Varying Load Data: Which is Reliable?

[ironsighter]

I tried to hijack another thread but realized it was out of place, so:

I'm going to be reloading for the first time and it happens to be a .243. I've chosen 85gr Sierra HPBT and IMR4320.

I've found reloading data from Sierra, IMR, Hodgson, and Lee. All of them show loads with this bullet (or same weight) and powder combination. Problem is, the data from one to the next is not consistent.

Which data should be considered the most reliable?

Also, if anyone has loaded 85 grainers in front of IMR4320 and came up with a good recipe, let me know please. Barrel is 20" @ 9.25 twist.

 

[Spawn-Inc]

It's all good data, they just used different barrels, primers, etc etc.

If there was 5 different starting loads (eg 45gr, 46gr, 48gr, 50gr) I would like start at 46 or so and work up.

 

[LUTNIT]

Factors that can have an effect on pressure of a loaded round:
-brand of case
-lot number of case
-brand of primer
-type of primer
-lot number of primer
-lot number of powder
-lot number of bullets
-chamber dimensions (these vary quite a bit)
-bore diameter
-groove diameter
-barrel length
-throat length
-throat dimensions
-ambient temperature
-ambient pressure
-humidity
-surface roughness of bore

and various other factors

These will vary between laboratories where the published loads are tested and developed. In some extreme cases the starting load in one set of data will be at the max load for another set of data; these cases are rare though.

Some people like to pick the lowest starting load, others prefer to pick the highest, others prefer to average them from multiple sources. There are some pressure signs you can look for in the cartridge cases and primers but these can vary greatly between brands and are quite unreliable. The best way to check for pressure is to use a chronograph and check the velocity of your loads and compare this to the published velocities in a book (these vary less than power weights generally).

Personally, I often find a very accurate load within the first 1/4 to 1/2 of the data and just stick with that. I don't go for maximum velocity very often so I don't usually use a chronograph for load development. Even velocity doesn't tell you exactly what your pressure is so it still isn't perfect. Some people prefer to get maximum velocity in which case you would want to check velocities and stop when you hit the max published velocity (regardless of how much powder you are using at that point); this is assuming you aren't have issues with pressure (cases sticking in the chamber, blown primers, etc.)

I have rifles that shoot low velocities at max loads because a worn barrel or loose chamber is causing the pressure to not reach published levels. I have other rifles that will have cases stick in the chamber below the max published load because they are tighter than the test actions and barrels used in the ballistic lab (or I have hotter powder, or thicker brass, or whatever).

If you want to be extra cautious, find the lowest starting load of multiple published sources and use that as your start. If you want to find the max in your rifle, you'll most likely need a chronograph.

 

[bigedp51]

ironsighter

Spawn-Inc hit the nail on the head, loading data varies because the firearm and components vary. And that is "WHY" you start low and work up your loads and also why if you change any of the reloading components you reduce the load by 10% and work up again.

Example below of case capacity between two brands of .223/5.56 cases with the exact same powder charge and 6,000 psi difference in chamber pressure.

Below is a case with 30.6 grains of H2O capacity.

And below is a case with 28.0 grains of H2O capacity.

Second example, the Quickload figures above are for the AR15 5.56 with its "longer throat. "BUT" my Savage .223 has a longer throat than either of my AR15 rifles.

Load data is never written in stone and all load data is "ball park" information.

 

[BCRider]

Like he said, different barrels used for the testing.

One factor that should be close is the peak pressure that limits the upper end of the range. You don't want to go past that. Your muzzle velocity might vary from the published data but that's OK.

If you're going to run some load testing to find which load your barrel likes be sure you make up the test batches and run them all on the same day. And hopefully that's a fairly calm and consistent day. Otherwise you're bringing in a whole new factor of wind and different days.

So your first batches should be in fairly broad steps to find a starting point. Do some loads from a starting point, a few at the lower of the maximums and two at even steps between. You're shooting the same bullets and powder so no need to shoot "foulers" between groups. Just shoot 3 to 4 of each starting from the minimum loads.

