Why are the loads for the same bullet and powder different in different manuals? I understand barrel length is part of it but often there is a wide spread. I noticed the Hornady manual is way lower than Lee and Lyman is somewhere in between. Lee starting loads are often near max loads in Hornady. Hodgdon is usually somewhere in the middle. Sierra like Hornady is on the low end. Is it dangerous to use Lee?
Discrepancy between loading manuals
- Thread starter Old Tanker
- Start date
If a specific firearm is listed in the load data a strain gauge is glued to the barrel to measure pressure and must be calibrated with a known pressure cartridge.
In the Lyman manual they will list a universal receiver and a pressure test barrel with minimum chamber and bore dimensions. This pressure test barrel will generate the highest pressures. and their are many variations in reloading componets that change pressure. So you can see why the reloading manuals tell you to start at the suggested start load and work up.
Below with the top Lake City 5.56 case and the bottom old lot Lapua case there will be 6,000 psi difference with the same charge of 25 grains of H335. (Quickload data)
In the Lyman manual they will list a universal receiver and a pressure test barrel with minimum chamber and bore dimensions. This pressure test barrel will generate the highest pressures. and their are many variations in reloading componets that change pressure. So you can see why the reloading manuals tell you to start at the suggested start load and work up.
Below with the top Lake City 5.56 case and the bottom old lot Lapua case there will be 6,000 psi difference with the same charge of 25 grains of H335. (Quickload data)
So before using Lee, which is on the high end, I should check case brand against your chart versus the brand in the manual? I’ve been using Lyman for .223 except for Sierra 60gr TMK. Then, I checked with Sierra and went with a number in between Lyman and Sierra to start. I did pull the bullet out to 2.270 versus the 2.260 OAL. I’m shooting a Rem 700. Shot those groups with greater than MOA as compared to my favorite load of Nosler 60gr BT at .670”. My second loads with the TMK, at 2.270 OAL I went up .2 grains from Lyman start load of 24.4. I noticed that the bullet crunched the powder using anymore than 24.4 grains of Varget, so I pulled the bullet and went back to 24. Still above Sierras recommended start but below Lyman’s. I’m using Rem brass which is above the midpoint on the volume chart. Just need an experienced loader to tell me I’m safe. These are my first venture into reloading.
dcali
Bullet Maker
It’s just data. Like any scientific experiment or measurement, how you do it exactly and uncontrollable variables will change the results. It’s best not to view any one manual as *the* number. That’s why they always say “work up to a max load”.
Things off the top of my head that would make things difficult:
Barrel length
Chamber dimensions
Case dimensions (internal and external)
Primer lot variation
Powder lot variation
Ambient Temperature
Rate of test firing
Bullet lot variation
And that’s just the random stuff. There could also be systemic biases like charge weights, chronograph errors, etc. I would hope these would be small but you never know.
And finally, there is the matter that measuring pressure inside a case at 60,000 psi is simply not an easy thing to do and has its own problems to tackle, although we’ve come a long way from the old copper crushers.
In other words, reloading data is a best effort and finding the approximate max charge. I think they do a pretty good job at it, all things considered.
Any diligent shooter will gather data from multiple sources when working up a load. That might include trusted shooters, quickload, and should certainly include at least one reloading manual. It also damn well better include inspection of your brass as fired in your rifle. Velocity measurements never hurt either. In aggregate, that should point you in the direction of a safe load.
Things off the top of my head that would make things difficult:
Barrel length
Chamber dimensions
Case dimensions (internal and external)
Primer lot variation
Powder lot variation
Ambient Temperature
Rate of test firing
Bullet lot variation
And that’s just the random stuff. There could also be systemic biases like charge weights, chronograph errors, etc. I would hope these would be small but you never know.
And finally, there is the matter that measuring pressure inside a case at 60,000 psi is simply not an easy thing to do and has its own problems to tackle, although we’ve come a long way from the old copper crushers.
In other words, reloading data is a best effort and finding the approximate max charge. I think they do a pretty good job at it, all things considered.
Any diligent shooter will gather data from multiple sources when working up a load. That might include trusted shooters, quickload, and should certainly include at least one reloading manual. It also damn well better include inspection of your brass as fired in your rifle. Velocity measurements never hurt either. In aggregate, that should point you in the direction of a safe load.
