Chronograph Challenge and chasing ES/SD

[dverna]

I got into a bit of a controversy this week.

I see a folks using chronographs and have never understood why a cast bullet shooter would need one. In fact, I cannot understand why most people would need one.

I have whittled my main rifles down to a bunch of .223/5.56's and .308's. I did some back of the envelop calculations of the difference in POI if ES is 100 fps, and could not see much difference in making hits at 300 yards with .223 or 400 yards with the .308

My assumption is that because I average about 1 MOA in the .223's and maybe a bit more in the .308's the loads I have are "good". ES doesn't matter...right?

I understand that at long ranges (over 600 yards) ES will cause greater POI changes but I do not work out there. I assume most shooters do not either. So I wonder why would anyone worry about ES for pistols loads, cast loads and jacketed hunting loads.

I have never been able to understand "ladder load development" either and that needs a chronograph. I am "old school" and use incremental load development to find a decent load then shoot a bunch of groups to confirm it was not a fluke. Once I get in the MOA area with a bolt gun I am done...good enough is good enough.

For those still with me, I have a NIB chronograph. Back when I got it, I could only shoot at public ranges and it would have been a PITA to set up. Being as l like trigger time and components were cheap, I kept muddling along with shooting groups for years.

So, here is the challenge. The chronograph (ProChrono) is "free" (you pay shipping). I will give it to the person who can best explain why someone with my needs could benefit from using one.

My needs are simple:
Varmints to 300 yards with .223's and 55 gr Hornady SP
Deer to 400 yards with a .308 using 150 gr Hornady Interlocks or 165 gr Sierra GameKings
Pistol calibers to 100 yards in carbines.

If you make a good enough case, I will pay the shipping! Knowledge is not free and none of the stuff I have read has made a compelling case so far. But I am willing to learn.

Mods, if this post is in the wrong forum please move. I put it here because the mantra is "You need a chronograph to develop loads" so it seems like a piece of reloading equipment.

[elmacgyver0]

I don't think you need one also, but they are a hoot to use if you are into air guns.

[Maven]

I don't know whether anyone "needs" a chronograph, Don unless they're doing extensive load development and testing. I have a Shooting Chrony F-1 and haven't used it for years because, as you mentioned, I value my trigger time more than monkeying with that device. (They are especially sensitive to light intensity and direction, I've found.) Having said this, I will add, the most important reason for owning and using a chronograph is for load development with unknown or military surplus propellants, e.g., IMR 5010, IMR 7383, WC 860, WC 820, etc. You can get repeatable results and low SD's IF you chronograph your loads.

[AnthonyB]

Load development with non-cannister powders is my excuse on the rare times I use the chrony.
Tony

[dverna]

I will let this run until midnight EST June 26th.

[Mal Paso]

I was able to work up a load for 350 Legend using 11FS powder and data for H110 as there is no data for 11FS and Cast.

I also saw the spread was over 100 FPS and cut that in half with Magnum Primers. I'm now 39 FPS slower than the Maximum H110 load and still 2 grains Light of the calculated load.

If you don't have pressure testing, how do you know without a speedometer?

[pergoman]

I may be the exception, but I use my chrono extensively. I am a competitive handgun shooter. I need to make certain power factors to qualify to shoot in certain divisions. I shoot ICORE and USPSA, for example. The major matches actually chrono your ammo and gun to ensure that you don't have a competitive advantage over others.

[M-Tecs]

I find the chrono invaluable for post 600-yard load development.

For the under 600-yard stuff once I find an accuracy load I record the velocity. When I switch lots of powder I vary the charge to equal the velocity of the old lot of powder. I find accuracy much more consistent compared to using the same charge weight. Even switching powder types it seems specific velocities tend to produce the peak accuracy.

I also use a chrono as a ROUGH pressure indicator. If the velocity is high or low something is amiss with the load development.

I am dealing mostly with target rifles or varmint rifles capable of sub 1/2 MOA ten shot groups.

My cowboy rifles and pistols have never been fired over a chrono and most likely never will be.

For handgun I need a chrono to ensure I make major.

On the gunsmithing side I have used a chrono to determine inconsistent firing pin strikes were cause velocity variations that created accuracy issues. One was on an RPA 2000 action that the owner had lost a washer. Couple of others had burs that created issues.

[stubshaft]

I use mine for load development and accuracy testing. I find it useful to find the velocity that a particular bullet shoots best at and be able to duplicate that velocity with another powder by shooting "ladder loads".

301496

I shoot a fair number of wildcat cartridges where there is no loading data or limited loading data. With a chronograph I can plot the velocity increase per grain of powder and determine when it runs out of juice and reaches a point of diminishing returns.

[414gates]

The chrony is a tool that is only necessary to indicate the relative safety of a load, because velocity is an indication of pressure, and excessive velocity means excessive pressure.

It's common practice to look for physical pressure signs on the brass or the primer, and not use a chrony, but I don't rely on that because in my testing I found that over pressure loads do not always show physical signs on the brass or the primer.

The chrony is very useful for precision rifle reloads. Precision being 1 MOA to 1000 yards. I want a load with a speed variation of single digits as the basis, and I need a chrony to find that.

[Wilderness]

Don -I don't need another chronograph, since I have had a perfectly good Oehler since about 1980. Today, I would feel lost without it. No doubt someone can benefit from yours however like I have benefited from mine.

Fine tuning published loads to the peculiarities of my rifles has been an ongoing use - if pressure tested data says a combination is OK for pressure at say 2800 fps, and my workup looks like going to 2900, I'll believe the chronograph and stop at 2800. I have also used my chronograph to sort out useful cast bullet loads for some (free) 3031 lookalike powder.

You mention ES and whether it matters. If a rifle is not too fussy about velocity, then maybe ES/SD does not matter as much. My Ruger 77V .308 is a case in point - a variety of bullet weights and loads will still pile up in a 100 meter group of no more than 3" or 4", and sometimes a lot better. Same bullet and same powder will likely produce 1.5" or so.

A lever action Marlin or Winchester is another matter entirely, and I would not shoot a group from either without also chronographing the shots. These lever actions are velocity sensitive, as indicated when someone shoots a group with 150 gn ammo, and then another with 170 gn - vertical POI at 50 m may differ by 4" or more. This extends also to velocity differences between different loads with the same bullet, say another grain of powder, and even the variation within a single group.

