What topics in ballistics would you like to see explored?

[Park ranger]

Maybe what does it take to upset a bullet. Rain, a leaf, cardboard target, 1/4" tree branch. Does mass matter? Velocity? Form factor? Sg factor? ( is the 30-30 the idea brush gun?)

Wind at the muzzle or wind at the target? I never remember reading a true test of this. I was going to try it with a .22 LR and a pair of leaf blowers. Wish I had the knowledge to test the things you do Bryan!

 

[taliv]

some ideas:

effect of things like suppressors and brakes. e.g. if the use of a suppressor adds a few fps to the velocity, does it do anything else to the flight of the bullet? could things like the baffle or brake designs affect accuracy?

can we get a calculator to take into account the changes in DA on high angle long distance shots? i'm assuming none do because none of mine have a spot to enter multiple DA zones
though i suppose they might just assume DA changes proportionally to elevation in the trajectory.

would it be possible to measure interior ballistics using something like a magnet? i.e. use a magnetic bullet (like taking a steel core bullet and magnetizing it) and track its position as the firing pin hits the case, then the primer detonates, then the powder burns, etc? if possible, repeating that with various degrees of neck tension, and seating depth would be fascinating. i'm thinking something like the magnetospeed, though perhaps more sensitive and strong enough to see through the steel of the chamber wall

also is there a way to quantify the effect of mirage relative to POA really being POA? i.e. in a really strong boil, i will sometimes adjust aim slightly lower because i suspect the image i'm seeing is slightly higher than the target actually is due to the effect of mirage.

 

[taliv]

actually i'll go a step further on the magnet one and say if it is possible, building 40" long sensor that could measure the acceleration and possibly deceleration would be exceptionally interesting in determining actual optimal barrel length for a load. i've never trusted the "start with a 30inch barrel and cut off an inch at a time" tests for several reasons

and if it was detached and measured position in 3D, you could measure the harmonics as well

 

[tazzman]

Hello Bryan,

I don't know if you've ever heard of the following comments concerning the venerable .303 British: The .303, shot through the Enfields, displayed poor grouping characteristic at 100 yds, but when the shooting distance was extended to say, 500-1000yds, became much better performers. Also, by the same commenters, if rifles were zeroed at 100 yds, the groupings were substantially off to the right at those longer distances. The explanation then was given that the projectile had 'gotten to sleep'. Could that situation be explained by over-spinning the projectile, say like shooting a 52 gr. .223 in a 1-8 or 1-7.5 barrel? Or a 147 gr. 30 cal. in a 1-10 or 1-9 barrel?
I've repeatedly seen my 6mm rounds, shot at 500 yds, (r/h twist 1-10), through mirage, seem to climb to the left before impacting at the target with no apparent wind. This was done many times with 0.5 MOA results.
Does overspinning induce lateral impact changes at different distances?
Do projectiles go to sleep(stabilize)?
Your thoughts...

 

[Jet]

Bryan

Another vote here for meplate trimed/pointed. During a recent 1,000 yd match I compared my trimed/pointed 105 Hybrids vs non preped Hybrids during the sighter period. Significant difference in POI.

Also, a test on firing through turbulent air caused by shooters on bench to the left and right of test gun (believe it's called doubling). The influence, if any, of bench spacing, radial brakes, no brakes, etc. would be interesting.

Thanks for all you do.

Rich

 

[Terry]

BC on wind drift.

Is there a difference between the BC normally used, and the BC for drift?
Some claim two bullets with the same BC of different caliber and weight will fly the same, at the same velocity.

 

[Bryan Litz Ballistics]

can we get a calculator to take into account the changes in DA on high angle long distance shots? i'm assuming none do because none of mine have a spot to enter multiple DA zones
though i suppose they might just assume DA changes proportionally to elevation in the trajectory.

I can't speak for the other ballistics programs, but all the AB programs (Smartphone apps, Kestrel, PC software) does adjust DA in the trajectory model as the bullet flies up or down hill. The one exception to this is the PM Solver that comes with the book: "Applied Ballistics for Long Range Shooting". That software doesn't account for this effect but all other AB programs do.

