Range Report Explain the Point Mass Ballistics Solver to me

[kraigWY]

I just got Bryan Litz's book which came with the Point Mass Ballistic Solver.

OK I haven't totaly read the book, and its too cold for my old bones to go out and shoot long distance right now (I'm a wimp) so I desided, in playing with the Balisstic program, I'll use knowns. To Wit: My Super Match M1A that I have been shooting for over 30 years, most of that with the SMK 168 going at a MV of 2600 fps. Now in 30 years of shooting this rifle in high power, and the above load, I know that from 200 to 300 I come up 3 MOA, and from 300 to 600 I come up another 9 MOA. I still have a stack of score books, and except for a bit of changes for light, etc which is no more then 1 minute either way, my score books confirm this.

So I plug in the numbers into the ballistic program and ................no where close. From 2-300 the program calls for 3.87 inches.........ok not bad........BUT..... from 300 to 600 it calls for a 15.5 moa change.......that would put me over the target frame.

Where am I going wrong. I've played with Ballistic programs before they would at least get you on target. This one wont. I hate to see what happens if I tried it at 1000 yards.

So whats happening? I personally liked Hatcher's Ideals of building Ballistic tables, they match what is acutally happening on the range with my rifle. I'll give Mr. Litz the benifit of the doubt and finish his book, hoping for better results.

 

[MitchAlsup]

Re: Explain the Point Mass Ballistics Solver to me

Just a guess:

I used JBM ballistics: Sierra 168 SMK (Litz) at 2600

200-300 3.1 inches/100yards 3.0 MoA
300-600 13.0 inches/100yards 12.4 MoA
200-600 16.1 inches/100yards 15.4 MoA
400-600 9.2 inches/100yards 8.9 MoA

200-300 agrees with you 3 MoA
200-600 agress with book 15.4 MoA
400-600 agrees with what you are stating as 300-600 9 MoA

Are you sure the book is using 15.5 for the 300-600? where is looks to me like it should be using this for 200-600.

 

[Lindy]

Re: Explain the Point Mass Ballistics Solver to me

I think you are misremembering something. All of that "come up from" is confusing.

Most .308s I've seen are around 15.5 - 16 MOA <span style="font-style: italic">total</span> at 600.

And you didn't note how many MOA you can up from 100 to 200. Most .308s are around 2 MOA up from 100.

With what you say, that would put you at 14 MOA total at 600. I've never seen one that fast at 600, and certainly not out of a M1A/M14. Might happen at a high altitude.

What atmospheric parameters, especially pressure & altitude, are you assuming for your historic data?

The program defaults to an ICAO standard day.

And I've shot Bryan's data for a 175 SMK at my chronographed muzzle velocity out to 1000 yards. It works, within 0.1 mil.

 

[kraigWY]

Re: Explain the Point Mass Ballistics Solver to me

OK I just checked some older score books

My average was, from the bottom of the sight base:

UP 14 for 200 yards
Up 17 for 300 yards
Up 28 for 600 yards......11 up from 300 instead of 9

This was all with LC 852. I dont remember the elevation but this was the average from FT Richardson AK, Camp Robertson AR, Ft Lewis Washington, K bay Hawaii, and 29 Palms CA.

Like I said, I need to study Litz book some more. So far the Lee Shooting program comes closer to what my guns shoot.

 

[Lindy]

Re: Explain the Point Mass Ballistics Solver to me

OK - I don't know what your sight reference is.

How many total MOA at 600 yards?

 

[kraigWY]

Re: Explain the Point Mass Ballistics Solver to me

I'm using irons of course, taking a 6-O-Clock hold. My 600 zero is 11 full min. clicks up from my 300 yard zero.

Here is the gun:

 

[Lindy]

Re: Explain the Point Mass Ballistics Solver to me

OK. Well, most .308s are up 5 minutes at 300, so up 11 will put you at 16 - which is within a half MOA of what the software predicts. To coin a phrase, "Where's the beef?"

 

[BryanLitz]

Re: Explain the Point Mass Ballistics Solver to me

The confusion may be coming from the claim: "I'm using irons of course, taking a 6-O-Clock hold."

A 6 O'clock hold means the front sight post is positioned at the bottom of the aiming black (circle). Now I'm not sure of the dimensions of the circle at each range, but I know it's bigger at longer range. In other words, a 6 O'clock hold on the 200 yard target might mean you're hitting 2" above post at that range, but at 600 yards where the black is much larger in diameter, positioning the post at 6 O'clock means you're POI is more like 12" to 18" above the post.

Could that be the culprit?

 

[Lindy]

Re: Explain the Point Mass Ballistics Solver to me

Good thinking. The current MR1 target used in XTC shooting at 600 yards has a 36" black. Half of that, at 600, is almost 3 minutes.

 

[kraigWY]

Re: Explain the Point Mass Ballistics Solver to me

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">A 6 O'clock hold means the front sight post is positioned at the bottom of the aiming black (circle). </div></div>

WELL POOPIE.............thats it

Nothing like making an ass out of my self.

 

[Lindy]

Re: Explain the Point Mass Ballistics Solver to me

Don't worry about it, Kraig. If I haven't done that a couple of times in a given day, it's because I didn't <span style="font-style: italic">do</span> anything.