Optimal trajectory setting - please explain

[Outdoorsman12b]

Can someone please explain the theory behind setting the optimal trajectory setting? I have watched the video a few times. The video implies to use about 2 MRAD in optimal field of fire and then aim short or long for a faster firing solution. I don’t have a thlr reticle but it seams I could apply this to the LRHS reticle.

 

[Rich M]

Is that like maximum point blank range? Most guns can shoot about 300 as point blank range.

 

[Wapiti1]

If you have a MIL or MOA reticle with marks above and below the crosshair, you use them to compensate for trajectory instead of dialing every shot.

An example would be to zero the center crosshair, or dot at say 500 yards. If you shoot at something at 100, you use the hash marks above the cross hair and hold low however many MIL or MOA your trajectory says to.

If you shoot farther than 500, you will hold high on the reticle and use the lower hash marks for trajectory compensation.

Its just a way of using the entire reticle for range compensation instead of only the center or only the portion below the cross hair.

There are some caveats. Field flatness of the optics can make the reticle inaccurate as you get to the edge and parallax becomes critical if you are using the reticle off center to line of sight. So, it works best if you limit how far off center you go.

There may be more to it, but that is how I understand their system to work.

Jeremy

 

[hereinaz]

Sounds like its about mashing "maximum point blank range" "danger space" and holdover or under into a "quick system". I didn't watch it...

All I need to know is between 0 and X yards, the bullet will hit a 6 inch circle (my maximum point blank zero. Beyond that, I range and glance at a dope sheet and hold or dial. If you learn your dope numbers from 300 to 500 yards in 50 yard increments, you can very fast shoot. Simple is better and the information is more useful, IMO.

I got to learn and talk shooting with instructors about what they did in deployments and would use in hunting (yes I dropped the sniper reference, LOL). They would always use a 100 yard zero and dial on the MPB zero elevation if they felt like they might need a quick shot of unknown distance, but still inside 300. Anything beyond that MPB zero, they would range and hold or dial. You don't need to get wrapped up into a "system". Learn the dope for your gun and shoot it.

Now, that's not to say there aren't other systems out there that you can learn and master, but I am lazy and get dumb when the shot matters, so I like simple.

 

[Rich M]

@Wapiti1, Thanks for the explanation.

I can see the hash marks above being handy. So, you zero center for say 400 yds, close in shots, use above hashes, further use the ones below it. Just need to be consistent - seems reasonable.

I was raised with max point blank range (this was before dialing or BDC scopes were common) - had my 3006 w 2900 fps 150 gr pointed soft points a couple inches high at 250 and good to 350 without any trouble - could stretch it to 400 without much thought.

 

[hereinaz]

@Wapiti1, Thanks for the explanation.

I can see the hash marks above being handy. So, you zero center for say 400 yds, close in shots, use above hashes, further use the ones below it. Just need to be consistent - seems reasonable.

I was raised with max point blank range (this was before dialing or BDC scopes were common) - had my 3006 w 2900 fps 150 gr pointed soft points a couple inches high at 250 and good to 350 without any trouble - could stretch it to 400 without much thought.

Agreed, MPBR out to 350 and holdovers out to 400 and 500 is pretty simple to memorize and use without thought.

Either system, you have to memorize holds. I think just learning only holdovers as you go out is better. Its one direction in the reticle.

I don't see how zeroing further out for hold unders in close and hold overs further out makes it any simpler.

 

[Rich M]

Agreed, MPBR out to 350 and holdovers out to 400 and 500 is pretty simple to memorize and use without thought.

Either system, you have to memorize holds. I think just learning only holdovers as you go out is better. Its one direction in the reticle.

I don't see how zeroing further out for hold unders in close and hold overs further out makes it any simpler.

I agree with the memorization - I could not go to a scope with all kinds of lines and call it easier. I do own a BDC scope but it only has 3 hashes below the +. The other stuff is more complicated than I want to learn/relearn at this point.

 

[Wapiti1]

Pride Fowler had a couple of scopes that worked this way and Zeiss did as well when they used that reticle design. On the PF scope, the center crosshair was at 400 meters with 100, 200, and 300 marked above. Below was 500 through 900 or 1000. These were calibrated reticles for .308 military loads. Once you got used to it, they were very fast and had good windage hashes for each range as well.

Point blank range is fine if you keep it reasonable. Steep shots in the mountains will mess you up, though, and holding low in those situations is a lot easier for me if I have a hash mark to focus on. Rather than just guessing how low.

Lot's of ways to skin that cat.

Jeremy

 

[Outdoorsman12b]

Thanks for replies so far all. To dive a bit deeper into what I was looking for there is an implied theory here that trajectories are similar across ballistic tables so it would appear that a common firing solution is being applied.