-Bryan

 

[SHootSTraight22]

Terminal Ballistics!!!! Like the "Shooting Holes in Wounding Theory.." Just a reminder

 

[Zilla]

Also, a test on firing through turbulent air caused by shooters on bench to the left and right of test gun (believe it's called doubling). The influence, if any, of bench spacing, radial brakes, no brakes, etc. would be interesting.

Thanks for all you do.

Rich

This.

 

[Chuckhunter]

I would like to know if or what the procedure might be for adjusting your charge weight for temp and humidity changes. Is it a trial and error thing, just trying to cut down on wasting components. I have a load with a fairly wide node and shoots very well from approx. 68" right on up to 88" but on cool damp mornings, it leaves the zip code. Very curious as to how you handle that Bryan.

 

[LRCampos]

.

Hello Bryan,

I consider myself a beginer on F-Class, so may be this is a beaten point... I would like to see an analyzes on wind drift on 300, 500, 600 and 1000 yards (or meters by the way...) based on what will influence most, the wind near the muzzle, at the middle of the range or near the target?

Other stuff I would like to see is your view on ladder test, specially for initial development on an accurate load. I usually test in 5 shot groups, but shooting less through a barrel to find a good node (using the Ladder test) may be a good thing for barrel life.


You were a true gentleman with us on FCN when we were shooting right on your side for some strings, and had the patience to answer all our questions. Thank you Bryan!

Greetings from Brazil.

 

[MasonInBend]

Bryan,


What effect does gyroscopic procession have on trajectory? I have a background as a helicopter pilot, and a basic understanding of aerodynamics. I see the application of the basics of aerodynamics in many aspects of shooting, but I have yet to see where gyroscopic procession fits in. I believed it to be the same as crosswind drift or aerodynamic jump. However, gp occurs 90 degrees later in the rotation of an object, not preceding the application of the outside force. I can give a more detailed breakdown if needed.


Next question, Can we get a variable wind hold put into the ballistics calculator? Because of the WEZ tool you made, I now think of my rifle shooting in circles. My round can hit anywhere within the beam of light. The size of the beam is determined by how well I know my atmospherics and rifle, however I have yet to see a ballistics calculator give a wind hold for variable winds. I can input various set wind speeds at different distances, but I cannot enter in, "Wind 5-8mph". I would like a feature where I could enter in what the wind is gusting to, and the calculator spit out a hold where my beam would hit no matter what end of the spectrum the wind speed was at the time I pulled the trigger (based on the size of the target). For example, I know my hold is 0.5 mil for a 5mph wind and 1 mil for a 10 mph wind; so if I held 0.75 mil I would hit no matter what.

Can we get a table comparing the optimal danger spaces of various calibers? I hold the belief man came up with so many various wildcats and different calibers because he was in the search of the 'perfect' bullet. I recently compared various danger spaces of the 7mm-08 vs 6.5mm Creedmoor in hopes of narrowing down which was the truly superior caliber. I couldn't find a zero that made the 7mm-08 better. In short, I want a table that has the longest danger spaces of each caliber possible so I can compare them when shopping for a new rifle. The choices at that point are just how much recoil and the availability of brass.

In the next book can you explain with big shiny pictures for the slow thinkers out there the phenomenon known as parallax? I was very slow to pick up on how very important parallax truly is. I now resemble a boxer bobbing and weaving almost every time I go to shoot as I try to ensure that I am truly looking down the center of my scope. I'm looking for diagram showing how bad a couple degrees cant and parallax is at 100 vs 500 vs 1000.

Is it possible to create a parallax check tool or reticle? Meaning, would placing two different color dots in line with the center of the reticle help a shooter ensure he/she is always center? I.E. if I had a white dot up front and an orange dot in the rear, when I went to look down the center of my scope if I saw any orange I would know I need to re-center my eye.


