Because this is a new ish round, there is no real load data that I’ve been able to find. So I’m researching this to be able to answer the questions, what data do I use for the A-max round.
As with any hand loading, it is YOUR responsibility to ensure your own safety as well as those around you. So use this data at your own risk.
What little bit of information I’ve been able to find, the A-max is a S&W 500 magnum case with the rim trimmed down a little bit to function in a semi-auto. Other than that, it’s the exact same case.
Because of this the same dies for sizing and loading the 500 magnum will load the 500 A-max. Even the case holder is the same. There’s a very slight difference in the play, but it’s very small. Just make sure the cases are well lubed, as you would do with any large caliber case.
The only difference in die usage will be the crimp. The 500 magnum uses a roll crimp where the 500 A-max uses a taper. Many dies allow you to adjust the crimp to use both roll or taper. So keep that in mind.
Now, powder, this I’m still looking in to. What I’ve found is the 500 A-max uses the same load data as the 500 magnum. However, with a S&W 500 magnum having perhaps a 8" barrel on the long side, with a 1:18.75 twist rate is not the same as a 500 A-max with a 18" barrel and a 1:24 twist rate. This means the powder used in a 500 magnum will burn too fast for a 18" barrel. So I’ll have to do much more research, including taking apart some factory loads to determine how much powder and what type was used.
In the picture below, the left most round is a 5.56 for reference only. Next moving right is a 500 magnum. Note the very slight roll crimp at the top of the case. Next round moving right is the 500 A-max, not there’s no roll at the end of the case. The case is simply squeezed around the bullet to hold it in place. Furthest right is a .50 Beowulf. Same case, with a different rim cut to use a smaller extractor from the AR15 platform. Again, a taper crimp because this is used in a semi-auto instead of a revolver like the 500 magnum.
If you have any questions are wish to add or correct me, please reply below. I’ll be adding to and making corrections as I begin testing out different bullet weights and powder charges. These will include chronograph results and accuracy of the bullets when fired from a bench vise.