While waiting for the barrel to cool off between shots examine the primers. Flattened is OK but if the rounded corners square up you're getting close to max. If they primers form out into the chamfer of the primer pocket I'd say you're higher than you really want to be unless the primers you're using have a reputation for being a little softer.

If you start seeing this evidence of higher pressure on anything but the final near max test rounds then stop and do not shoot the next higher batch. Something is different from what it should be in this case.

One of the groups you shoot should stand out as being a little tighter. Now it's time to go back and load more of the same and in small increments for two steps out lighter and heavier. Return to another calm day and shoot those 5 batches looking for the magical combination.

I'd go with each load batch being 4 or 5 rounds worth. Any less and the results from the test shooting could be called good or bad luck.

It should not need saying but just in case.... Scope zero or hits towards the bull counts for nothing during this testing. You're only looking for group size. The groups might appear at any point on the target but that's OK.

Other's may offer pet loads. And that's fine. But due to differences found in barrel to barrel and in how you load for neck tension and such YOUR final sweet spot is likely to vary at least by a little. Even differences in volume found in different makes of brass matters when you're looking for the "sweet spot" load.

 

[ironsighter]

Excellent feedback from all of you! Thanks so much!

I am not going for max velocity. I just want a decently accurate deer load for the wife and kids to comfortably shoot. Enough velocity to maintain bullet performance out to maybe 150 yards, but nothing more is required (for now).

 

[sunray]

Usually best to use Hodgdon's data. or the powder maker's data. IMR being one of Hodgdon's. Or Lyman's. Lee does no testing themselves. They use Hodgdon's data.

 

[BCRider]

....I am not going for max velocity. I just want a decently accurate deer load for the wife and kids to comfortably shoot. Enough velocity to maintain bullet performance out to maybe 150 yards, but nothing more is required (for now).

In that case you'll find that it's easy as pie. Aim for a load that gives a good velocity that will produce a nice ethical kill while not sneaking up on the max load power. The deer will thank you by dropping right on the spot and your wife will thank you for holding it back by that last little bit so it doesn't beat up her shoulder.

I would not even worry too much about all that load testing stuff. Just start in the mid range for one test batch of 5 and another that is closer to 80% of max and let her try both. If she finds the 80% load is acceptable and it prints decently on the target call it a day. If not then let her shoot the mid range loads.

You're not looking for sub MOA for a hunting round anyway. It's nice if you get that but it's not needed and likely not achievable in any event while on a hunt. What is acceptable accuracy for hunting out to moderate distances like 200 yards? 1.5 to 2 MOA?

 

[ironsighter]

In that case you'll find that it's easy as pie. Aim for a load that gives a good velocity that will produce a nice ethical kill while not sneaking up on the max load power. The deer will thank you by dropping right on the spot and your wife will thank you for holding it back by that last little bit so it doesn't beat up her shoulder.

I would not even worry too much about all that load testing stuff. Just start in the mid range for one test batch of 5 and another that is closer to 80% of max and let her try both. If she finds the 80% load is acceptable and it prints decently on the target call it a day. If not then let her shoot the mid range loads.

You're not looking for sub MOA for a hunting round anyway. It's nice if you get that but it's not needed and likely not achievable in any event while on a hunt. What is acceptable accuracy for hunting out to moderate distances like 200 yards? 1.5 to 2 MOA?

I am considering loading some lighter "reduced recoil" loads, but several of the sources of load data warn against using less charge than the listed "starting load". Is this because it is dangerous to do so, or simply because accuracy and/or bullet performance is likely to suffer? Also, with a .243, it sort of already is "reduced recoil" so a "medium" load might be the ticket.

I would like to tune it to about 1.5 MOA. I figure that might be a bit of a challenge with the chosen rifle, but it shoots factory loads pretty well, so...

 

[BCRider]

Run a full web search on ".243 small game loads" and another for ".243 light game loads" and you'll likely find some recipes for bullet and powder options.

