Wildfire
Member
Still waiting.
Hey there:
Still waiting. What did they say????
Hey there:
Still waiting. What did they say????
The max load is the curve whose mean plus two standard deviations does not exceed SAAMI maximum. For those of you with a math background, you will understand the importance of "mean plus two standard deviations".
Here is the condensed version of the engineers' discussion. I would certainly like to hear from engineers or lab techs from other manufacturers to see if they follow the same procedures.
There are no lawyers involved. The lawyers only want to know if industry standards were followed during the lab tests.
There is no guarantee that following a book recipe will 100% be under max in any particular rifle.
There is no guarantee that following a book recipe will 100% be under max in any particular rifle.
For every established cartridge, the Sporting Arms and Ammunition Manufacturer's Institute (SAAMI) sets a maximum pressure. The cartridge case and the weapon itself are all capable of handling the maximum pressure without any hazard to safety, and without putting any undue wear and tear on the firearm. No factory ammunition exceeds this maximum, nor does any published handload.
Just a note for folks who are considering trying the OP's method: he's guessing at pressures, and the tools with which he is guiding his guesses are extremely variable.
How do you know that? Do you measure pressure? Do you fire enough shots and take enough measurements to be sure that an occasional round won't exceed SAAMI specs?I start well below the SAAMI specified max pressure and I stay below the SAAMI specified max pressure.
Do you know your exact chamber pressure for each experimental shot that you fire? Unless you are using a strain gauge, you do not. And if you don't know, you're guessing.How do you figure I am guessing?
Does it know the exact dimensions of your chamber and barrel? Does it know the strength of your brass and primer? And aside from your extreme faith in your guesses, the only thing brass extruding into your ejector hole is telling you is that you are substantially over SAAMI pressures. Exactly how far over is another guess.I am using a high reputable interior ballistics program which takes into consideration variables such as brass weight and case capacity, bullet, primer, powder, and cartridge OAL. I start well below the SAAMI specified max pressure and I stay below the SAAMI specified max pressure. Look at the data generated by QuickLoad and compare it to what is given to you by your typical reloading manual (Min Load and Max Load).
And nobody is forcing anyone not to do it either. We're just providing point and counterpoint for any interested readers. And there are also an awful lot of experienced shooters who have blown up rifles and injured themselves using exactly your sort of load "development". They, of course, thought they were being safe and reasonable as well.You know, some of the comments here remind me of a typical barrel breakin thread: ie. I don't believe in it and don't do it, so neither should you. Nobody is forcing ANYONE to accept this, but just be aware that there are many experience LR shooters who have been using methods such as I have described for years.
Do you know your exact chamber pressure for each experimental shot that you fire? Unless you are using a strain gauge, you do not. And if you don't know, you're guessing.
Does it know the exact dimensions of your chamber and barrel? Does it know the strength of your brass and primer?
...the only thing brass extruding into your ejector hole is telling you is that you are substantially over SAAMI pressures.
...there are also an awful lot of experienced shooters who have blown up rifles and injured themselves using exactly your sort of load "development".
I have talked many times with different folks in the ballistics bussines.
Reading brass is not a very good way of developing loads any more
Well, Don, oddly enough you are not the first pressure guesser I have ever talked with that got hot under the collar...
USSR, i agree with some of your first post, the method used to work up a load is good. But i feel data published for rifles is correct as to maximum loads using IMR Powders. The key factor in pressure difference is the make and type of bullet as i see it. I would love to see your load data. How does your load compare to published load data? What bullet,powder, calilber, primer,case, action, custom chamber or factory, barrels are you using. No wildcats please.First, I will state that this is how I approach it, and it should only be done by experienced reloaders with the knowledge and equipment to do so safely. While this has worked well for me for a number of years, I accept no responsibility or liability for your load development.
Well, there are two types of Max loads. First, there are published Max loads, which are in fact not actual Max loads and vary according to the publisher's lawyers. And then there is the actual Max load for your particular rifle. If you are not an experienced reloader, then you should stay within the publisher's Max load data. However, if you are a reloader with the knowledge and suitable equipment to determine your rifle's Max load, then here is how I approach it with a modern bolt action rifle. First, you should have a chronograph, and have an idea as to what reasonable velocity you can expect from your platform (ie. boltgun vs. autoloader, barrel length, etc.) with a particular load. Second, you should be able to look at brass and see high pressure signs. The brass is the weak link in firing ammunition in any rifle, and will show signs of stress LONG before there is any danger to the structural integrity of the rifle itself. Always start out with a load well below the published Max load. You may not always be using the same brass or primer as was used in the reloading manual, so take that into consideration as well. I like to load 3 cartridges with a particular charge weight of powder, and then load several series of 3 cartridges with a slightly heavier charge weight, varying the charge weight of each series of 3 cartridges by 0.3 grains. At the range, you will start with the lightest charge weight cartridges and run them across the chronograph. Here is where you need to have an idea as to what maximum velocity is reasonable, and what is not. In a bolt action .308 Winchester with a 26" barrel, a 175gr or 178gr bullet can usually safely attain 2750fps with a suitable powder. If you reach that velocity without pressure signs, then don't push it. Now, what are the pressure signs. The first sign of pressure (both low and high) is transfered to the primer. With low and normal pressure, there will still be some "roundness" to the edge of the primer. Once you decide to run at a slightly higher pressure (but still within the SAAMI pressure specs), you will see flattened primers. While flattened primers are generally a sign of high pressure, they do not by themselves indicate that you are anywhere near the maximum pressure specified by SAAMI. Another sign commonly associated with high pressure is cratering of the primer around the firing pin indentation, although this can also be the result of an enlarged firing pin hole in the boltface. Basically, what I am saying here is, while you should take these signs into consideration, primers can and will lie to you. So, as you continue with the next series of cartridges (assuming you have no other signs and have not met the afore mentioned predetermined optimal velocity figure), the next two signs are what bring you to your particular rifle’s Max load, and cause you to stop further load development. Oh, and make sure you have a bullet puller, because you will have no doubt loaded a series of cartridges beyond this point. What will happen next is usually you will see a shiny mark on the headstamp of the brass. What this is is the brass is beginning to flow into the extractor hole in the boltface, and it gets shaved off as you turn the bolt to extract the case. If you see this, or if the bolt becomes hard to open to extract the case, then you have reached your particular rifle’s Max load and shooting should stop and all subsequent loads should be pulled. Any subsequent reloading using the same components should have a charge weight of at least 0.5gr – 1.0gr less than the load that showed high pressure signs. Using the above method, I have been able to obtain optimal performance for LR shooting, assuming I find an accuracy node in this pressure range. YMMV.
USSR, what are your thought on measuring the web to check for high pressure?
The key factor in pressure difference is the make and type of bullet as i see it.
Sigh of high pressure or case wear? After about 3 firing was a maximun load the shiny ring appears. This is with factory rifles and FLRS standard dies. I feel its from one of 2 causes. 1.The brass has come to the end of its usefull life because of high pressure. 2. Or the FLRS dies is not adjusted correctly, the loaded round has had its shoulder pushed back to far, leaving excess head spacing. This ring does not seem to appear as fast with light loads.