By plotting individual shots for POI and velocity I have determined to my own satisfaction that my Marlin 336A .30-30 shoots approximately 2" higher at 50 meters for every extra 100 fps velocity. This gives a very solid explanation for vertical stringing of some groups. Without the velocities we would be chasing around after bench technique, tightening screws, adjusting bedding etc, when the real fix is just to tighten up the SD - different powder, a bit more of it to get a good burn, same headstamp brass, maybe a softer primer etc.

Bottom line - having the individual velocities helps me explain why one load shows vertical stringing and another does not. Sort out the velocity variation and I sort out the groups - but that needs the chronograph.

[Land Owner]

I hunt meat and have enjoyed a lot of "trigger time" with feral hogs. I know my hunting land and the range finder distance to its landmarks from the stands.

I want to believe, within a chronograph's measurable certainty, the average velocity of my reloads through my barrels, and not the Mfg's published velocities through their "test barrels". I create an individual Drop Table for each rifle, bullet, and powder charge with which I hunt. I also know the Point-Blank Range of my equipment from shooting 25-yd., 100-yd., and 200 yd. targets.

Testing gives me great confidence in my equipment, my techniques, my components, and my capability to drop game, DRT, so I do not lose any to the thicket of the State's adjacent 'No Hunting' land.

[dverna]

A lever action Marlin or Winchester is another matter entirely, and I would not shoot a group from either without also chronographing the shots. These lever actions are velocity sensitive, as indicated when someone shoots a group with 150 gn ammo, and then another with 170 gn - vertical POI at 50 m may differ by 4" or more. This extends also to velocity differences between different loads with the same bullet, say another grain of powder, and even the variation within a single group.

By plotting individual shots for POI and velocity I have determined to my own satisfaction that my Marlin 336A .30-30 shoots approximately 2" higher at 50 meters for every extra 100 fps velocity. This gives a very solid explanation for vertical stringing of some groups. Without the velocities we would be chasing round after bench technique, tightening screws, adjusting bedding etc, when the real fix is just to tighten up the SD - different powder, a bit more of it to get a good burn, same headstamp brass, maybe a softer primer etc.

Bottom line - having the individual velocities helps me explain why one load shows vertical stringing and another does not. Sort out the velocity variation and I sort out the groups - but that needs the chronograph.

This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters. Trying to determine why this is happening is making me scratch my head. BTW, I am not doubting your information...only attempting to understand. You have done enough testing to confirm the phenomenon in this particular rifle, and this determination would not have been possible without chronograph data. BTW, this is the first time I have seen a chronograph make a significant contribution to developing a load for practical purposes.

Do you think barrel/action harmonics in a lever action (or at least your 336) have a greater effect than with other platforms? Thus a 100 fps difference has a more pronounced affect than a simple math calculation of POI change due to velocity change?

But your post is why I made the challenge here....to learn. What I read about using chronographs is always about "precision rifle shooting" at ranges most ethical hunters would pass on.

Also, I want to thank the others who are responding. Your information tends to confirm my understanding and opinions.

I should have added in the first post that I do not go "off the reservation". I use powders that are published for the caliber and bullet weight (or close to it). My goal is to find the most accurate load at close to peak performance. If max charge is 45 gr and my accurate load is at 43 gr. I stop working on the load. "Losing" 100-125 fps by being under maximum is not important to me.

[Messy bear]

Hi Don. I can’t tell you why you need one right now. Sounds like you use common components and follow manuals data. The best reason I could give you for keeping it around is if you start using surplus powders or developing your own load data. Or if you wanted to play with bullet weights that are uncommonly used in the calibers you have. For instance very light or heavy for caliber. It’s interesting to me how much just a primer change or lot number change in powder can make

[414gates]

This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters. Trying to determine why this is happening is making me scratch my head.

Lever actions are known for shallow rifling.

If that is the case here, it may lead to an explanation of why the trajectory is so finnicky.

[Cast10]

I’ve got an older Pact model and love it. Had it since the 80’s.

Everything about load development, shooting, casting, LIFE is all about CONSISTENCY.

With the assistance of a Chrony, a shot group will provide you with variables all designed to point to the most CONSISTENT group, regardless of on target grouping, as this may vary due to shooter. In the event you find several shot groups close in NUMBERS, the chrony can provide further insight by giving you standard deviation, extreme spread, shot per shot velocity, average velocity, energy, ballistics, and more. All these values provide you a scientific insight into the CONSISTENCY of the load you fired/developed. It may also indicate a load that varies in different firearms, that without a chrony, you could lose lots of ammo trying to provide inaccuracies. If you have one, use it as needed. Mine is used during load development.

BTW, I ‘m not looking for another, pass on the offer. Best of luck.

[DougGuy]

Everything about load development, shooting, casting, LIFE is all about CONSISTENCY.

With the assistance of a Chrony, a shot group will provide you with variables all designed to point to the most CONSISTENT group, regardless of on target grouping, as this may vary due to shooter. In the event you find several shot groups close in NUMBERS, the chrony can provide further insight by giving you standard deviation, extreme spread, shot per shot velocity, average velocity, energy, ballistics, and more. All these values provide you a scientific insight into the CONSISTENCY of the load you fired/developed. It may also indicate a load that varies in different firearms, that without a chrony, you could lose lots of ammo trying to provide inaccuracies. If you have one, use it as needed. Mine is used during load development.

^^^^THIS^^^^

CONSISTENCY is *THE* goal! When I worked on figuring out the mod I use for Lee's collet crimp handgun caliber dies, I found that my SD was under 20fps, which the modded crimp gave a good account of itself in this area of reloading. Ruger 7.5" SBH throats sized .4325" Lee C430-310-RF boolits .432" cast 50/50+2% over 17.0gr H2400, WLP primers (each case individually weighed and trickled). Loads run 1180-1200fps, and accuracy at tree stand distances is exceptionally good.

Many years ago before I knew diddly squat about nothing, I worked over a Ruger M77 in 308. Lapped locking lugs, pillar bedded screws, bedded the entire action with a 100rd box of 45 Colt ammo tied to the front sling swivel which gave upward pressure against the barrel when removed. Loaded only fire formed brass, bullets seated .025" from the leade ins of the rifling.