JMayo
Silver $$ Contributor
Manufactured ammo is hard to pull bullets compared to handloaded ....that tells me the pressure is greater on them compared to handloads. So their data on pressure is based on ammo with a heck of a crimp or tension.
I've found I can go way past any book max before seeing pressure signs. But I don't chase crono loads, I chase poi.
I've found I can go way past any book max before seeing pressure signs. But I don't chase crono loads, I chase poi.
I suspected as much. When I went to Nosler to get load data, I chose their most accurate load for the 60gr ballistic tip. First loads I ever produced were three, 5 shot groups all under .70. Based on everyone’s feed back, I have determined that it’s a process of multiple references, making a safe interpolation then work up slowly. Thanks for the quick responses.
JSH
Gold $$ Contributor
Would that be plagiarism?
After knowing and visiting with lab guys from Hornady,Sierra and Hodgdon as mentioned it comes from the variables. Pressure guns and barrels have many variables as your rifle and mine. Lab barrels will see more use than the average guys,wear from use can slow down or speed up a load.
Load data is reference material, nothing written in stone.
Most data is soft today, not all some. Depending on what I am after and what I am working with,I will go a bit over a max load, while watching the chrono.
More times than not in the past few years you will see NO gain over most listed data when running over.
Yes.
Because some of the overloads come from Speer manuals.
My Speer Manual Number 8 from 1970 have many unsafe loads. I found this out when working up loads.
This website has also copied old 1970s data from Speer. Can be very dangerous, unless using starting loads and working up.http://stevespages.com/page8a.htm
Last edited:
Flouncer
What the heck it works for me !!
Lee has the powder publisher's warnings and disclaimers in his literature. Curiously, no bullet mfg data. ??
Just saw this - Edit: " Because some of the overloads come from Speer manuals." I have the 2nd Edition and I haven't seen any Speer or any other bullet mfg data in there.
Just saw this - Edit: " Because some of the overloads come from Speer manuals." I have the 2nd Edition and I haven't seen any Speer or any other bullet mfg data in there.
Thanks, I have yet to load anything out if the Lee manual. I like their cast, single stage press, very well made. Their .223 dies are easy to use. Crimp dies are great. Their 45-70 dies size the case too small and I had to back the die out a little. Plus the expander plug looks like it is for .45 ACP. The loading manual looks like self aggrandized marketing for Mr. Lee and sometimes, a cheap-shot at other manufacturers.
The Lee info worked well on me in the 60's , no more Lee reloading equipment, ty.
I dont know if current Lee loading data still contains the old Speer or not? Hopefully, its been edited out?
Lee owners may find this useful. http://leeprecision.net/support/index.php?/Knowledgebase/List/Index/13/product-support
wkdickinson
Gold $$ Contributor
The thing I find interesting is so many of the loads discussed on these forums are way over the maximum loads listed in reloading manuals and/or on powder manufacturer websites. For example the famous "Carolina Load" for a 6.5 Creed with 140gr is 44.3gr of 4831SC. The maximum load that Hogdon lists for that combination is 43.5gr, while Sierra list max at 45.6gr. I have personally fired the Carolina load and from looking at all of the signs for "over pressure" would consider it to be moderate (at least in my rifle).
Someone comment recently they were glad the Sierra included a particular powder in their latest manual. To which another contributor replied something to the effect "what does it matter, most people here start with loads above the max of most manuals anyway".
So frankly, I am not sure what "maximum" really means. Apparently it is entirely "gun specific".
shoot4fun
Gold $$ Contributor
None of the manuals ever contain the loads that provided the compilers maximum pressure (as per SAAMI specs). I have quizzed several and all said they only go to within 92% os so of the max derived from their test gun.
That said, however, it isn't hard to run into a pressure wall inside the parameters of those same loads. I would think all of us that have been doing this a while fit in that category. I know I certainly do.
Beside that is the fact that powder makeup changes lot to lot and many of us have seen the effects in that as well. Let's not even mention the effects of your climatic conditions versus those in a underground test lab.
In my early reloading years I stayed inside what my trusty old Speer and Lyman manuals told me. With much more experience under my belt I began to venture into "uncharted" territory. I've never blown up a gun but I have been places I knew I didn't belong. Usually (not always) when you get to the outer limit those loads are not in the best accuracy node any way.
