Why are reloading manuals so conservative?

[scythefwd]

I have a manual, modern reloading rev.2, that shows pressure as well as velocities for max loads. When looking at the .300 win mag loads, many of the MAX never load above this amount loads were actually below SAAMI max pressures by almost 4k in some instances. Same with the .308 load data, most of the loads were 2-3k lower than the max SAAMI pressures. Why is that?

If the max SAAMI pressure for .308 win is 62k psi, why only give load data that goes up to 59 psi (some max loads were as low as 55k psi)? Why not give full max loads and put a waring that you might blow up a gun that isn't in top condition on them instead? You would bet that the manufacturers make their guns to handle the max pressure for the caliber, why can't I find load data that will let me do that?

 

[ljnowell]

Lawyers, courts, judges, and a screwed up tort system in this country.

 

[rondog]

Yep, the CYA effect. Don't give people information they can hurt themselves with, and sue you over.

 

[BADUNAME37]

You asked why not give a warning that someone may blow up a gun if using the maximum loads in a Reloading Manual that would have higher maximum charges.

The short answer is that most people do not read the "Caution"-"Warning" and any other such labels.

A lot of people see a MAXIMUM charge listed as that charge which they want to load - they figure the book doesn't lie, the gun is new, so it should be STRONG, and this is what some factory loads that are real "BARN-BURNERS" must use. So they go with it.

I know many people who do not "WORK-UP" a load, looking for signs of excessive pressure, i.e., flattened primers, hard extraction, flow of primer around firing pin, etc.

There are so many variables that need to be considered, including, but not limited to:

• Lots of Powder vary - probably not much, but they do vary.

• All scales are not necessarily calibrated to actual weights throughout the range of the scale. Any scale that has been calibrated at the factory may no longer be calibrated after shipment - if any parts on the scale have been changed at all, due to rough handling during shipment.

• Just the difference in brass thickness alone from new brass vs. brass that has been loaded a number of times would be considerable thus varying pressures.

• Differences in case volume between various brands of cases can result in changes of pressure.

• Certain bullets may be seated tight up against the lands, thus causing a spikes in pressures.

• Any deviation at all from the published loads could result in pressures so excessive that something in the gun has got to "give" - Possibly at the expense of a finger, hand, eyesight, etc.

Add up all the above variables, and add some that are not listed here, and consider "worst-case-scenarios" in that every variable is on the "HIGH" side of pressure and you are now working in pressure zones that could easily blow certain guns.

 

[ArchAngelCD]

Why are reloading manuals so conservative?

Short and simple, to limit liability...

 

[Remo-99]

If the max SAAMI pressure for .308 win is 62k psi, why only give load data that goes up to 59 psi (some max loads were as low as 55k psi)? Why not give full max loads and put a waring that you might blow up a gun that isn't in top condition on them instead?

Admin's will proberly ban my IP from this site, again. For saying such, but anyway.

Reloading data is mostly just a guide of what data those companies tested and considered safe in most firearms.
As they don't have control over which firearms their data is use in, for example a modern built boltaction in 308win is much stronger than say a 308win Re-chambered Lee Enfield SMLE that was designed over 100 years ago.

Going beyond max listed data is when you're on your own and have already been warned by powder/component companies against it and when you need to work up carefully and be fully aware of any signs that pressure limits have been reached, as most long time reloaders are aware of.

There's a few calibres that I load over max data on, and I wouldn't be doing that unless I had some faith in the strength of the action/rifle as a whole.
Brass life can be much shorter, as the action strength, on modern front locking boltactions, way exceeds the SAAMI standards for the cartridge.
So when reaching the limits of the brass it's well worth stopping there and reducing some.(a blown casehead can still have it's risks, even when the locking lugs are holding good and solid).

A modern front locking boltaction will fail somewhere in the vacinity of around 80,000psi to 120,000 psi(depending on make/design). The brass casing of the round will usually fail well before that.

i.e. Tight/hard extraction = case limits exceeded, swelled caseheads and primer pockets that barely hold a new primer in place = case limits exceeded, boltface imprints on the casehead = case limits exceeded,etc. It's the best indicators most reloaders have for excessive pressures as most don't have access to pressure testing devices. That's not the case with all actions where case limitions are above that safe pressure of those actions i.e. older/weaker designs/actions(rear locking bolt actions, lever actions, pump actions, etc.)

Unless your confident/well expeirenced enough to workup loads safely all I can say is stick the published maximums.

 

[Shrinkmd]

But not Hornady...

Their loads on several pistol rounds seem head and shoulders above what some other books say. Check out their 45 acp. Their recipe for 200 gr LSWC starts at 4.9 of Bullseye, and goes up to 6.3 or so. I made up a batch of 5.2, figuring this would be a medium starter round. Boom! Hotter than I was expecting. I do need to chrony that one, but compared to the 4.5 or 4.6 almost all the other manuals list, they are loading those up to 950 or so fps!

Then again, Lyman also had similar loads going up to 5.6 or 6.0. Unless there is something funny going on, I can't imagine shooting 45acp loads that hot.

But I do need the chrony to tell the tale.

 

[edSky]

maybe the books are written by people who actually do research, and define the parameters of their testing beforehand. perhaps they look at group size (something engineers like to call "repeatability"), in addition to pressure signs.

achieving maximum pressure may have it's applications. just like running a car for as long as possible at its maximum RPM. but engines are "engineered" to have an optimal performance range, and while they may spin really fast, their torque may drop off (and systems like cooling and lubrication may start to fail). it may be great for a 1/4 mile strip, but not so good for a 24 hour race.

do you want to set a record, or do you enjoy shooting? to each his own. it really depends on what you are after.

 

[Walkalong]

To help keep you from blowing your a** up. You should be thankful.