The cat's meow came with the crimp die! Weighed charges of H4895 under 180gr soft point plain base j words. When seating bullets, I culled any that seated easier at the press, same with the stiff ones, set them aside. Then I ran the good ones under the collet crimp. Rounds that had the crimp right on the case mouth were culled, ones that had more than about .030" of case mouth ahead of the crimp band were culled, so out of 100 pieces of LC brass I wound up with maybe 15-18 rounds that would go 3 into a guitar pick @ 200yds from a prone position. I shot a turkey with this rifle and load as mentioned, distance was a walked off 340yds, hit within 1/2" of POA.

dverna you may want to investigate the collet crimp if you aren't already, as it may bring your SD down noticeably, which would cut your MOA at distance IF you had chrony data to verify with.

[Larry Gibson]

dverna

"This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters."

Your argument is overly simplistic. It does not take into account several other things such as; the drop figures are of the center of the cone of fire and not taking into account linear dispersion of the group caused by the velocity variation, the variation in the location of barrel nodes is greater with large ES, the variation in angle of departure between rounds of different velocities, etc.

Variation of group size/accuracy with cartridge giving large ES can easily become apparent at 50 yards with handguns and even at 100 yards with rifles. Yes, you can have some, what appears to be, usable accuracy with some very inconsistent loads a t shorter ranges but for the best loads you'll want an ES with a proportionate SD that is conducive to best accuracy. That is not saying to chase the lowest ES or SD or combination of both to the lowest nth degree. Factually, most rifle and handgun cartridge loads that can give a consistent ES 50 fps or under with a proportionate SD for a 10 shot test are going to be good loads given quality bullets that are appropriate for the barrel twist. Chasing a lower ES or SD can be frustrating because once you get that low of ES/SD then the simple variation of test to test results can be misleading. A balance of a less than 50 fps ES/SD combination AND on target results at the longest range you will shoot is what most of us seek for consistent accuracy.

Having said that I'm not going to try to convince you to keep and use your chronograph. What you have been doing and are doing certainly fits your needs. Thus you, apparently, feel no "need" for a chronograph. However, your needs are not mine nor others. There are indeed benefits to using a chronograph. Whether one "needs" or can use those benefits is a matter of individual preferences.

[dverna]

Hi Don. I can’t tell you why you need one right now. Sounds like you use common components and follow manuals data. The best reason I could give you for keeping it around is if you start using surplus powders or developing your own load data. Or if you wanted to play with bullet weights that are uncommonly used in the calibers you have. For instance very light or heavy for caliber. It’s interesting to me how much just a primer change or lot number change in powder can make

I looked at buying surplus powders years ago, but would never trust a chronograph to tell me a load is safe. Muzzle velocity is not a measure of pressure when "going off the reservation". Even with known powders, I have seen data that shows little to no increase in MV with some powders as pressures exceed max. I suppose when you reach the point that adding more powder has little or no increase in MV it indicates the load is past max. pressure. Would that be correct? But what is the max pressure that happens at? It might depend on the type of powder, case capacity, length of barrel, other things? And say it happens at 60k psi. Well that is high for a .30/30 lever action. Just too many variables for me to juggle and have confidence in.

If someone would post how they use a chronograph to determine a safe load that would be worth examining. My way archaic. I start about 10% below max and work up to max. If I see flattened primers on the way up, I stop. I know that is "wrong" but I have not blown up a gun....yet.

It would an interesting discussion.

[Larry Gibson]

"Flattened primers are not always an indication of excessive pressure. I have actually pressure tested others loads where they though there was excessive pressure even though the load was below "max" in various cartridges. I've found excessive headspace caused by oversizing the case and/or setting the shoulder back to much is most often the cause. Even if that is not the case with many primers by the time you get really flattened primers [the primers are flattened all the way to the edge of the primer pocket with no rounding at the edge] the load is usually into proof load pressure range.

When using a chronograph if you know the burn rate of the surplus powder and compare velocities of max loads of similar burn rate powders then when the velocity of the test loads approaches those comparison velocities you know you are getting close. No, it is not for sure, but it is a lot better than depending on primers flatness, case head expansion, bolt lift/extraction or other such methods. That is based on the use of chronographs since '74 and pressure testing since '07 to test thousands of loads.

[dverna]

Good point Larry. My jacketed rifle load development is done at 100 yards. Recently, I expanded the range to 200 yards. That is the maximum range I can test at. My ranges could be too short to show much difference in ES. Or, I have been lucky and stumbled into loads that have a "good enough" ES without knowing it. I may have also "stacked the deck" by using good jacketed bullets and Varget for both the .223 and .308...a known accurate powder for those calibers.

I am tempted to set the damn thing up and check ES. But if I get an ES of 75 fps and am shooting good enough groups do I want to go down the ES/SD rabbit hole?

Here is an article I found. The data for 250 yards is interesting as I rarely shoot past that range. Both my rifle calibers are listed (.223, .308)

https://www.recoilweb.com/chasing-muzzle-velocity-standard-deviation-and-extreme-spread-for-precision-rifle-shooting-152257.html

Larry, thanks for the info on primers as well. You confirmed what I suspected. My method is "wrong", but it is all I have. I never go past max data as a result.

[Messy bear]

Per your question, Larry answered it perfectly as I see it. Hope you find that helpful

[jmorris]

It’s another tool in the box. You don’t need to eat healthy and see doctors but there is evidence that doing so can help.

I loaded for 25 years or so before I bought my first chronograph. I too worked up loads as you describe.

I suppose it was gun games and having to load my ammunition to a particular power factor was what made me buy my first chronograph. Depending on the game you are disqualified all together or scored so differently, you might as well have been disqualified. So that was a pretty big deal.

After owning one for awhile, I found them a nice easy way to quantify loads, ensure I was achieving appropriate velocity’s for certain projectiles to work, others to not have a sonic report.

Not the end all be all of reloading gear but just another tool that is as useful as the owner wants it to be.

[414gates]

If someone would post how they use a chronograph to determine a safe load that would be worth examining.

A chronograph on it's own can't tell you if a load is safe.

It can only tell you what the velocity is.

If you are using published load data, then it's easy.

Using an unknown powder ? Personally I'd use it for the pot plants.

