 

[mark-hunter]

Thanks for helping me visualize how this works.

Experience:
Most of rifles I tested, or zeroed: (calibers 30, and similar) have zero at 50 and approximate zero at 100.
This means zero the rifle at 50 meters, check it at 100, it will be zero again.
Then you can increase the range by playing with point blank range, keeping trajectory loop within size of vital zone of animal you hunt.
Example:
My 30-06 has +3cm at 50 meters, +6 cm at 100 meters, zero at 200 meters (about)
next reference: 375 HH has external ballistic similar to 30-06. Just to give you idea of similarities of various caliber trajectories

If you are negative at 50, you will be more negative at any further distance.
If you are positive till 50, it is just matter establishing the second zero and distance

Practical advice.
If you want exact reference, for your specific load, get following data of your cartridge:
Muzzle velocity (measure by chrono).
(or muzzle velocity by factory, reduce by 10-20 feet per second from declared value on the box)
Bullet weight (provided by factory reference, or by your scale)
Bullet BC, ballistic coefficient. (provided by factory on the box)
Exact distance of scope to muzzle. (measure)

Then go to ballistic calculator on line, suggest Hornady ballistic calculator (google this), enter above data for any distance and any zero, press enter and get calculated ballistic table
For example: try entering zero at 100, or zero at 200, etc, and get the idea of trajectory for any load you wish.
Then zero the rifle as per your preference.

 

[Tra3]

The 350s probably cross the zero line around 60 yards, depending on velocity.

If you have a modicum of curiosity about ballistics, then for a cheap few dollars you can get a ballistics app like Ballistics AE. It is easy to input data and get some helpful results.

I’ve been pondering a similar question, but with my .22 rifle. The subsonic ammo is fun to shoot because it is so quiet, but it is slower. I’ve had to figure out trajectory of the slow stuff and readjust my perceptions of where to aim at distance, without adjusting the scope since I use regular ammo to hunt.

 

[shootist~]

(yd)	Path (in)	Path (moa)	Drift (in)	Drift (moa)	Velocity (fps)	Energy (ft-lbs)	TOF (s)
200	-6.2	+3.0	-4.1	+1.9	1907.4	2827.2	0.290
175	-3.8	+2.1	-3.1	+1.7	1948.4	2950.2	0.251
150	-2.0	+1.3	-2.2	+1.4	1989.8	3076.9	0.213
125	-0.8	+0.6	-1.5	+1.2	2032.1	3209.0	0.175
100	-0.0	0	-1.0	+0.9	2074.6	3344.7	0.139
75	0.2	-0.3	-0.5	+0.7	2117.3	3483.9	0.103
50	-0.0	0	-0.2	+0.5	2160.8	3628.5	0.068
25	-0.7	+2.8	-0.1	+0.2	2205.1	3778.6	0.034
0	-1.9	0.0	-0.0	0.0	2250.0	3934.3

 

[shootist~]

Above is per the software I've used on my phone for 15 years or so. Actual POI at 50 yards needs to be verified as it will often be off a little depending on type of rest and how you hold your tounge.

350 TSX. BC .425. MV 2,250 fps. Sight hight 1.9". 100 yd zero " apprx 50 yd zero. Below line of sight almost every where but slightly above somewhere between 50 and 100.

 

[Tex .416]

The most reliable answer to the question is to go shoot a target at each distance. The targets tell the truth. Plus, practicing at different distances will train the brain on what to expect and how to react.

 

[mark-hunter]

The most reliable answer to the question is to go shoot a target at each distance. The targets tell the truth. Plus, practicing at different distances will train the brain on what to expect and how to react.

This is what I do after zeroing.
I zero at 200.
When happy with zeroing, I change target and put new target at 200.
Take one shot at 200.

Move the same paper target to 100. Take one shot at 100
Move same target at 50, Take one shot at 50.

Then I have a test target printed with 3 holes, I mark each hole by distance taken, and keep a target in a box of ammo, for reminder.