We have a question for the community. Hodgdon has recently published subsonic load data: https://hodgdonpowderco.com/wp-content/uploads/2023/04/subsonic-data-final-1.pdf
The list contains the following load data: .308 Win, 190 GR Hornady Sub-X, 2.69 C.O.L.: 2.690'' - 13 GR H322 Hodgdon
The bullet is 1.3'' long. Seated depth is then 0.63''. The empty case capacity is 56 GoW, the powder bulk density is 55.8 lbs/ft3.
So the fill rate (volume taken by powder in the cartridge) for this suggested load is around 33%. Only one third of the available cartridge is taken by the powder.
HOW CAN SUCH A LOAD ENSURE CONSISTENT IGNITION BY THE PRIMER? Has someone tested this load? Any feedback in general at what minimum fill rates you start to get problems /nervous?
Happy New Year!!! Not sure where we are on the Sub Sonic application scene? When working with these very low velocities always document all your variables that may change or affect the set (goal) velocity. Rifle/Barrel/Length/Twist/Grooves/Powder/Fill/No Fill/Bore Clean after each use/Reliable Powder Scale/DO NOT USE COTTON/same chronograph for each test/barrel cool/not cool/ Once you have established 'your' set of preferences you can begin. Choice of primers: AR Type Small: Rem7½, SRMag, CCIBR4, SPMag, AR Type Large: Fed215M, CCI#250, Fed210M, CCIBR-2. Use an adjustable gas block. Attached is my comprehensive list of Sub Sonic Cartridges. Enjoy. Have a Great NEW 2025.