It is possible to compare pressures of different loads, you just need to start off with virgin brass. Measure case diameter as close as possible to the extractor groove, or rim. Fire the load, and measure again. This needs a 1/10,000 micrometer.

This way, you can compare a max known published safe load to your surplus powder load, and this will tell you very precisely how the pressure compares.

[Wilderness]

This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters. Trying to determine why this is happening is making me scratch my head.

Do you think barrel/action harmonics in a lever action (or at least your 336) have a greater effect than with other platforms? Thus a 100 fps difference has a more pronounced affect than a simple math calculation of POI change due to velocity change?


Don - To be clear, my measurements concern cast bullet velocities in the range of 1800 - 2100 fps from a pre-Microgroove Marlin 336A used for LAS.

POI is obviously down to a lot more than simple velocity/trajectory. If is was just about trajectory, the differences over the whole velocity range would be in fractions of an inch at 50 or 100 meters. The actual calculation (Hornady calculator) suggests 0.3" difference per 100 fps per 50 meters for my velocity range. Other issues in POI are recoil, bullet time in the barrel, and no doubt barrel harmonics ("flip"). In the case of the .30-30 levers, I suspect that the effect of recoil across barrel time is the prime suspect.

For my Savage 99 .30-30 (used for real pigs), the effect is less pronounced, but it is still there. I have only group POI to go on for this rifle, but with 175 gn cast bullet, the difference in scope sight setting between 2200 fps and 2300 fps (LeverEvolution powder - thanks Larry) is 1.5 - 2.0 minutes. That rifle weights 9 lbs with scope and ammo, which might be a moderating factor. Incidentally, this is another plug for the chronograph - I load both 175 gn cast and Sierra 170 bullets to 2300 fps, but need 2.3 gns less powder for the cast than for the Sierras.

I am not a revolver shooter, but I keep seeing references to the effect of bullet weight on POI - heavier bullets shooting high due to extra recoil in relation to bullet time in the barrel.

Another example of the perversity of POI is the Lee Enfield rifle. With the same sight setting, Mk VI ammo (215 gn bullet at about 2000 fps) shot higher than MkVII (174 gn at 2440 fps) all the way to 900 yards. Within a string of shots with MkVII, the same velocity effect is evident. Up close, the lower velocity shots would be the high shots in the group and the higher velocity shots would be the lower ones. At the longer ranges the combined effect of short range POI difference and differing trajectory would bring the shots together into a tighter group. This was referred to in target shooting circles as "compensation", and was the main reason Commonwealth target shooters clung so long to the SMLE No4 7.62 conversions. By contrast the P14 and Martini Enfield .303 rifles exhibited "normal" behaviour - heavier or slower bullets shot lower, right from the start.

Oops - going off thread.

[Shawlerbrook]

Need is a highly variable word. I just bought one for some load development for my Marlin 250ai. I just think it’s a tool to give me a little additional information when loading for a caliber with not a lot of data in a rifle not common to the round.

[M-Tecs]

"This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters."

Barrel vibration harmonics can and does effect POI. You see it mostly in rifles that have velocity nodes that they perform the best at.

[Rickf1985]

With powders being so hard to find anymore I like to have the chrony so I can get data from different powders and see if my best accuracy from one powder to the next is all in the same velocity range. And so far that is exactly what I have found with my 03A3 and my AR15. Different powders call for different weights but what works best is the always very close to the same FPS no matter the powder charge. I note all of this in my charge sheets so the next time I don't have to set it all up again. I already know the proper load for whatever powder I have on hand.

[RKJ]

I don't need a 2nd Chronograph (heck, I don't need the one I have) but I like the fact that I can verify the velocities of my loads. I know what the books say the velocity is from their barrels but it's nice to see what I'm shooting from mine.

[Multra]

With ladder testing it's a useful tool to find the 'best'/consistent charge. You can fluke into a good 5 shot group with an inconsistent burn that you will never repeat. The chance you fluke into a good 5 shot group that also has a single digit SD that won't repeat is much lower.

It's also useful for making a drop chart/calculating velocity at X yards. Good luck doing that without a chrono.

[Larry Gibson]

An interesting observation I've made is the group distribution of shots vs the SD/ES ratio. This observation is not a 100% given but falls into the most often observed category. The more groups (10 shot) of a given load that is fired the more likely the shot dispersion I'll mention will be observed.

If we observe a group (10 shots) that has an SD/ES ratio less than 25% of the ES we most often see a small cluster of 7 to 9 shots with 1 to 3 shots "out" of that cluster.

If we observe a group with an SD/ES ratio of 25 - 35% the group, given an accurate load in an accurate rifle under the RPM threshold, we will see a nice tight group with all shots relatively close together. How close is dependent on the accuracy potential (cone of fire) of the rifle. This is the range of SD/ES ratio we should strive for.

If we observe a group with an SD/ES ration of 35 - 45% the group, given an accurate load in an accurate rifle under the RPM threshold, we will see a group that is not the best for accuracy potential (cone of fire) of the rifle such as a 2" group in a 1.25" capable rifle. However, the shots will be pretty evenly distributed about the group and while not particularly "accurate" it may still be useful. I'm coming to think some powders are more prone to this than others.

Again, this may be observed with just one group (10 shots) fired and maybe not. Fire several 10 shot groups with the same load in the same rifle and more than likely the pattern commensurate with the SD/ES ratio will become observable. Of course, the adverse effects of wind and called flyers must be taken into consideration.

In my opinion the reason for such distribution patterns is the closer the SD/ES ratio falls in the 25 - 35% range the more likely the bullet exit from the muzzle is at the same barrel node location. Of course, the heavier, stiffer barrels have less barrel "node" movement so the shot distribution may be less. The above is most noticeable in thinner sporter barrels using heavier cast bullets with faster velocities because they cause a larger barrel "node". Just my opinion on the "why" this is observable.

[dverna]

Larry, that is an interesting piece of information. A lower relative SD, may be detrimental?

If I understand correctly, a load with an ES of 50 fps and SD of 10 (20%), may not be as good as a load with the same ES but a SD of 15 (30%).

Is the trend you observed the same with jacketed bullets?

[15meter]

Best use of a chronograph was a tumble test 25+ years ago, a couple of guys were on the range with a chronograph they had borrowed from a buddy.