The light charges and typically light cast bullets or even round balls used in such loads require small charges of faster handgun powders. The trick here is the "small" in that last sentance. You're into a whole other category and using a little dusting of something like Bullseye or Titegroup handgun powder down in the bottom of all that casing volume. To someone that reloads rifle rounds it'll look totally wrong. For those that reload handgun ammo it's a fact of life. So as long as you realize that you're not going to work with almost full cases like you do with rifle powders you'll be fine.

Just be sure you learn to recognize the different powders and don't mess up between the handgun and rifle powders. We had a guy locally that was SERIOUSLY hurt when he messed up and loaded rifle cases with rifle load amounts of handgun powder. The first round sounded like the world was ending. But he chambered a second and set it off before anyone could stop him. The rifle literally blew up and the bolt came back and pretty much ruined his day along with the rest of his life. By filling the case with handgun powder he had literally created a pipe bomb with the rifle as the fragmenting casing.

Good reloading practice calls for ONE container of powder at a time on the loading bench and marking the powder in the powder dispenser with a flag of masking tape so you KNOW what you're dealing with. Don't take shortcuts and don't be tempted to work fast if working with more than one powder.

This all sounds like the end of the world. But in reality if you work with properly sharp kitchen knives and hot ranges reloading isn't any more dangerous than making dinner. It just needs the proper amount of care and consideration.

I see that Bullet Barn has .251 size 50 grain cast bullets. It's a bit of a stretch down to .243 but depending on the bore and groove diameter of your barrel this might be a nice choice for a soft hitting small game round when pushed at around 800 to 1000 fps by a light charge of handgun powder. But a web search for the ".243 small game"

 

[ironsighter]

As far as lighter .243 loads go, I didn't mean to suggest a small game load, just the "lighter end" of the normal .243 loads. I'll probably just try a few loads, starting at the minimum that I found among the various data and then fine-tune it from there until I find a sweet spot between accuracy and recoil. I doubt I will even come close to max charge.

I'm not going to let them shoot any deer farther than 100 yards, anyway.

Your warnings are not going unheeded. I only have one type of powder and I plan to load very slowly and methodically. I have no choice, really, since I will be using a Classic Lee Loader.

Thanks again for your advice.

Just to be clear; if the lowest "starting load" that I found for this bullet weight and powder combination is 35.5 grains, is there any *danger* in loading down to say 34.9 grains?

 

[LUTNIT]

In regards to reduced loads, one of the phrases thrown around a lot by everyone is SEE or Secondary Explosive Effect.

There are several theories as to how it happens and as far as I am aware only Norma has published anything about their laboratory testing on SEE's. They found it can only occur with small charges (around 30% case capacity) of slow magnum powders in a large case and it still only happens about 1/3 of the time. The result is a huge pressure spike and the rifle is usually destroyed with the shooter being injured, maimed, or killed.

One current leading theory is that the powder "flashes over" and the retarding agents magnum powders are coated with to reduce their burn rate is burned off. The powder then burns many times faster than it was designed to and the pressure increases so rapidly the bullet can't accelerate fast enough and the steel of the receiver and/or barrel fails. As far as I've read there is still not enough known about internal ballistics to verify that this is happening. Another theory that dates back over 100 years is that a shockwave is created that bounces back and forth inside the case, amplifying with each reflection, and it eventually increases enough to blow up the gun. This has been pretty thoroughly debunked though many people still reference it for some reason.

There are countless unsupported anecdotes about SEE's happening with light charges of faster powders and even pistol powders often done by highly experienced reloaders. Those cases are most likely either an obstructed bore from too little powder with the subsequent round firing into a stuck bullet, or a double or triple charge of pistol or shotgun powder which burns much faster than rifle powders. Since the evidence has literally gone up in smoke there is no way to prove it wasn't an overcharge. If you aren't using tiny charges (10-15 grains) of pistol or shotgun powders, a double charge can't happen without overflowing the case.