How is the optimal range determined?
What is the rule of thumb for using the holds within the 2 mil radius referenced?

 

[hereinaz]

Ballistic curve for elevation is 100% dependent on BC and Velocity (factoring out aerodynamic jump which doesn't matter much at shorter ranges). Bullet weight doesn't matter.

Two bullets of 100 grain and 200 grain have the same drop if the BC and muzzle velocity is the same. Two bullets with the same BC, but one fired slower drops faster. Two same velocity bullets but different BC, the lower BC drops faster.

So it varies, though you can draw some comparisons, if velocity and bc on two bullets are different the ballistic curves continue to diverge more and more the further you go.

But velocity matter more than BC in the first 500 yards for drop, because the rate of decay increases as a bullet slows. That's why the curve goes from "flat" to rainbow. The first 500 the decay is far less than the second 500 and even less than the third 500 yards.

Go to JBM Ballistics online and plug in two different loads you shoot and look at the drop out to whatever range you shoot. It is fun to compare.

But, similar velocity bullets will be very close out to 400 and 500 even if the BC varies a lot, compared to similar BC bullets with bigger velocity variation.

Its why "barrel burners" are always flat regardless of BC. And, lighter bullets can shoot "flatter" than heavier/higher BC bullets in the same caliber.

Its why my 180 vld at 3050 fps is better out to 900 yards than a higher BC 195 bullet. But, at some point past that the 195 and its higher BC starts to beat the 180. Its why copper solids with high BC and velocity are "better" than heavier lead bullets with lower BC.

 

[PNWGATOR]

@THLR would be your best resource to discuss the virtues of his reticle.
I would love this reticle in a NF or Bushnell or SWFA.

 

[Outdoorsman12b]

@THLR would be your best resource to discuss the virtues of his reticle.
I would love this reticle in a NF or Bushnell or SWFA.

Ah cool didn’t realize he was a RS member. This probably isn’t a long range forum post now that i think about it as we are talking about within 500 meters for this to work.

 

[THLR]

"Optimal trajectory setting" in the context of that film is with regards to the area you want to shoot into + reaction time.

Example:
Promising clearcut measures 450 to 720.
Line up the turret marks (and your uniques ballistics whatever that is) to best match that area.

I would set my own turret zero (center aim) to 580.
That places AIM SHORT at 490 and AIM LONG at 660.

So with the exception of the far edge of the clearcut, I can now eyeball range and shoot with a high degree of precision and have a response time that measures single digit seconds (timed from taking the rifle).
For a target far egde I just hold top or dial to range.

So "Optimal trajectory setting" in this context deals with workflow and time. Focus on target, engage at first opportunity. The application is mostly military. Most hunters will not be comfortable with shooting like this.

 

[hereinaz]

"Optimal trajectory setting" in the context of that film is with regards to the area you want to shoot into + reaction time.

Example:
Promising clearcut measures 450 to 720.
Line up the turret marks (and your uniques ballistics whatever that is) to best match that area.

I would set my own turret zero (center aim) to 580.
That places AIM SHORT at 490 and AIM LONG at 660.

So with the exception of the far edge of the clearcut, I can now eyeball range and shoot with a high degree of precision and have a response time that measures single digit seconds (timed from taking the rifle).
For a target far egde I just hold top or dial to range.

So "Optimal trajectory setting" in this context deals with workflow and time. Focus on target, engage at first opportunity. The application is mostly military. Most hunters will not be comfortable with shooting like this.

You make a lot of cool videos and good stuff. I watched a lot before, but haven't for a while.

It looks like you create a custom turret for each rifle to use the system? Is that right?

 

[Outdoorsman12b]

"Optimal trajectory setting" in the context of that film is with regards to the area you want to shoot into + reaction time.

Example:
Promising clearcut measures 450 to 720.
Line up the turret marks (and your uniques ballistics whatever that is) to best match that area.

I would set my own turret zero (center aim) to 580.
That places AIM SHORT at 490 and AIM LONG at 660.

So with the exception of the far edge of the clearcut, I can now eyeball range and shoot with a high degree of precision and have a response time that measures single digit seconds (timed from taking the rifle).
For a target far egde I just hold top or dial to range.

So "Optimal trajectory setting" in this context deals with workflow and time. Focus on target, engage at first opportunity. The application is mostly military. Most hunters will not be comfortable with shooting like this.

I can absolutely see the application here for hunting especially when:

A) hunting a cutline where the shot opportunity is going to be short and it is unknown where the animal will present itself.
B) a first round strike or miss is not optimal and the animal progresses away from known distance to another distance before pausing for another shot opportunity.