These guys were HARD core trap shooters. Their definition of an accurate rifle was hitting an 8" paper plate at 100 yards the week before deer season opened.

I had no idea why they wanted to fool with it other than it was one of the first compact chronographs available and they wanted to play with a new toy.

They set it up and shot a couple of deer rifles over it and were having fun. Until one guy remembered the box of Remington Accelerator ammo he had in his truck. Don't remember if it was 30-06 or 30-30.

For those unaware of Accelerator ammo, Remington used to load both 30-30 and 30-06 with .223 sub-caliber bullets in sabots. They did something silly like 4000+ in 30-06.

Well, the Accerator's got loaded into the gun and the first one was touched off.

And the chronograph did an absolutely beautiful triple somersault(backflip?) down the range when the sabot hit square in the digital display.

It would have been interesting to hear what the owner of the chronograph had to say to the rummies when they returned his chrono. He had a reputation of having a bit of a salty tongue.

I've got a chrono that was given to me by a friend, it was his dad's and he was never going to use it.

It's about time to get it out and take it to the range. Sky screens are set on ten foot center to center.

And you have to get out a paper manual and deal with base 8 numbers and conversions to get feet per second of each shot.

That'll freak out the young pups on the range.

[Kosh75287]

In rifles, I use it to determine M.V. to do drop calculations. In handgun, it's pretty much the same thing for the hunting revolvers, but to check for "Major" performance in .38 Super and .45 Auto. ES & SD both seem to make more of a diff with pistol/revolver ammo than with rifle rounds. <shrug>

[Kosh75287]

A chronograph on it's own can't tell you if a load is safe.

It can only tell you what the velocity is.

If you are using published load data, then it's easy.

Using an unknown powder ? Personally I'd use it for the pot plants.

It is possible to compare pressures of different loads, you just need to start off with virgin brass. Measure case diameter as close as possible to the extractor groove, or rim. Fire the load, and measure again. This needs a 1/10,000 micrometer.

This way, you can compare a max known published safe load to your surplus powder load, and this will tell you very precisely how the pressure compares.

When I get a certain velocity for a given charge weight then get a roughly proportional increase in velocity for an increase in powder charge, it SUGGESTS that I'm still in the "safe zone" of the work-up. If I go up on charge weight and get a very small increase, NO increase, or even a DECREASE in velocity, that suggests to me that further charge increases are likely to unsafe, and I should back off.

[M-Tecs]

I have found this to be mostly true. I also have seen the NO increase, or even a DECREASE in velocity with increased charge weights. I don't understand the why and I get a headache trying to understand that one.

https://www.shootingtimes.com/editorial/ammunition_st_safeloads_200810/100229#:~:text=As%20you%20increase%20the%20charge% 20further%2C%20both%20pressure,and%20you%20should% 20back%20off%20the%20powder%20charge.

There is a better way to work up a safe load. While most of us can't measure pressure, we can readily measure bullet velocity. The only special equipment you need--an accurate chronograph--is well within the means of most handloaders.

I first read about the velocity-to-charge (V/C) ratio several years ago in a loading manual published by the Somchem Ballistic Laboratory in South Africa. Simply stated, it's the bullet velocity divided by the propellant charge weight. The author was Johan Loubser, who is now the ballistician at Western Powder in Montana.

I met Loubser nearly 10 years ago in the Accurate Powder booth at the SHOT Show. The South African native struggled to effectively communicate with this ol' Southern boy. Eventually, he was successful in teaching me a few things about reloading. Fortunately, when Western Powder acquired Accurate a few years ago, my friend was part of the package.

Before immigrating to the U.S., Loubser was the ballistic specialist at Somchem's lab near Cape Town. The company's loading booklet included Loubser's insights on various ballistic performance parameters in addition to the usual load recipes. Promoting the quantitative premise of "if you don't measure it, you can't manage it," he offered a relatively simple method to help shooters assess handload performance.

First, assemble five rounds using the minimum powder charge suggested by your reloading manual. Next, fire them to determine the average velocity. Then calculate the handload's V/C ratio and compare it to the V/C values derived from recommended load data in your loading manual. Of course, you must compare apples to apples--same powder type, equal barrel length, same weight bullet, etc.

If the calculated V/C for your handload is higher as compared to the ratio derived from the load manual data, then your ammo/firearm system is generating higher pressures. You may hit the maximum load for your rifle before reaching the maximum charge weight indicated by the manual. Conversely, if the V/C ratio is lower, your system is operating at relatively lower pressures. In order to achieve maximum velocity, you may have to exceed the recommended maximum powder charge.

Loubser stated the average V/Cs for charge weights within the recommended start and max range should be almost constant. As you increase the charge further, both pressure and velocity change from a relatively linear to an exponential progression. He refers to this as the dynamic V/C range (see the graph on page 28). When the dynamic V/C exceeds 1.5 times the average V/C, pressures have become unstable, and you should back off the powder charge.

[William Yanda]

"I have never been able to understand "ladder load development" either and that needs a chronograph." Don Verna

I would argue your assertion. As I recall, my first exposure to "ladder load development" was an article explaining the process. The thrust of the article was that a chronograph was NOT necessary, results could be evaluated by point of impact. Small deviations in powder load, at some level, would give points of impact that were close together, indicating a charge that produced barrel harmonics favorable to accuracy.

[Land Owner]

Every shot tests the shooter. It does not matter that the reloads have been made to exacting standards, barrel harmonics are compatible, the gun is "inherently accurate", use of a sturdy rest (always - they are everywhere), measurable "statistics", such as ES (bs), are "small", etc., EXCEPT to increase shooter confidence!

Shooting is an equation in MANY variables. The LEAST consistent variable is the shooter himself. Practice, practice, practice makes perfect.

[Larry Gibson]

Larry, that is an interesting piece of information. A lower relative SD, may be detrimental?

If I understand correctly, a load with an ES of 50 fps and SD of 10 (20%), may not be as good as a load with the same ES but a SD of 15 (30%).

Is the trend you observed the same with jacketed bullets?

A lower SD is not necessarily "detrimental". A low ratio of SD to ES, as in your example (SD 10 fps to ES of 50 FP) possibly indicates something may not be consistent with that load. The SD is simply saying the velocity of 8 shots +/- fell within 10 fps of the average velocity. The remaining 2 shots+/- fell within the 50 fps ES.