Some rifle powders need a minimum pressure to be reached to burn properly and if the load is too light, and the resulting pressure is too low, you can get erratic burns that sometimes work and sometimes leave intact granules of unburnt powder in your case/barrel. How much you can reduce a charge by depends on the powder, cartridge, bullet, and a lot of other factors. It is almost always safe to reduce a starting load by 10%. There are certain powders used in magnum pistol cartridge that you shouldn't but there is nothing that would be used in a .243 that would be a problem. If the published starting load is 35.5gr, there would be nothing wrong with reducing it to 34.9gr though I don't personally see a point. The difference in recoil would be undetectable. You'd be better served by using H4895 and the 60% rule for a reduced load. You can find the Hodgdon PDF that they published with the instructions but in general you take the max charge of H4895 in any cartridge, reduce it to 60% (multiply it by 0.6), and that is your new minimum charge for a reduced/youth load. Some guys say they've been using the same rule for decades with IMR4895 with great results but the document itself only mentions H4895.

 

[BCRider]

And that would be why most rifle powders have a minimum load that isn't all that far from the maximum load.

Some handgun powders share this same small allowable range. H110 is one such powder that I've used.

So yes, there's a lot of good reason to not load rifle powders to amounts lower than the starting loads. Oh sure, you can load them a FEW grains lighter. I doubt that anything nasty is going to occur if, say, 18 gns of some powder is loaded instead of the published minimum data of 20gns. But we sure don't want to take that any farther or make a habit of such a thing.

There's other powders out there that are just fine for reduced velocity and kick loads that cross over between handgun and rifle use.

To try to show this I just had a look at the .243Win load data at Hodgdon. GEEZ! THAT IS ONE FAST ROUND! For the mid weight bullets there's only a very few that dip below 3000fps!

I tried a search for the small game loads and a few turned up.

Look down a little to the loading data table https://www.kifaru.net/handload.htm

A good discussion with load recipes from another forum

http://www.go2gbo.com/forums/hand-l...-k-brass/243-low-velocity-loads-please-help!/

So at least there's some out there. I'll leave you to find the rest. I just grabbed these two off the first page of results and found them interesting to read.

 

[ironsighter]

In regards to reduced loads, one of the phrases thrown around a lot by everyone is SEE or Secondary Explosive Effect.

There are several theories as to how it happens and as far as I am aware only Norma has published anything about their laboratory testing on SEE's. They found it can only occur with small charges (around 30% case capacity) of slow magnum powders in a large case and it still only happens about 1/3 of the time. The result is a huge pressure spike and the rifle is usually destroyed with the shooter being injured, maimed, or killed.

One current leading theory is that the powder "flashes over" and the retarding agents magnum powders are coated with to reduce their burn rate is burned off. The powder then burns many times faster than it was designed to and the pressure increases so rapidly the bullet can't accelerate fast enough and the steel of the receiver and/or barrel fails. As far as I've read there is still not enough known about internal ballistics to verify that this is happening. Another theory that dates back over 100 years is that a shockwave is created that bounces back and forth inside the case, amplifying with each reflection, and it eventually increases enough to blow up the gun. This has been pretty thoroughly debunked though many people still reference it for some reason.

There are countless unsupported anecdotes about SEE's happening with light charges of faster powders and even pistol powders often done by highly experienced reloaders. Those cases are most likely either an obstructed bore from too little powder with the subsequent round firing into a stuck bullet, or a double or triple charge of pistol or shotgun powder which burns much faster than rifle powders. Since the evidence has literally gone up in smoke there is no way to prove it wasn't an overcharge. If you aren't using tiny charges (10-15 grains) of pistol or shotgun powders, a double charge can't happen without overflowing the case.

Some rifle powders need a minimum pressure to be reached to burn properly and if the load is too light, and the resulting pressure is too low, you can get erratic burns that sometimes work and sometimes leave intact granules of unburnt powder in your case/barrel. How much you can reduce a charge by depends on the powder, cartridge, bullet, and a lot of other factors. It is almost always safe to reduce a starting load by 10%. There are certain powders used in magnum pistol cartridge that you shouldn't but there is nothing that would be used in a .243 that would be a problem. If the published starting load is 35.5gr, there would be nothing wrong with reducing it to 34.9gr though I don't personally see a point. The difference in recoil would be undetectable. You'd be better served by using H4895 and the 60% rule for a reduced load. You can find the Hodgdon PDF that they published with the instructions but in general you take the max charge of H4895 in any cartridge, reduce it to 60% (multiply it by 0.6), and that is your new minimum charge for a reduced/youth load. Some guys say they've been using the same rule for decades with IMR4895 with great results but the document itself only mentions H4895.