That said, however, it isn't hard to run into a pressure wall inside the parameters of those same loads. I would think all of us that have been doing this a while fit in that category. I know I certainly do.
Beside that is the fact that powder makeup changes lot to lot and many of us have seen the effects in that as well. Let's not even mention the effects of your climatic conditions versus those in a underground test lab.
In my early reloading years I stayed inside what my trusty old Speer and Lyman manuals told me. With much more experience under my belt I began to venture into "uncharted" territory. I've never blown up a gun but I have been places I knew I didn't belong. Usually (not always) when you get to the outer limit those loads are not in the best accuracy node any way.
Published max loads do not always equal max pressure. Note that some data lists only velocity and others velocity and pressure. Those that list velocity only publish the load that fits the increment that is also below max. The methods of testing can also be different. Lyman uses universal receiver and test barrels while sierra uses actual firearms. As you noted, ultimately you may find that your rifle shows pressure before max listed loads.
Of the various variables listed that affect pressure any barrel length effect is trivial. Maximum pressure occurs around the time the bullet engages the rifling or shortly thereafter, depending on calibers and burn rates.
In reality, without pressure trace equipment we don’t know our pressure. If you see typical pressure signs, you are well over pressure and backing off half a grain will probably be overpressure as well.
Of the various variables listed that affect pressure any barrel length effect is trivial. Maximum pressure occurs around the time the bullet engages the rifling or shortly thereafter, depending on calibers and burn rates.
In reality, without pressure trace equipment we don’t know our pressure. If you see typical pressure signs, you are well over pressure and backing off half a grain will probably be overpressure as well.
I don’t think the amount of crimp makes a huge difference in how much pressure is developed. Peak pressure doesn’t occur at ignition but slightly later after the bullet has moved out of the case. Also, IIRC, the case expands to fill the chamber and the neck expands off the bullet before the bullet starts moving. So a heavily crimped case might have a little more initial pressure, it’s unlikely peak pressure would change.
Of course, I willingly defer to any professional ballistics consultants.........
Like has been mentioned, reloading manual data is just a rough guide and it’s wise to always start low and work up. I REALLY like a chronograph for load development. It gives great feedback on the very first shot. Generally, it takes a similar amount of pressure to propel a given bullet at a certain velocity in a given length barrel with a certain powder. This assumes the barrel is in decent shape.
How I use it is this way. If I want to use a 190 grain LR Accubond in a 300 RUM, and the Nosler manual shows 3150 fps with a 95 grains of H9999 as a max load; I would start with 86 grains and load 3-shot groups of 88, 90, 92, 94, 95, and 96 gains.
If I were to get to 3150 fps at 92 grains, I would stop there and pull the bullets of the higher loads. If I were to get to 96 grains and be at 3100 fps, I would load up 97 grains.
If I see ANY pressure signs at all anywhere in load development I stop. For smaller capacity cases I use smaller changes in powered charge increments.
How I use it is this way. If I want to use a 190 grain LR Accubond in a 300 RUM, and the Nosler manual shows 3150 fps with a 95 grains of H9999 as a max load; I would start with 86 grains and load 3-shot groups of 88, 90, 92, 94, 95, and 96 gains.
If I were to get to 3150 fps at 92 grains, I would stop there and pull the bullets of the higher loads. If I were to get to 96 grains and be at 3100 fps, I would load up 97 grains.
If I see ANY pressure signs at all anywhere in load development I stop. For smaller capacity cases I use smaller changes in powered charge increments.
The books are only a guide nothing more.
I have a target barrel with a load giving me what I need speed and accuracy. I setup another rifle as a spare as a just in case. The barrel came from a different manufacturer I needed 2 grains more powder to get the same velocity. Neither of these loads are on the edge.
I have a target barrel with a load giving me what I need speed and accuracy. I setup another rifle as a spare as a just in case. The barrel came from a different manufacturer I needed 2 grains more powder to get the same velocity. Neither of these loads are on the edge.
ronemus
Gold $$ Contributor
I pay attention to my chronograph, and stop when I reach the expected maximum velocity (adjusted for barrel length). If I'm at the listed max velocity, I'm somewhere close to max pressure. Once "pressure signs" appear, the load is way beyond maximum and approaching nuclear.
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