03-15-2022, 04:39 AM
RJ,
another difference between bullets of the same weight that does affect loading is: bearing length, jacket thickness and jacket hardness, lead core alloy composition which affects hardness. these variables influence the engraving resistance which influences which powder burn rate and amount is required. in the extremes, for example, a highly aerodynamic 100gr boat tail varmint bullet with thin jacket with a pure Pb core, having little bearing length will engrave into the rifling with less force than say a 100gr. flat base thick jacketed softpoint with a Pb and antimony alloy core with longer bearing length. so even with the same powder type and lot number, these two 100gr. bullets will have different load data for them. So it is not to hard to understand why bullet maker A's 100gr bullet has different load data for the same canister grade powder than bullet maker B's 100 gr. has. And then there's the variation with brass lot numbers, primer lot numbers, different pressure testing setups, etc. and though the differences may be small, when you have a lot of them they can add up. And what a reload data book reflects is just how all those variables for that manufacturer lined up on that given day when they were pressure testing loads for that specific cartridge with the specific components they used and the testing setup that they had and the test methodologies that they used to generate the data that went into their reloading manual.
Get a look at as many reload manuals as you can and cross reference. The more knowledge the better.
have fun. be safe.
-tdbru
another difference between bullets of the same weight that does affect loading is: bearing length, jacket thickness and jacket hardness, lead core alloy composition which affects hardness. these variables influence the engraving resistance which influences which powder burn rate and amount is required. in the extremes, for example, a highly aerodynamic 100gr boat tail varmint bullet with thin jacket with a pure Pb core, having little bearing length will engrave into the rifling with less force than say a 100gr. flat base thick jacketed softpoint with a Pb and antimony alloy core with longer bearing length. so even with the same powder type and lot number, these two 100gr. bullets will have different load data for them. So it is not to hard to understand why bullet maker A's 100gr bullet has different load data for the same canister grade powder than bullet maker B's 100 gr. has. And then there's the variation with brass lot numbers, primer lot numbers, different pressure testing setups, etc. and though the differences may be small, when you have a lot of them they can add up. And what a reload data book reflects is just how all those variables for that manufacturer lined up on that given day when they were pressure testing loads for that specific cartridge with the specific components they used and the testing setup that they had and the test methodologies that they used to generate the data that went into their reloading manual.
Get a look at as many reload manuals as you can and cross reference. The more knowledge the better.
have fun. be safe.
-tdbru