I have tried to find some information on the THLR reticle substensions but have not been successful. From what I can tell the box is 1 mil and the aim short and long is 1 mil from the zero aim point. If I am correct that would mean the hash marks in between aim long and short are in .2 mil increments?

Putting this into application with my 6.5 147 eldm with the same example you have outlined I get the same distances you have referenced in your example with 1 MIL up and down. The gap is 32 inches (short) on the bottom end and 36 (long) at the top end.

Can you explain more about how the trajectory solves these gaps and how you quickly decide which hold point to use within the aim short and long?

For reference I am trying to adapt this technique into using the reticle I currently have with .5 mil increments.

 

[hereinaz]

Curious myself. If 400 is 1.5 mil and 600 is 3.0 mil on my rifle. How do I calculate the center hold for that clearing? Based on yardage or middle of drop?

Normally, I would solve the problem with my reticle by dialing 1.5 for 400 and hold over another 1.5 for 600. I could keep the 500 holdover of .7 in my mind and "fudge" a guestimate for shots between. The difference in drop between 400 and 600 is 44 inches and between 500 and 550 is 12 inches. So, if I used 1.0 holdover for 550ish, I will be close to 525 to 565. That's the same except you dial to the middle of the clearing and I would dial to the closest edge.

Not sure mathematically the numbers are there for guessing. Distances are hard to judge and deer vitals don't leave a lot of room for all the possible errors it seems.

What size target can you hit with acceptable rates using the system?
What might the middle dial offer differently?

I can see value for some purposes. On man sized targets, the error in elevation gets absorbed in the longer torso for military purposes. But for hunting, the acceptable error is too high for me unless I am missing something.

Thomas, you have any other videos or resources to look at? I know you may have answered it elsewhere.

 

[Outdoorsman12b]

Curious myself. If 400 is 1.5 mil and 600 is 3.0 mil on my rifle. How do I calculate the center hold for that clearing? Based on yardage or middle of drop?

Normally, I would solve the problem with my reticle by dialing 1.5 for 400 and hold over another 1.5 for 600. I could keep the 500 holdover of .7 in my mind and "fudge" a guestimate for shots between. The difference in drop between 400 and 600 is 44 inches and between 500 and 550 is 12 inches. So, if I used 1.0 holdover for 550ish, I will be close to 525 to 565. That's the same except you dial to the middle of the clearing and I would dial to the closest edge.

Not sure mathematically the numbers are there for guessing. Distances are hard to judge and deer vitals don't leave a lot of room for all the possible errors it seems.

What size target can you hit with acceptable rates using the system?
What might the middle dial offer differently?

I can see value for some purposes. On man sized targets, the error in elevation gets absorbed in the longer torso for military purposes. But for hunting, the acceptable error is too high for me unless I am missing something.

Thomas, you have any other videos or resources to look at? I know you may have answered it elsewhere.

Thinking about this more now and maybe you just have to limit the technique within your acceptable size hit zone. So using a deer with 8-10 inch vitals you would want to keep this where you could acceptably pick a hold that would yield that result however your reticle is configured. In my case that might mean zeroing at 440 yards. If I was to shoot anything from 330-375 and 375-420 I could hold the animal in a .5 mil bracket and score a hit, after that is center hold and so on to the aim long POA. This may not be as fast as with the box design reticle to make the decision (which I don't understand at the moment) but with a range it could certainly speed process up to getting a shot opportunity instead of establishing a dial correction for a center hold.

 

[hereinaz]

Thinking about this more now and maybe you just have to limit the technique within your acceptable size hit zone. So using a deer with 8-10 inch vitals you would want to keep this where you could acceptably pick a hold that would yield that result however your reticle is configured. In my case that might mean zeroing at 440 yards. If I was to shoot anything from 330-375 and 375-420 I could hold the animal in a .5 mil bracket and score a hit, after that is center hold and so on to the aim long POA. This may not be as fast as with the box design reticle to make the decision (which I don't understand at the moment) but with a range it could certainly speed process up to getting a shot opportunity instead of establishing a dial correction for a center hold.

I am curious, and like to learn methods. Its cool the way he uses his ballistic knowledge to create and work a system. But, rubber hits the road is where I land.

I have gone through the exercise myself, thinking it through as you are exploring now, and thinking through where the system, or one approximating it would be effective. I can't see any benefit of zeroing at 440 yards and using the system for hunting. Here is an explanation of why I hold that opinion.

I and many others have come to the conclusion to zero at 100, dial on MPB zero of the rifle if the need might arise, and dial if it is further.

