Just my perspective on a starting point.
I ordered an Accuracy International AXSR in 300 Norma Magnum and 5 boxes of Berger 230 grain Hybrid OTM Tactical cartridges for the Lapua Brass and later load development. I like Vihtavuori N500 series powders for the 300 Norma Magnum.
Using the Vihtavuori load calculator, it suggested N560, N565 and N570 powders. However, running Quickload my first assessment suggested N568 was the ideal powder based on a case capacity fill of 98% at 63,412 p.s.i. (near max), and a burn rate of 100% out of a 27 inch barrel at 2,981 f.p.s. While reviewing the “Table of powders and Cartridge Data” showing comparable powders, many powders have a 100% burnt propellant factor. However, looking at another table ”Estimates of the progress of combustion” we can see when the propellant achieves 100% as it travels down the barrel.
Powders reaching 100% early suggest a powder burn rate that is too fast, powders never reaching 100% suggest a powder burn rate to slow.
Safe reloading practices dictate a charge starting point well below max utilizing what is commonly known as a “ladder” or “Satterlee ladder test.” There are several variations of this but you’re looking for that range of charges that produce the least variance in velocity known as a “node.” There may be several nodes too. This first ladder test can have some wide increments, say .3 grains or whatever you wish. More on this later.
In searching for favorable “nodes” your bullet seating depth is not critical at this point, so start at .0003 off the lands and shoot your groups to find a node or nodes. Now the range of seating depth will depend on several factors, what is your chamber dimensions (SAAMI or custom), single or magazine feed will determine your possible range of COAL.
Once you determined your seating depth, it’s likely different from your initial starting point and therefore your case capacity is slightly different, and you should redo the “ladder test” again in smaller increments +- .5 grains on either side of your new starting charge weight in .1 grain increments to fine tune your adjusted charge weight.
When seating bullets within the range in your “node”, start at the longest length within your node range since barrel erosion only goes one way.
While I have not evaluated this, Erik Cortina says much of the bullet seating testing can be replaced with a tuner. I’m not sure, just passing along what I understood him to say.
DO NOT RELY ON ANY INFORMATION IN MY POST, CHECK EVERYTHING INDEPENDENTLY.
I ordered an Accuracy International AXSR in 300 Norma Magnum and 5 boxes of Berger 230 grain Hybrid OTM Tactical cartridges for the Lapua Brass and later load development. I like Vihtavuori N500 series powders for the 300 Norma Magnum.
Using the Vihtavuori load calculator, it suggested N560, N565 and N570 powders. However, running Quickload my first assessment suggested N568 was the ideal powder based on a case capacity fill of 98% at 63,412 p.s.i. (near max), and a burn rate of 100% out of a 27 inch barrel at 2,981 f.p.s. While reviewing the “Table of powders and Cartridge Data” showing comparable powders, many powders have a 100% burnt propellant factor. However, looking at another table ”Estimates of the progress of combustion” we can see when the propellant achieves 100% as it travels down the barrel.
Powders reaching 100% early suggest a powder burn rate that is too fast, powders never reaching 100% suggest a powder burn rate to slow.
Safe reloading practices dictate a charge starting point well below max utilizing what is commonly known as a “ladder” or “Satterlee ladder test.” There are several variations of this but you’re looking for that range of charges that produce the least variance in velocity known as a “node.” There may be several nodes too. This first ladder test can have some wide increments, say .3 grains or whatever you wish. More on this later.
In searching for favorable “nodes” your bullet seating depth is not critical at this point, so start at .0003 off the lands and shoot your groups to find a node or nodes. Now the range of seating depth will depend on several factors, what is your chamber dimensions (SAAMI or custom), single or magazine feed will determine your possible range of COAL.
Once you determined your seating depth, it’s likely different from your initial starting point and therefore your case capacity is slightly different, and you should redo the “ladder test” again in smaller increments +- .5 grains on either side of your new starting charge weight in .1 grain increments to fine tune your adjusted charge weight.
When seating bullets within the range in your “node”, start at the longest length within your node range since barrel erosion only goes one way.
While I have not evaluated this, Erik Cortina says much of the bullet seating testing can be replaced with a tuner. I’m not sure, just passing along what I understood him to say.
DO NOT RELY ON ANY INFORMATION IN MY POST, CHECK EVERYTHING INDEPENDENTLY.
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