Anyone done any work up on 357sig with 125gr HST pulls and AA9 powder? Was kinda thinking 12.5gr at 1.140 would be about right but wondered what data others may have. Thanks! Firearm is G20 with remsport conversion. I may also go with a longer OAL since there is room to do that.
I used 13.5 grains under the 115 grain 1400 fps
Appreciate the response. This bullet is significantly longer than other bullets that I have at similar 124/125gr weights. As I recall the 125gr HST is darn close to .600 in length.
AA9 has been the only powder I've used in the .357 Sig mainly because I have had a LOT of it. Recently I stumbled into a LOT of red dot and I'll be using that going forward from here, it uses a lot less powder per shot.
Anyway, so far I've loaded 115 JHP, 139 LRN and resized 158 grain .357 magnum bullets in both native .357 Sig brassand reformed .40 S&W.
In native, new brass with 115 grain Speer JHP I used 14.5 grains of AA9. This worked really well in my little P229 but showed pressure signs (slightly flattened primers) in my 6" 1911.
In reformed .40 with 139 gn LRN I used 9.7 grains which worked well (as usual smoky with wax bullet lube) in my P229, but failed to cycle my 6" longslide 1911.
The 158's are impractical for anybody to try because they need a really difficult resizing in the Star sizing machine.
Certainly AA9 is not the most economical choice. I decided to go with it because of how much it fills the case. I know many talk about setback issues associated with sizing, proper neck tension and crimp and I figured running this powder was a good safety net on any setback issues. My current process is as follows below and the completed rounds cant get set back with any amount of reasonable force. Run thru carbide Redding pass thru die with no lube, size with Lee steel die to flush with barrel hood with no lube, expand with NOE .357x.353 expander plug (basically an M die) installed in a Lee universal expander die, seat and then factory crimp with Lee dies.
If you are concerned about bullet set back, you can add some fingernail polish on the bullet as it is being seat to hold it tightly. SPEER and CCI do add a black bullet sealant to some of their bullet loadings...