I have more questions but most people find a wall of text offensive. Thank you for the time.

 

[Bryan Litz Ballistics]

Thanks for all the input guys. Much of this is being written into the long term testing plans.

Consider this thread to be ongoing; just drop in with ideas when something occurs to you.

-Bryan

 

[Canadian bushman]

How about some facts about hummer barrel & load? How do some seem to cheat the wind, not only better than others, but better than the external ballistics suggest they should? It doesn't make much sense to me, but I'm 95% sure I've seen it.

This would seem logical given all your work on the pitching and yawing of bullets in the early stages of flight.

What would differ ( @ x yds ) if the bullet launched perfectly?

 

[JarheadAZ]

I've been o/o touch recently, being on the road (estimated to be so until around Tax Day 2016).

All of my questions would relate to consistency.

Dispersion; how does it relate to parallax, and how best to optimize parallax adjustments in the most simple manner? IMHO, parallax is a far more crucial issue than most shooters accept it to be.

Barrel tuning; is it a cut and dried issue; or does it have a relationship with changes in the shooting environment? My own limited experimentation says it's never a constant; that a well resolved tuner adjustment for one day will not be well resolved on another day. I can't put a finger on the environmental conditions that influence this, and I'd like to find a way to 'cut to the chase' when readjusting. So far, I find that retuning simply adds to rounds fired and increases bore wear.

Rifling twist; as bullet length approaches excess for a given twist, accuracy improves, but only up to a point. It then appears to tip over into bullet instability. Why the improvement, and how to optimize this in the most straightforward manner?

I was initially intrigued with the claims surrounding dry bore lube, and moly in particular. But then I recalled a historical article about powder technology, and the reasoning behind the inclusion of graphite coatings for powder kernels. It seems to me that even without resorting to adding bore coatings, we have always been dealing with dry lube (graphite), that what we deal with as powder fouling is, in fact, graphite bore coating; and that including other lubes in the process only complicates the basic issue.

Might any of these questions warrant further investigation on your part?

Greg

 

[JarheadAZ]

I often see much thought and effort being expended on issues that should be (IMHO) way further down of the list of accuracy priorities. Now I can see how this could happen, being guilty often in the past of this same thing myself.

Is there, or can there be, an agreed upon list of priority subjects as they relate to accuracy; reloading issues, sighting issues, firearm tuning and maintenance issues, etc.?

Greg

 

[Bryan Litz Ballistics]

I often see much thought and effort being expended on issues that should be (IMHO) way further down of the list of accuracy priorities. Now I can see how this could happen, being guilty often in the past of this same thing myself.

Is there, or can there be, an agreed upon list of priority subjects as they relate to accuracy; reloading issues, sighting issues, firearm tuning and maintenance issues, etc.?

Greg

Greg,

This would be awesome if possible, but I don't think it's possible. Here's why.

The things that 'matter most to accuracy and precision' depend on the attributes of your rifle. Is it a light barrel hunting rifle? Long heavy barreled long range gun? Short fat BR barrel?

There's just too many things that depend on your specific system to have a universal priority list.

The work we're trying to do is aimed at finding important truths within a scoped application. For example; we know from LR competition that run-out does not have a negative effect on group sizes. BUT, I wouldn't say that's a universal fact because there may be some applications where run-out is very important. Consider that long range guns typically run long bullets with long bearing surfaces that will naturally self-align in a long throat when you chamber the round. What about something like varmint bullets in a 223? I think it's possible that the precision of a short bearing surface bullet might be much more sensitive to run-out than a longer bullet. Haven't done this particular test yet but it's on the list.

In other words, when making statements about 'what matters' and 'how much', it's very important to understand the scope of that result. I would never say that 'run-out never affects groups', based on the one test I did with 215 Hybrids in a 308 FTR rifle. I would say that: "In the testing I've done with 215's in my 308, run-out did not correlate to groups, but it might correlate for other guns/bullets".