The reason I ask specifically about 34.9 grains is because the "dipper" that comes with the .243 Lee Loader (the "2.5" dipper) holds ~34.9 grains of IMR4320. You see where I am going here? I'm trying to get away with using the included "dipper" with IMR4320 powder, instead of buying a scale. You see, when you buy a Lee Loader, you get one scoop and they tell you what powder to buy. Well, with powder availability the way it is, I bought what I could get; IMR4320.

Through this discussion, however, I have realized that in order to develop a decent load properly, I'm going to need a scale. I would have preferred not to have to spend money on a scale, but I suppose there's no way around it. I'd feel better doing it that way anyway, and eventually I will start reloading my .270 win, as well.

 

[ironsighter]

And that would be why most rifle powders have a minimum load that isn't all that far from the maximum load.

Some handgun powders share this same small allowable range. H110 is one such powder that I've used.

So yes, there's a lot of good reason to not load rifle powders to amounts lower than the starting loads. Oh sure, you can load them a FEW grains lighter. I doubt that anything nasty is going to occur if, say, 18 gns of some powder is loaded instead of the published minimum data of 20gns. But we sure don't want to take that any farther or make a habit of such a thing.

There's other powders out there that are just fine for reduced velocity and kick loads that cross over between handgun and rifle use.

To try to show this I just had a look at the .243Win load data at Hodgdon. GEEZ! THAT IS ONE FAST ROUND! For the mid weight bullets there's only a very few that dip below 3000fps!

I tried a search for the small game loads and a few turned up.

Look down a little to the loading data table https://www.kifaru.net/handload.htm

A good discussion with load recipes from another forum

http://www.go2gbo.com/forums/hand-l...-k-brass/243-low-velocity-loads-please-help!/



So at least there's some out there. I'll leave you to find the rest. I just grabbed these two off the first page of results and found them interesting to read.

Thanks for the links. I'll do some more googling.

 

[LUTNIT]

The Lee dippers have quite a bit of variability because of density variations from lot-to-lot of the same powder. The actual density of the kernels of powders can be different between lots; that's why it's best to load by weight rather than volume. The same number of molecules will weigh the same regardless of the density they're packed at. I also find the Lee dippers make for medicore at best ammo; usually 2-3" groups at 100yds with a scoped rifle. I'm not saying not to use them, that's how I got started, but be mindful with them.

Since 34.9gr is less than 3% below the starting load, if it varies by another 5% due to density, you're still good to go. I thought you wanted to reduce the load for lower velocity or recoil; I didn't realize it was because you were using dippers.
There are various tips to try to get more consistent throws using Lee dippers; there are some tutorials on YouTube. I prefer to tap the dipper until the powder settles (usually below the edge), then top it off without compressing the powder already in it, tap again until level, and then throw. Using this method I find I can get the variation from throw to throw to only a percent or two (+/- 0.5gr to 1.0gr on a 50gr charge). This is just for 50yd plinking ammo for me but when I was starting out I did use it at up to 100yds. Eventually I wanted to do better and picked up a scale and it's been expanding from there.

I still have a half dozen Lee Loader sets on my shelf. First ones I bought were .303 British and 6.5x55mm Swedish and those got quite a bit of use; several hundred rounds each. Then 7.62x54R, 44 mag, 45-70, and 30-30 but I bought a press almost immediately after buying those so I didn't use them much.

 

[ironsighter]

I thought you wanted to reduce the load for lower velocity or recoil; I didn't realize it was because you were using dippers.

