Educated Reloading Newbie....with General question

Texasgrillchef said:

I guess what i am asking is, where and do the manufacturers know where to start if they are introducing a new projectile, a new caliber or even a new powder?

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I assume they start from a know point (similar bullet weight, bearing surface, case capacity, bore diameter, etc.) and use formulas that predict the internal pressures. They might even have pressure measuring equipment that provides empirical data on what’s happening inside the barrel.

Then they do what we all do, they start low, work up and observe.

There’s a member here that works for Alliant who contributes from time to time. He could provide some direct info. Without someone who’s been on the inside, we are all just guessing

The loading data for some cartridge/powder/bullet combinations haven't changed in decades. I doubt they test those, they just copy and paste the data.

I'm nether an engineer nor chemist so my thoughts are just speculation. On a brand new cartridge I think the testing/design engineers would determine how much pressure is needed or tolerated for a particular cartridge/gun. Then determine a powder by the "energy per cc" (or something similar) and the "burn speed" for peak pressure and determine a powder charge, then test on their testing equipment. Most likely, using data from a similar cartridge testing will be very useful. Like I said, just speculation...

Read up on the software called "QuickLoad". It's a mathematical modelling software that can be used to predict pressure, velocity etc based on inputs defined by the user. I imagine that the ballistic experts at each manufacturer (should they employ/contract one like Bryan Litz at Berger) will gather a bunch of information, load some ammo, measure pressure and velocity and compare to the model. If it matches the model, great! If it doesn't, the model is adjusted.

In terms of a physics/chemistry formula, there are some basic and complex formulas and equations out there. However, I'm sure you could form a general regression with multiple inputs and model against pressure or velocity to understand the interactions.

OP, I can't tell from your post if this is something you already know or don't know, but the loads that the publishers test and publish aren't tested by "checking all the indicators for overloading." They have special test fixtures/barrels that are fitted with piezo electric transducers* that directly measure the pressure, in near-real-time, during the internal ballistic process.

All the stuff about heavy bolt lift or primer flattening or ejector flow... that's for us poor slobs who don't have pressure testing equipment. Alliant and Hodgdon and Western and Vithavhouri and Sierra and Speer and Barnes and Hornady and Lyman... they aren't reliant on reading the chicken entrails by the light of the full moon. They do a test and see actual pressure curves on their computer screens. They know the peak, they know the area under the pressure curve, they know whether there were any secondary peaks.

*There's also an older method involving test fixtures with copper crushers that get compressed by the pressure, and peak pressure was calculated/extrapolated by measuring the degree of deformation. This is no longer state of the art, and there are reasons to think it could miss transient pressure spikes well above the calculated values.

Im not an engineer or ballistics expert or even a reloading expert, though I do reload. I would caution your assumption that more powder equals more bang. In general you are correct but there are certain powders you don't want to underload either (h110/ win 296). The pressure curve is also not linear, and .5 grains more may lead to a serious spike in pressure.

You should test your handloads on each gun you have in the caliber. Chambers, lands and grooves vary in dimension, certain guns like certain powders, components, and even brass. This will effect accuracy, velocity, and pressure. You can actually build loads suitable for each gun with experimentation.

In the 'old days', some of them relied on time-proven methods such as measuring case expansion, and so on.

Now it's based on science and measuring chamber pressure with industry standard equipment and conditions. Even this has evolved from the 'old' method using a copper crusher (CUP) to the 'new' method of a piezoelectric transducer (psi). You can read about it in a SAAMI manual, such as the one here for handguns: https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf

No offense meant but boy are you over thinking this! Load data is published to avoid all the math and chemistry for the most part and they test the data for safety.

Texasgrillchef said:

If i reload my own 45 acp ammo but have more then one 45 acp gun, i am assuming i should test it in all my 45 acp guns?

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Yes and no. Yes, to be sure your ammo works in all your guns. No, if like commercial ammo your ammo is produced within all SAAMI specs. If you follow the specs and your gun is correctly manufactured the ammo will fit. (especially handgun ammo)

Nature Boy said:

They might even have pressure measuring equipment that provides empirical data on what’s happening inside the barrel.

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Not might even; they do have test equipment. It used to be featured in Speer's loading book, and they out lined the process they used to develop load data.