First let me say that I'm referring to ratios based on 10 shot test strings. A 3 or even 5 shot chronograph test with attendant SD/ESs is essentially meaningless with regards to the actual SD/ES.

Is your example good or bad? If you have tracked the individual shots on target and the 2 shots went to group and it is an acceptable group for the rifle being tested, then the load is probably ok.
If the 2 shots were out of the group or even on the edge of the group that is indicating the load may not be the best.

However, remember what I said about "test to test variation" of the same load and not I spoke in past tense of the test data. Chronographing three consecutive 10 shot tests of the same load will, no doubt, give three different average velocities, SDs and ESs. In initial testing if we select one or more loads to possibly use then a series of three 10 shot tests with each should be used before the final selection. The load with the three closest Average, SD and ES will then be the one most consistent internal ballistic. The on target results will tell you the external ballistic consistency. More than likely the load with the best internal ballistics will also give the best external ballistic results, I.E. the best groups. That testing will then tell you, with about the highest level of certainty, what the average velocity, SD and ES (+/-) of that load will be out of your rifle.

Yes, the trend is the same for jacketed bullets.

Again, let me reiterate, this is not a "rule" or "theory" but is just an observable trend based on the observation of thousands of test groups in various rifle of different calibers using both cast and jacketed bullets. One must have the shooting ability from a solid bench with solid rests and a rifle capable of very good accuracy. For example, using a milsurp rifle with issue sights having a frosted or corroded barrel and milsurp bullets (pulldowns) would probably not be a good test to observe this trend. Neither would be using a lever action with open sights. However, the same test procedure will still give you the "best" load for either of those rifles. Whether or not you "need" to find that "best" load is simply a personal choice and is up to you.

[Larry Gibson]

"I have never been able to understand "ladder load development" either and that needs a chronograph." Don Verna

I would argue your assertion. As I recall, my first exposure to "ladder load development" was an article explaining the process. The thrust of the article was that a chronograph was NOT necessary, results could be evaluated by point of impact. Small deviations in powder load, at some level, would give points of impact that were close together, indicating a charge that produced barrel harmonics favorable to accuracy.

Yes, a chronograph is not needed when using the "ladder" test, either the Audette Ladder test or when incrementally testing (erroneously referred to as "ladder testing"). Both methods can be used by assessing the groups on target.

The Audette Ladder test is a limited specific test for a minor variation in charge weight of an already developed load at/for a specific range, usually in the area of 600 - 1000 yards. The Audette Ladder test is not intended to be used for load development. Some claim some mystical ability to "read" on target results and 50 or 100 yards using the Audette Ladder to develop loads. It has not been proven and, most often, when thoroughly tested proves to give erroneous results based on those mystical assumptions. Where it fails is it does not consider the cone of fire (group size at a given range) and random shot dispersion within that cone of fire. When testing at a known long range with an already developed accurate load using the Audette Ladder method with subtle charge weight variances different or the same point of impact can be detected. Detecting those variances is what Audette developed the method for, not for load development.

Incremental load test is what should be used to develop loads for rifles and handguns. It is the tried and true method developed well before my time. It is the method recommended in most every loading manual ["start low and work up, etc.]. Incremental load testing to develop a load was used for many, many years without the use of a chronograph. Loads were developed using "pressure signs" and groups size. With the advent of the readily usable chronograph with sky screens in the early '70s by Oehler affordable chronographs became a useful tool to further knowledge of what the load was actually doing. Through proper use of the chronograph during incremental load development the best load for a use can be much quicker with less expenditure of time and components. It also can give a much higher confidence level that the load is a good one.

[dverna]

Larry, I very much appreciate the information you have shared, the details/opinions you give....and your honesty.

I have learned more from this thread than expected. It has cause me to question my methods...methods that seemed to have worked for the 50+ years I have been putting holes in paper. I am reminded of the phrase, "You don't know what you don't know".

I have a new Howa .223 bolt gun I am loading for, and a new hunting bullet for one of the .308's I am wringing out. I have already made incremental loads for the .223 using 5 rounds per charge. Your opinion regarding at least 10 rounds to determine ES and SD makes sense. Even with my method of 5 shot groups I fire 5 groups to "prove" a load as there is too much variation to depend on one "wallet" group to tell the story.

With the requirements I have, varmints to 300 yards and deer to 400 yards, it may not matter much, but I have decided to at least try a more rigorous method as you have suggested. "Wasting" components and trigger time is never a 'waste' anyway...LOL.

I will still award the chronograph (maybe lightly used) or its equivalent value if I decide to keep it.

Again, thank you everyone for contributing.

[414gates]

When I get a certain velocity for a given charge weight then get a roughly proportional increase in velocity for an increase in powder charge, it SUGGESTS that I'm still in the "safe zone" of the work-up. If I go up on charge weight and get a very small increase, NO increase, or even a DECREASE in velocity, that suggests to me that further charge increases are likely to unsafe, and I should back off.

This is what nearly everybody says they do.

It makes no sense to me that no increase in velocity corresponds to a higher powder charge. Powder is gas. More powder more gas.

I have tried testing for that, but never been able to prove it to myself systematically and predictably.

Which is why I measure for pressure. It is never wrong.

[Squid Boy]

I have been shooting over chronographs since they became affordable. I now have four including a 35P and a LabRadar. I never develop a load by chronograph but by pressure. It's an interesting offer but I don't need any more. Best, Squid Boy

[MostlyLeverGuns]

The point of more powder and less speed is valid in some cases. I have found that as a powder charge is compressed, velocity may slow down until enough powder is added to make up for the reduced powder ignition due to powder compression. I ran into this in several rifles, .243, .308, and even the .45-70. It always occurred when a powder charge went from 98-99% case fill to moderately compressed, velocity could be regained by going to 'hotter' magnum primer OR adding yet another grain or two of powder, but there was a spot where another grain or two slowed things down, my best guess is the compression reduced ignition and or modified burn rate.

[BLAHUT]

I have used chronogaph extensively while building loads for long rainge work. 800,9000,1000,+. Every time powder lot changes, load changes, i spent over 5 years working on a 45/70 to get it to shoot the way i wanted, out to over 1000yds. Thats with soft lead, 500gr + bullet, iron sights, blackhorn powder, make my own lube, could not find any lube, that did what i wanted. Many who thought they knew, said coudn't be done. Rifle and load will hold the 10 ring at 1000yds. No problem, if i do my part. Same load work up for .308,30.06,6br,300mag,6x22-250 or any of the rest. This will work for close ranges, to help eliminate varibles. Only intresting gun out there, is a super accurate one.

