Highest Velocity 180gr POWDER in my AR

[TonyRumore]

11.9gr N105 behind a 180gr Speer GD went 1391fps from my 6" Witness.  CCI300, RP cases, 1.260"

I only fired three shots.

1390fps
1392fps
1389fps

In the 6" 40 Super, running 15gr of N105, it will drive the 180 to 1565fps.

Do not try these loads unless you start low and work it up in your gun.

Tony

[Taterhead]

The way to get Accurate no. 9 to open up is to use new Starline cases and run them through the sizer first.  That sticky highly ductile case gives high bullet pull, and the slow burning A9 thrives on that. I'm pretty sure that's why there is such a wide range of reported velocities with A9 in the 10mm auto. Older cases with nitro fouling just don't have the same purchase on the bullet, and velocities are lower because of that. This trait is common among powders in general, but most pronounced with A9 in the 10mm case. My all time best groups abd velocity spreads are with A9 and 180/200 gr bullets.

[Pablo]

That makes some level of sense, but wet cleaning with stainless pins, detergent and citric acid then resizing the sticky Starline brass with a tight or undersize die should help. No lube!

[Taterhead]

That makes some level of sense, but wet cleaning with stainless pins, detergent and citric acid then resizing the sticky Starline brass with a tight or undersize die should help. No lube!

Yes, that does help. Remember that the neck expansion stem will open up the case neck somewhat so there is a limit to how narrow you can set the ID of the neck. Older brass becomes less ductile, so less neck tension over time.

This sounds like a really cool project.