 

[ranger335v]

"...loads were actually below SAAMI max pressures by almost 4k in some instances."

Well, fact is, loading isn't all that precise. Pressure variations occur, the pressures we see in a book are AVERAGES, meaning they do have excursions somewhat higher than what is listed. The only way to actually know the pressire limits of any firearm is to move charges up slowly until it blows apart; then back off .2 grain. ?? Or use book max.

If anyone wants to go higher than some overly conservative book max there is nothing or no one to stop them but please don't test overloaded ammo on a crowded range.

 

[griz]

It's more than just liability. If you load a batch of any load the individual rounds will vary by several thousand PSI from each other. So they aren't just trying to keep the average pressure to a certain level, they are also looking at the maximum pressure possible with that combination. Some loads have higher spreads which forces more conservative loadings to keep the average acceptable.

It is true you can often exceed the max load in the book without damage, but the few times when you DO get damage make it a bad idea.

Edit: Well, that's what happens when I let work get in the way of posting, somebody just posted what I was getting ready to say.

 

[The Bushmaster]

And then there is the handgun that starts having high pressure signs even before reaching even Lyman's maximum load. Like my S&W mod 19 that starts having stuck cases (hard to extract) at just under maximum load...

I go with Walkalong on this...

 

[Deavis]

If you understand process variability then you can easily make a case for keeping the published pressure well beneath the maximum pressure. Just having the average pressure underneath the maximum pressure is NOT enough. There are so many factors here that could be pointed out that justify that decision but here are just a few.

1) The load manual has no control over lot-to-lot variation in powder characteristics
2) Test conditions dictated by the Z299 spec do NOT replicate your gun's chamber conditions at the moment of firing
3) Testing equipment is not all equal (barrel condition, crusher lot, calibration equipment, etc...) and will introduce variation into the data
4) You gun is not a test barrel (this should be very obvious)
5) small increases in powder charge can result in large changes in pressure (i.e. 3-sigma limits or maximum probably pressure predicted using statistical analysis)
6) No control whatsoever over your reloading techniques (seating depth, bullet choice, measuring methods, etc...)

I urge everyone to read the Z299 spec, it is enlightening to say the least if you've never read it. Before anyone brings up old manuals having stronger loads than today because we are all wimps, remember that measurement equipment has come a long way since Grandpa was shooting lead torpedos packed tightly with 2400.

 

[Cosmoline]

I haven't found the manuals to be excessively conservative. They *ARE* conservative but that's as it should be. Both because of the potential dangers due to load variations and because maxing out the load's potential is generally disadvantageous to accuracy. Even old Elmer Keith, who blew up a few Colts in his day, suggested backing off the published maximums to find the sweet spot load.

 

[Steve C]

I think most of you miss the point of the manuals and are assuming its Lawyers, a fear of litigation that dictate loads and that somehow maximum pressure is a holy grail that should be attained.

Manuals are not just a cook book to get a maximum pressure they are a guide to help you develop top notch accurate ammunition. If you read completely some manuals they will tell you that the maximum loads are given at a point where to increase beyond resulted in declining accuracy, erratic pressures and velocities not simply because a SAAMI maximum allowable pressure has been reached. In fact most manuals don't say anything about pressure other than their loads are below maximum pressure limits.

 

[Phone Guy]

What would be the advantage of loading to the maximum pressure anyway? If there was a load that was well within the pressure limits of whatever load you were shooting why go beyond that? I am just curious maybe someone could educate me?

 

[ants]

We have covered this subject two or three times in the last few years. It's probably hard to select the right search phrase, but you should be able to find those old threads with a little extra effort.

A lot of what we think is 'conservatism' is actually the engineering lab methodology for testing loads and assigning Maximum to the highest load. It's a matter of applying math to the data, and has nothing to do with lawyers and liability.

And a lot of what we think is 'conservatism' is exactly what Walkalong said.




That's why I'm very wary of buying used guns from you guys who think the warnings don't apply to you.

 

[nulfisin]

Because they want to keep you alive and not maimed. Seriously, they have an incentive to be as accurate as possible, without possibly knowing exactly what components and gun you are using. The more accurate they are, within the realms of safety, the more books they sell. What am I missing?

 

[kelbro]

Just read some of the posts here (and other loading forums) and you should understand.

Seems there is always a contingent that wants to push the envelope.

 

[Noveldoc]

Maximum pressure is way over rated. Especially if you are going for accuracy.

Tom

 

[rfwobbly]

And a lot of what we think is 'conservatism' is exactly what Walkalong said.

...and you know how dangerous those gun-slinging, Bible-totin', Republican-votin', conservative Alabamans are.

 

[Walkalong]

Yup.......

 

[freakshow10mm]

Or they use the industry standard of maximum charge plus two SDs that is still under SAAMI MAP to get their max charge.

 

[jfh]

"...IIt's a matter of applying math to the data, and has nothing to do with lawyers and liability."​

I absolutely agree, ants, as I do with freakshow10mm's comment in the post right above this one.

However, I'll bet it isn't the engineer that is making the final decision about what gets published. That decision, by some sort of upper-level manager (who may or may not be an engineer), is based on any number of considerations--the "facts" of engineering data, the legal advice about liability from the corporate lawyers, and yes, the sales department's advice about what is popular right now for marketing.

Jim H.

 

[scythefwd]

Guys, thanks for the answers. It is basically what I thought, but I still don't like it.
I don't intend to push the max limits, but I had to wonder why the hottest loads in my manual for the .300 win mag still fell under the "acceptable" pressures for the .308. I just didn't get the point of the larger case and pressure limit if you weren't actually going to use it.
Working up a load for accuracy is fine, but working up a load for certain characteristics like minimal arc, max retained energy at a x distance, while maintaining hunting accuracy could be reasons to push the limits of max pressures.