[BLAHUT]

How do you measure for pressure ???

[Larry Gibson]

How do you measure for pressure ???

I use an Oehler M43 PBL and also a Pressure Trace II system.

[Larry Gibson]

How do you measure for pressure ???

I use an Oehler M43 PBL and also a Pressure Trace II system. Both require the use of a computer for the software program. I use a separate laptop for each and by affixing 2 strain gauges 180 degrees apart I can simultaneously measure the psi of a single shot with each device.

The M43 PBL also is a chronograph which includes muzzle and target screens which records screened velocity at 15' from muzzle then converts to muzzle velocity. The target screens (out t0 100 yards) measure the remaining velocity/TOF and the convert to BC for each shot.

The Pressure Trace II measures only the time pressure curve (trace) and associated data with it. A separate chronograph is required for velocity measurement.

Both require a strain gauge be affixed to the barrel of the test firearm directly over the center of the chamber. I affix the strain gauges at the SAAMI specified location for Piezo transducers. Thus, with some shorter cartridges I use a single shot (mostly a Contender) so the gauge can be affixed directly over the chamber at the specified SAAMI location for Piezo transducers.

[414gates]

The point of more powder and less speed is valid in some cases. I have found that as a powder charge is compressed, velocity may slow down until enough powder is added to make up for the reduced powder ignition due to powder compression. I ran into this in several rifles, .243, .308, and even the .45-70. It always occurred when a powder charge went from 98-99% case fill to moderately compressed, velocity could be regained by going to 'hotter' magnum primer OR adding yet another grain or two of powder, but there was a spot where another grain or two slowed things down, my best guess is the compression reduced ignition and or modified burn rate.

Good info, thank you.

I never came across this in my testing of max loads in 375 RUM, but I got around having to compress the powder by using a long powder drop.

[Wilderness]

An interesting observation I've made is the group distribution of shots vs the SD/ES ratio. This observation is not a 100% given but falls into the most often observed category. The more groups (10 shot) of a given load that is fired the more likely the shot dispersion I'll mention will be observed.

An interesting observation indeed Larry, and one begging for explanation.

I'm no statistician, though I did a unit at University and spent my career working with scientific types. That said, a real statistician will find my depth in a single sentence.

Our interest no doubt is in how well samples (groups) represent the whole population. For the most part we assume that the distribution of observations (e.g. velocities) in a population is "normal". Effectively, that means half the observations are above the mean, generally referred to as "average" (total of all observations divided by number of observations), and half below, and all of it following a bell shaped curve. If it is otherwise, then the distribution is "skewed", and may be better described by the "median" - the value that falls half way along the distribution. Examples are rainfall, and the weights of cast bullets before culling. In both examples the median tends to be less than the mean. The median downplays extreme values. In a "normal" distribution, mean and median will be the same.

My recollection of statistical basics is that we expect 95% of observations to fall within 1.96 SDs of the mean, so for mugs like me, SD of the POPULATION should be about 25% of the ES. Back at the sample level (groups), this is unlikely to be the exact case due to small sample size. Translating velocity variations to group pattern and size is another step that I'll leave alone.

When SD is not 25% of ES can we get different SDs out of a string of numbers with the same ES and mean? Answer is yes. A hollow distribution, i.e. a group of high numbers and a group of low numbers all on the edge of the ES, will produce a higher SD than another group with a bunch in the middle with just one number defining each end of the ES.

This deviation from 25% for SD/ES should become less as sample size increases but your observation Larry, that it becomes clearer as number of groups increases, suggests that aberrant SD/ES is not just a sample size thing and that it could be telling us something bigger.

The answer could be that the distribution for our load is NOT normal, and that the apparent misalignment of SD and ES are telling us something diagnostic about the distribution itself.

I'd love to see a response from a proper statistician or mathematician.

[Larry Gibson]

Wilderness

"This deviation from 25% for SD/ES should become less as sample size increases but your observation Larry, that it becomes clearer as number of groups increases, suggests that aberrant SD/ES is not just a sample size thing and that it could be telling us something bigger.

The answer could be that the distribution for our load is NOT normal, and that the apparent misalignment of SD and ES are telling us something diagnostic about the distribution itself."

Probable best summation of my observations.

[dverna]

Wilderness, plotting the data will tell us if a distribution is normal. That is shown by looking at the weight of cast bullets where there is a "hard stop" on maximum weight. (ie you cannot put 10 lbs of manure in a 5 lb bag). Cast bullets cannot weigh more than the maximum fill of a mold, but can weigh less due to a variety of factors (cadence, inclusions, melt temperature changes during casting, inconsistency of alloy during a session as ingots are added if alloy varies).

The type of distribution should be apparent with velocity data. If someone wants to send me a string of 20 or so velocity readings for the same load in the same gun fired on the same day I can plot them. What cannot be determined is if a normal distribution is what every load and gun will produce but it would be a start. It would be interesting to see the distribution with a SD/ES of 25% with one load and 15% with another, and another with 40%

I have some stuff to address today and will determine the winner of the challenge. I have learned a lot from this thread. My current "gut feel" wrt to the challenge is unchanged. For varmint loads for a .223 to 300 yards, and .308 deer loads to 400 yards, SD and ES may not matter much if the loads group well at 100 and 200 yards. But this thread has triggered some testing I want to do. That will be educational (for me), and I will share the results when I am done.

BTW, I see the value of a chronograph for other needs, and I acknowledged that in my first post. My query related to using a chronograph as a tool for developing loads for more "normal" needs.

