05-06-2022, 05:15 PM
AA didnt load Varget under 123gr Scenar for factory ammo, rather its one of the many powders tested when Bill A. laid down the initial baseline of published load data for 6.5 Grendel to support the cartridge.
Powders he tested with calibrated test breech under the 123gr Scenar included:
N140
N540
H4895
Varget
W748
BC-C(2)
AA2520
Factory canister powder
Not only was the pressure test breech used for developing those loads, but was maintained and constantly referenced for their ammunition manufacturing operations, to sustain a set of safe standards applied to each batch.
Weve had that data since the mid-late 2000s, and it wasnt just tested ad hoc, since hes a formally-trained ordnance engineer from the UK MoD intimately familiar with those processes.
As to simulations, I grew up in an environment where Computational Fluid Dynamics simulations were constantly being modeled, where DoD was looking for faster and faster computers to run those simulations, but still always tested that data in the real world.
Even after testing the CFD modeling iterations in extremely expensive wind tunnels, the real-world performance of several programs proved to have nasty surprises once taken to the air, including catastrophic failures and loss of life.
More often than not, the simulations were not really valid, and surprises seemed to rear their heads as a rule.
The main attraction to CFD and computer modeling is cost-savings. If we can model all the variables accurately, then it can save a lot of money in trial and error in the real world.
We might be inching closer and closer to that place in limited aerospace circles who have billions in funding, but QL is nowhere near there when it comes to internal ballistics, as proven by the 9,000-20,000psi variances we see when compared to real-world pressure test data.
The way to know what the chamber pressure actually is involves building a pressure test breech with gauges and an instrumented measuring apparatus, calibrating that test set, then taking measurements.
The published data you see from AA, Hodgdons, Lapua/Vihtavuori, Western Powders, Sierra, etc. follows SAAMI standards with test breech data, not highly-flawed simulations.
Powders he tested with calibrated test breech under the 123gr Scenar included:
N140
N540
H4895
Varget
W748
BC-C(2)
AA2520
Factory canister powder
Not only was the pressure test breech used for developing those loads, but was maintained and constantly referenced for their ammunition manufacturing operations, to sustain a set of safe standards applied to each batch.
Weve had that data since the mid-late 2000s, and it wasnt just tested ad hoc, since hes a formally-trained ordnance engineer from the UK MoD intimately familiar with those processes.
As to simulations, I grew up in an environment where Computational Fluid Dynamics simulations were constantly being modeled, where DoD was looking for faster and faster computers to run those simulations, but still always tested that data in the real world.
Even after testing the CFD modeling iterations in extremely expensive wind tunnels, the real-world performance of several programs proved to have nasty surprises once taken to the air, including catastrophic failures and loss of life.
More often than not, the simulations were not really valid, and surprises seemed to rear their heads as a rule.
The main attraction to CFD and computer modeling is cost-savings. If we can model all the variables accurately, then it can save a lot of money in trial and error in the real world.
We might be inching closer and closer to that place in limited aerospace circles who have billions in funding, but QL is nowhere near there when it comes to internal ballistics, as proven by the 9,000-20,000psi variances we see when compared to real-world pressure test data.
The way to know what the chamber pressure actually is involves building a pressure test breech with gauges and an instrumented measuring apparatus, calibrating that test set, then taking measurements.
The published data you see from AA, Hodgdons, Lapua/Vihtavuori, Western Powders, Sierra, etc. follows SAAMI standards with test breech data, not highly-flawed simulations.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