When we design experiments for the lab, we're typically scoping wide enough to discover where things matter more and where they matter less. I think this is what makes our work valuable and special compared to all the isolated testing that individuals do on their own equipment using various methods.

So, although the list your requesting would be the holy grail, I think the best we can actually do is discover the scope of where certain truths apply.

-Bryan

 

[JarheadAZ]

Brian; thanks plenty for your insights. It correlates clearly with some things I've tried.

Of late (the past ten or so years), I've been attempting to find the absolute minimum necessary steps that ensure the basic goal of 'defeating the target'. This is an intentionally vague definition. depending on both the target and the shooter's personal goals. Precise measurements mean less here, but we all can pretty much tell the difference between a hit and a miss. Clearly this is at some odds with precision or BR style shooting, but fits better within hunting or defensive contexts.

What I have found is that even the most basic hand loading steps can achieve this goal, but only as long as close attention is paid to doing them with best consistency. I do this with essentially unmodified factory rifles, and the aim is to achieve 'better than most' success in defeating reasonable targets for the rifle type.

A simple trick I have tried is to refrain from resizing necks along their complete length, but leave the last 1/16" to 1/8". This is the portion of the neck where
donuts are likeliest to reside. It may deemphasize the impact of any such donuts, and can possibly help align the bullet and neck in the chamber better.

Another technique is to find at least two accuracy nodes and employ the lower one. This can enhance brass and bore life, and my experience suggests that no matter what node one employs, none of them can allow one to avoid learning and fully applying wind skills. If terminal performance suffers from inadequate velocity, maybe the shooting distance is too long.

Greg

 

[6BRinNZ]

Bryan - will your books cover off topics like statistical analysis when deciding on a load? It is a question that comes up fairly frequently and I'm guessing that it is a question relatively easily covered off in theory but might be hard to prove in terms of a practical outcome?

I believe that many of the arguments with load development that arise such as 100 vs 1000 load development etc come from what is important to look for and sample size to base those decisions on. It is a little akin to the arguments about what is important to measure on a bullet. Yes everything is important but what are the larger determining factors.
Is sample size a large determining factor as to the success of a load?

 

[michaelbz]

Hi, I don’t know if these issues were covered before but I think the shooting community would benefit from these topics.

Design of Experiments (DOE) and Multivariate analysis of variance (MANOVA): Most/ALL reloaders do an unnecessary full factorial experiment to determine load. Including an excel template/add in specifically for reloaders in your book would be great.

Powder sensitivity to water content: Water content in powder is dependent on both the humidity and temperature of the storage vessel. How quickly does powder water content change with a change in environment? Wood, for instance, can take months to change. If you develop your load in high temperature/high humidity, how do you account when manufacturing ammo in a lower temp/low humidity environment, and vice versa? Does the unsealed loaded round maintain the powder water content at assembly, or does the loaded round powder react almost instantaneously to temp/humidity variation? Single based extruded powder only.

Primer cup hardness, primer brisance: There is continuous debate about which is the best primer, a leading authority with money to do some decent experiments should put this argument to bed. I have seen primer cup thickness measurements on the web, but never primer cup hardness. I have seen some measurements on brisance, but never empty cases with a piezo test barrel, you might have to use a smaller piezo load cell. Multi lot testing is needed for this.

Vibrational modes and tuning: I think this topic can be greatly expanded from what is done on the Varmintal webpage. I would look at what Barnes/Arrow tech have done and build on that research. Do not focus on free vibration but rather forced dynamics on the barrel from the bullet and powder. Based off my memory, the barnes/arrow paper and the OBT method both claim the hoop/radial vibrational mode is dominant (#4 mode on the varmintal page). Are the other vibrational modes (extensional, and corkscrew/torsional twist) truly irrelevant? A set of barrel times should give us the best possible groups for a given barrel length. What is the best way to determine barrel time? Can we go further by targeting a mv for a given barrel length and powders with similar speed? How does the action change the effective barrel length from a vibration standpoint? Does primer, neck tension change barrel time?

Thanks for consideration.