Well, a bit of both, actually. I looked at the dippers chart and saw the 34.9 grains listed for the 2.5 dipper and thought "hmmm, it would be easy, cheap, and a lighter load for the girls". You're saying it is relatively safe to try it, so I will. The question is; will it shoot well? And if it doesn't, then I'll need a scale. So I sort of think I might as well buy a scale and that way I can be sure of what I am doing and try various loads. If the "dipped" load shoots well, maybe I'll use that for the most part so I don't have to weigh every single load. I dunno. (I didn't want to mention the dipper earlier because I suspected I would get berated for it).

There are various tips to try to get more consistent throws using Lee dippers; there are some tutorials on YouTube. I prefer to tap the dipper until the powder settles (usually below the edge), then top it off without compressing the powder already in it, tap again until level, and then throw. Using this method I find I can get the variation from throw to throw to only a percent or two (+/- 0.5gr to 1.0gr on a 50gr charge). This is just for 50yd plinking ammo for me but when I was starting out I did use it at up to 100yds. Eventually I wanted to do better and picked up a scale and it's been expanding from there.

Yes, I think I have seen nearly every "dipper" video on youtube. I was skeptical about them at first until I saw so many people having decent success, as long as the dipping technique was right.

I've spotted an affordable scale on Amazon with unanimously good reviews, so I might just "bite the bullet". (Sorry, I had to)

 

[jethunter]

I tried to hijack another thread but realized it was out of place, so:

I'm going to be reloading for the first time and it happens to be a .243. I've chosen 85gr Sierra HPBT and IMR4320.

I've found reloading data from Sierra, IMR, Hodgson, and Lee. All of them show loads with this bullet (or same weight) and powder combination. Problem is, the data from one to the next is not consistent.

Which data should be considered the most reliable?

Also, if anyone has loaded 85 grainers in front of IMR4320 and came up with a good recipe, let me know please. Barrel is 20" @ 9.25 twist.

ALL of that data is "reliable" for the barrel and components it was tested in. It's a good reminder of just how much variation is possible.

Different lot of powder, different brass with more or less capacity, tighter barrel and / or chamber. It all makes a difference. 10% variation is not impossible.

 

[BCRider]

....You see, when you buy a Lee Loader, you get one scoop and they tell you what powder to buy. Well, with powder availability the way it is, I bought what I could get; IMR4320.

Ah HAH! Now we see where this came from!

You caught your own mistake. Lee tells you in the Lee Loader data which powders you can use because those are the safe ones to use with that scoop. If you want to use some other powder you need to buy the set of Lee scoops and then look up or read some sort of table that comes with the set that says what weight of each powder the sizes of scoops will drop.

All in all it's easier to buy a scale....

The one I'm currently using with excellent results is this one;

http://www.ebay.com/itm/500g-x-01g-...229?pt=LH_DefaultDomain_0&hash=item51c0e79835

It has nicely lit large numbers and the zero does not drift over the short term. Worst that I've seen is I had to re-tare it to zero once over a half hour of continuous use. And that is DARN good. And best of all it remembers that I used the "grains" mode the last time and it powers up in the same mode the next time I turn it on.

And the one in the link comes with free shipping right to your door. It doesn't get any better than that as long as you're already an Ebay member. And if you're not an Ebay member I'm sure you know some that are who could order it and you just swing by and pick it up once it arrives.

 

[ironsighter]

BCRider,

Yes, I know about the dipper set. On the dipper/powder chart for IMR4320, it shows 34.9 grains for the "2.5" dipper, and shows 39.9 grains for the "2.8" dipper.

Mr. Murphy designed this, apparently, because 34.9 grains is less than the lowest "starting load" I could find, and 39.9 grain is more than the highest "max load" I could find.

So, the dippers are relatively useless with IMR4320 in .243.

If you are using that scale and it is effective, then I won't hesitate to buy it. One question, though; what are you using as a set weight to calibrate it?

I found one on Amazon for $45 (still pretty affordable, and free 2-day shipping) and it comes with a set weight and a powder tray that makes it easy to throw into the case. I'd rather spend $20 on the scale you linked to, but I'd like to know what you use as a set weight and powder tray.

Here's the one I am looking at: http://www.amazon.ca/dp/B002BDOHNA/...TF8&colid=1XHDOZEN02295&coliid=I2GHDFFJSUD6WX