When it comes to shooting fast for hunting, I just can't find a system accurate enough and faster than a rangefinder that gives my my dope, like the Sig 2400 bdx paired with my Garmin 701. I can range, dial and shoot so fast I can't believe there is anything else needed. Anything faster is going to be a VERY hurried shot. Other guys have dope cards or equally fast ways to get the dope once they have a range. I know some who have shot their rifle so much they practically have it memorized.

Shooters in practical rifle matches have the ability to range the animal and shoot with a 3 mil holdover to 600 yards in seconds if they already have their position built and have had time to observe and make a wind call speed. Building a position and reading wind takes far longer than ranging and shooting.

One question with the practical application of the reticle and system to hunting (which is not a criticism of the system or reticle) is whether I would need to take a shot so fast that I don't have the few seconds to range an animal and dial or hold. That has never been my experience watching animals at long range, but I have limited experience of only a few years, plus the hours watching hunting videos, lol. I also need to positively identify an animal before I shot, and it seems like the ultrashort timeline for a quick shot makes the whole process impractical for my purposes. I suppose someone shooting pigs or other varmints would benefit from a quick system to throw lead with as great as accuracy as possible and shoot with a semi automatic.

For big game, when it comes to short shooting timelines, my buddies glassed a big deer, it went behind a tree and the glasser said shoot the buck when he comes out in the opening between the trees because it was a small window before the deer walked behind another juniper. Shooter was on the gun, dialed and ready. He saw a buck come out and killed it. The glasser then said, oops, there goes the big buck over the hill... he shot a buck, but it was a smaller one. He couldn't see anything more than antlers in his scope so he was legal, but I know guys burn buck tags on button spikes they thought were does. Target ID is such that I don't forsee the random appearance at random yards as a scenario I would face and thus need to know and practice a different system to become competent under pressure. I'd have to pass on a big game animal if it was that fast. Ambushing an animal in a narrow shooting window is different, if target ID is enough.

Here is some math to look at. Sorry, I use MOA, but I was only looking at the dangerspace and drop in inches.

The first ballistic table from JBM is for a load approximating my 7mm mag rifle. You can see if you dial for 425 yards, assuming you make a perfect shot, the bullet will stay on a 10 inch plate from 398 yards to 448 yards. As soon as you factor in 1 moa gun/shooter in the field, you decrease the danger space by a significant portion.

But, assuming a perfect shot on a 10 inch target with the scope dialed for 425 yards, you can be off by about 25 yards either way with range estimation errors. But, once you get to 550 yards, you are only in the danger space from 532 to 567 yards. That is 18 yards on the inside and 17 yards on the outside for a range estimation error. This is for a 180 vld at 3000 fps, so slower velocity cartridges suffer even worse.

Given all this math, that is why I will use the MPB zero out to 350ish and dial for everything else.

The second table I just changed danger space to 24 inches. You can see there is a dramatic difference in MPB zero and range. It is why a military context with randomly appearing hostiles in a battlefield with larger target zones and the benefits of suppressive fire, I could see some application. But, even then, instructors I have had for long range, who were deployed, use and teach what I described.

 

[hereinaz]

I didn't say it explicitly, but as I think about it, range estimation error is the limiting factor. If I learned the system and could make quick range estimation with my reticle on a well known target animal, that might be the skill that resolves range estimation errors sufficiently. He does have quick ranging features in the reticle.

I rely entirely, and some may say that is too much, on a rangefinder.

 

[Wapiti1]

I didn't say it explicitly, but as I think about it, range estimation error is the limiting factor. If I learned the system and could make quick range estimation with my reticle on a well known target animal, that might be the skill that resolves range estimation errors sufficiently. He does have quick ranging features in the reticle.

I rely entirely, and some may say that is too much, on a rangefinder.

I'd rely on the laser range finder and feel no shame. Even with a calibrated ranging feature on the reticle, or using your MIL or MOA hashes, you need a fixed size target for accurate estimation. At some distance your estimation has to be too precise for real world conditions.

An example is using a fixed 18" tall target verse a buck mule deer. Deer range in size and 18" tall targets don't.

Within something like 600 yards, errors of 25 yards can be tolerated and you'll score a hit. Beyond and the margin for error decreases rapidly. If that mule deer's chest is 20" tall instead of 18", you'll watch him walk off in the scope.

I like rangefinders.

The system, though has a lot of merit when you can estimate range as THLR stated for his example. You know the boundaries and can choose your zero. You can choose the longest as your zero, mid point, shortest or anything in between. Whatever matches easy aim points on your reticle based on your ballistics. You could then use distance references in the clearing, eyeball position relative to the boundaries, use the reticle, or range it with a laser. With practice, I think one could get pretty good with the concept. You at least have distance references to work from.

Jeremy