Sometimes a feller just wants to know...

welcome to thr, texasgrillchef.

the powder combustion process is complex (chaotic) and has way too many variables to explain the whole process using the laws of physics and chemistry. instead, we use reloading manuals, based on firearm industry testing, to govern our reloading practices.

if you want to understand how the industry determines their limits, you can peruse this website: www.saami.org

luck,

murf

It's not that complicated. We can use math to predict a cartridge's performance based on powder and dimensional variables, but we can also simply load a cartridge, put it in a test rig and measure the pressure. One popular method is to use a Piezoelectric Quartz Transducer. Because we can use this on a very stout test rig in a test cell, being substantially over our goal pressure isn't as grave a concern as it would be for someone reloading at home and using a regular handgun to test. Ballisticians test loads and produce the load data we find published by bullet, powder, and reloading equipment makers. If the reloader follows that data by working up to maximum from start loads, they should become aware of any problems or unexpected variables before they get near the maximums. Once they reach maximums without any signs of being over-pressure, there is some assurance the load is safe in their gun because the gun has been proof-tested to considerably more pressure than the SAAMI or CIP maximum for the chambering. That's the margin of safety. Carelessness can still easily exceed the margin of safety.

So for example, a .357 Magnum load is tested in a test chamber and shown that it produces no more than 35,000psi peak pressure with the specific primer, case, bullet, and seating depth specifed. That load is published. A reloader can work up to that published load, checking for any signs of overpressure as a precaution against unforseen variables or mistakes. Once they reach the published load, it is most likely that load is producing no more than 35,000 psi peak pressure in their handgun which has been proof-tested to perhaps as much as 56,565 psi.

If you're loading a cartridge like .40 S&W, you can be fairly certain that a cartridge safe in one gun is likely to be safe in any gun unless it's damaged or defective. Because of that margin of safety above maximum pressure limits, you're not likely to see differences from one gun to another. If you're loading a historical cartridge like .45 Colt or .38 Special, especially ones where they were used with Black Powder, then there can be a much wider variety of guns in that chambering. Some are 140 year old antiques and others are totally modern. Rather than testing loads in all guns, be aware of those kinds of limitations and load ammo to specifications that are safe for the gun and not just that type of cartridge. The proof testing on some old guns was done a long time ago to different standards and we can't assume they meet the same standards as present-day manufactured guns.

Texasgrillchef said:

Commercial ammunition is made to work in most guns, for safety. So if i buy a box of 45 acp Winchester white box ammo. We assume it will work safely in all 45 acp
guns.

If i reload my own 45 acp ammo but have more then one 45 acp gun, i am assuming i should test it in all my 45 acp guns?

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Factory ammunition is typically sized and seated to minimum SAAMI compliant dimensional standards, as well as typically charged to produce near SAAMI compliant maximum pressure to ensure both fit and function in all firearms designed for SAAMI compliant pressure and dimensional specifications.

It’s not difficult to replicate similar minimum specification ammunition dimensions with reloaded ammunition. It’s not feasible for the typical reloader to develop and operate their own pressure testing lab, but it is feasible such the average reloader can produce ammunition of a sufficiently responsible pressure standard to operate safely within any firearm designed for SAAMI compliant ammunition.

However, as is the case when shooting factory loads, shooting these generic, minimum dimension, near-maximum power reloads may not align with accuracy in your pistols. If you want generic ammo to disperse among many of your pistols without optimizing for any of them, then you need to determine which pistol has the minimal dimensional spec, and load dimensionally for that pistol. Then you can develop a reasonably functional load for all of them, avoiding any max loading for any one of them. It’s safer to do load work up for all of them independently, then determine which has the lowest maximum tolerance.

Personally, I don’t mess with producing bulk generic ammo. If it’s just generic plinking ammo, I can buy factory ammo in bulk cheaply enough to avoid the time-sink of reloading time to produce my own. I’d rather commit that time to shooting, and when I do reload, I prefer the result to be important and specific, rather than simply generic.

entropy said:

Not might even; they do have test equipment. It used to be featured in Speer's loading book, and they out lined the process they used to develop load data.

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In fairness, not all sources of reloading data do pressure test their data. Lee is an example of a commonly recommended data source which doesn’t do any of their own pressure testing, they simply repeat data produced by others.