[rockshooter]

I use a Labradar chronograph to explore powder applicability in pistol-caliber carbines. Longer barrels really do prefer slower powders for increased velocity. I would have guessed that, the chrono demonstrated it. Same in short-barreled revolvers.
Loren

[BLAHUT]

I use my chronograph now, mainly to maintain the same fps from lot to lot in SAME powder BRAND> for load consistency, carterage to carterage, With soft lead to keep load consistent and cut vertical displacement on target, ALSO ON ALL MY OTHER COMPITISION LOADS WITH JACKED BULLETS, I WEIGH EACH BULLET AND POWDER, more critical with the increase in distance. I WEIGH EVER POWER CHARGE, ELECTRONIC SCALE, EVERY BULLET IN A 50 ROUND BOX WILL WEIGH THE SAME, BEFORE LUBE, EVERY CARTERAGE IN BOX WILL WEIGH WITH IN 1 GR. OF THE NEXT, FOR THE ENTIRE BOX, SAME FOR JACKED BULLETS, ALL BULLETS ARE HEAVY FOR CALIBER, CONSISTENCE ON TARGET IS DRIVING FACTOR FOR ME. THE MORE CONSISTANCE OF MY LOADS, THE MORE FORGIVING FOR ME AND MY PERFORMANCE. I FOUND PRIMER BRANDS OTHER THAN FEDERAL AND CCI WERE ALL ABOUT SAME IN FPS WITH OUT CHANGING ANY THING ELSE IN LOAD. FEDERAL AND CCI GAVE 100 FPS INCREASE. I USE MAG L RIFLE PRIMERS IN ALL LOADS. ALL THIS OVER TIME I HAVE FOUND TO GIVE GOOD CONSISTANCY FOR WHAT I WANT, AT LONGER RANGES, MOST WILL WORK GREAT AT SHORTER RANGES, I HAVE ONE LOAD FOR MY .223 RIFLE THAT WILL PUT 49/50 IN THE SIZE OF 1" AT 205 YDS, MOVE BACK TO 200 AND I MIGHT AS WELL HAND THROW THEM AT THE TARGET, HAVEN'T FIGERED THIS ONE OUT YET>

[BLAHUT]

The larger the sample group ( shots fired ) the more or better the results, learned.

[mdi]

I got a chrony for checking consistency and checking my handloads for "velocity expansion threshold" and fun. I started trying some of the new SD JHP bullets and not wanting to get into the cost and effort of gel, I researched the needed velocities for various bullet performance and matched the velocities in my handloads. I got by quite well for over 30 years without one though...

[dverna]

...
Incremental load test is what should be used to develop loads for rifles and handguns. It is the tried and true method developed well before my time. It is the method recommended in most every loading manual ["start low and work up, etc.]. Incremental load testing to develop a load was used for many, many years without the use of a chronograph. Loads were developed using "pressure signs" and groups size. With the advent of the readily usable chronograph with sky screens in the early '70s by Oehler affordable chronographs became a useful tool to further knowledge of what the load was actually doing. Through proper use of the chronograph during incremental load development the best load for a use can be much quicker with less expenditure of time and components. It also can give a much higher confidence level that the load is a good one.

I have been through this thread a number of times and what Larry posted above is the essence of load development IMO. It is what I have done for five decades and it has worked for me.

I am not a "long range" shooter but I understand the significance of ES/SD in developing a load for that application. It is easy to work the numbers and understand the effect.

I have not seen a rationale for focusing on ES/SD for the parameters in my opening post. If a load is accurate enough at 100 yards or 200 yards, it is likely going to be good enough at 300 yards for the .223 and 400 yards for the .308.

There were two posters on the thread who made me think. One was Wilderness (who does not want the chronograph) and the other was Larry Gibson. I will reach out to them via PM as winners of the challenge.

[Taterhead]

I didn't read all the replies, but plan to when I have a few more minutes.

Here is why I find a chronograph useful

1) sanity check on velocity (and therefore relative proxy for pressure) when loading components for which load data is rare or non-existent.

2) dialing in a specific power factor for shooting games

3) finding rifle loads with lower extreme spreads

[Wilderness]

Don – thanks for the wrap.

Larry – your observations on SD and ES have prompted me to look at some of my old .30-30 cast bullet data. The variables being tested in a 4x2 design were presence or absence of a small amount of PSB filler, against small differences in bullet weight/alloy, and lubes. My conclusion was that none of it made much difference, and that I could therefore regard the whole test as a single series.

The interesting part for the present discussion is that although the groups for which I had all five velocities showed SD/ES of 35% to 48%, the same data treated as a single series of 37 shots produced an SD of 18 and ES 64, or 28% for SD/ES, which is getting closer to the expected 25%.

It would appear that these high SD/ES ratios at the 5 and 10 shot level may be quite compatible with a lower SD/ES ratio (25%) at the population level.

I was going to include the data but cannot figure out how to get a table from Word to CB post.

[Shiloh]

Back in the glory days of endless surplus and pulldown powder, they were nice. You could see big velocity differences from lot to lot.
In my experience, commercial canister powders are a lot more consistent from lot to lot.
The surplus powders that are available, no longer carry the bargain basement prices they used to.

Shiloh

[David2011]

This is most interesting as it is unexpected. Ballistically, a 100 fps variation cannot effect POI by 2" at 50 meters. Trying to determine why this is happening is making me scratch my head. BTW, I am not doubting your information...only attempting to understand. You have done enough testing to confirm the phenomenon in this particular rifle, and this determination would not have been possible without chronograph data. BTW, this is the first time I have seen a chronograph make a significant contribution to developing a load for practical purposes.

Do you think barrel/action harmonics in a lever action (or at least your 336) have a greater effect than with other platforms? Thus a 100 fps difference has a more pronounced affect than a simple math calculation of POI change due to velocity change?

But your post is why I made the challenge here....to learn. What I read about using chronographs is always about "precision rifle shooting" at ranges most ethical hunters would pass on.

Also, I want to thank the others who are responding. Your information tends to confirm my understanding and opinions.

I should have added in the first post that I do not go "off the reservation". I use powders that are published for the caliber and bullet weight (or close to it). My goal is to find the most accurate load at close to peak performance. If max charge is 45 gr and my accurate load is at 43 gr. I stop working on the load. "Losing" 100-125 fps by being under maximum is not important to me.

A little late, something to consider. The dwell time in the barrel plays a big part in POI. I found massive differences in POI between .44 Special velocities and Ruger/Contender only loads with my 14” Super .44 Contender. Granted, the difference was way more than 100 fps but I think the example is valid. Off of a bench and rest the 1600 fps loads shot more than 18” lower than the 850 fps loads at 50 yards.

I do abide by the philosophy of matching velocities with new batches of a powder.