Open powder: how slow it too slow?

[kneelingatlas]

We all know the formula: light bullets, slow powder, lots of gas but there has to be a point when you're just blowing unburnt powder downrange right?

I shoot 9 Major with HS6 and SP2 which seem to be the best powders for the task. I've shot 100gr bullets over 10gr of SP2 which essentially fills the case right to the brim and is crazy flat at 165PF (I know 112 is the minimum bullet weight for Major in USPSA). I've been thinking about more case capacity: 38 super, 357 SIG, .40; in theory with more case capacity you could get a bigger charge of a slower powder, but no one seems to be using slower powders, I suspect this is because any slower than say WAC, Silhouette, HS6, SP2, 3N38, etc, and you simply aren't burning the full charge of powder by the time the bullet exits a 5" barrel. Does anyone have any input on this?

I've read a little about people using N120, but nothing slower I'm aware of.

Edited January 17, 2014 by kneelingatlas

[TonyK]

Not a lot of experience but so far I just love 800X in my 45. Haven't loaded it with light bullets but I am pushing 225's at almost 900 fps and I don't notice a lot of unburnt powder on the chrono or flying back at me when the wind is wrong.

4756 will push light bullets really fast but it is filthy, one of my guns started having feed issues due to a gunked up slide after only 100 rounds through it. But it will push 185 grain plated bullets to almost 1100 fps out of my 5" 1911

Autocomp is another one that seems way down on the list and I really like what I have loaded so far.

Cant say how these might work in your 9, 38 or 40 but so far so good for me with my 45

[Justsomeguy]

In a .40 I have tried some 3N38 using 165grn bullets out of an XDm 5.25 which produced about 1182fps average for 20 shots with RMR plated HP bullets @ 1.140 OAL. This is about the slowest powder I used but the ES and SD figures were not stellar, being 78 and 17.5 respectively. I suppose it would work with lighter bullets too, but this was an SD load experiment for which it seems more than adequate, producing about 512ft/lbs. of energy and 195PF.

I have heard that Lil' Gun works well in the 38 Super and produces some fairly surprising velocities in that sized case with pretty complete burn, but I haven't tried any yet as it is hard to come by nowadays.

[cecil]

I tried 5.5gr of 7625 in my Steel Master.. but after trying Auto Comp 5.7gr its my all time favorite powder... both with 124gr jacketed bullets..

[yoshidaex]

It's a combination of things that determine what powder can be used for Open division guns.

A complete burn of powder is nice but not always possible. A slower powder will usually require more grains to reach a certain velocity in a certain caliber but you run out of space. It eventually turns into a compressed load with overly long oal's for certain calibers.

[zaphar]

I've tried using Longshot with 95gr bullets in 38 Super and it reached a point where velocity plateaued (bullet leaving the barrel before complete burn and leaving a small amount of unburnt powder behind). Switching to HS-6 allowed me to go higher with complete burn, Longshot does the same for heavier 158gr bullets.

[DRichardson]

I have played with AA#9 in my 38 super. It is pretty much like n105 in that you can't physically fit enough in the case to hurt any thing. It runs flat but is a complete pain to load and leaks from the bar on my measure. My go to is still 4756 but have been using more longshot lately.

[kneelingatlas]

I just traded for some Long shot to play around with, maybe I'll grab some more 100gr bullets for steel loads.