AA #9 OK to underload?


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Buck13
January 17, 2013, 01:18 PM
I wanted to get #7, but LGS was out, so I bought #9. No problem for hot stuff, but my intention for my new 10 mm Witness was to start with Lite loads (power factor <180) and work up gradually. Can #9 be used slightly below starting loads (a grain or half-grain), or would it be better to go with the starting load for Unique, and have the velocity series through two powders rather than try to make the whole range with one powder?

I got Win. LP primers, if that matters...

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ATLDave
January 17, 2013, 01:53 PM
I've used AA#9 slightly below starting loads in 10mm without problem. It burns a little dirtier, but still cleaner than Unique. I took comfort from the fact that the .40 loads went WAY below the start 10mm loads, and all the 10mm start loads just looked to be max minus 10%, rather than some tested-for lower limit.

I made a few test rounds and confirmed that they worked, of course.

Buck13
January 17, 2013, 03:22 PM
What recipe did you use for .40? Accurate's website doesn't even mention #9 in .40 S&W.

Float Pilot
January 17, 2013, 03:27 PM
When I tried it in my 10mm, it worked,,, but the velocity ( pressure) variation really went nuts, thus giving me some very crappy groups.

454PB
January 17, 2013, 04:28 PM
I treat it the same as H-110/WW296. I've had bullets stuck in the barrel due to squibs with all of them.

ATLDave
January 17, 2013, 04:33 PM
What recipe did you use for .40? Accurate's website doesn't even mention #9 in .40 S&W.

I can't recall. I have a number of loading manuals, so it could be from one of a number of them. I'll check my notes when I get home and see if I can figure that out.

But I didn't use a .40 recipe, just took comfort from the fact that the high end of the .40 recipe was near what I was downloading to. Just to be clear, I wasn't going WAY light, just a bit below starting... probably one hole smaller on the Lee Auto Disk.

Obviously, I make no representations or warranties as to the wisdom or correctness or safety, etc., of any load I'm talking about. I just know I've gone a little below start loads and not had problems with function.

ATLDave
January 17, 2013, 04:35 PM
When I tried it in my 10mm, it worked,,, but the velocity ( pressure) variation really went nuts, thus giving me some very crappy groups.

Interesting. How far below were you going?

ArchAngelCD
January 17, 2013, 04:36 PM
Check the Accurate Load Data (http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf) and you will see the numbers they list are not all that different for AA#7 and AA#9 in the 10mm with the same bullets. Actually, some of the AA#9 loads generate less pressure than the AA#7 loads. I'm sure AA#9 will work just fine in the 10mm after looking at the data.

Walkalong
January 17, 2013, 05:28 PM
Under load? No, stay within the data.

Does it download pretty well, as in lower starting loads in the book, than say W296? Yes.

41 Mag
January 17, 2013, 06:32 PM
I use a LOT of #9 in my 10mm with 180gr jacketed, and to be honest the start loads aren't much to worry about if recoil is your concern.

My standard load is usually in the 13-13.5gr range depending on just who's 180gr bullet I am using. I don't recommend simply jumping right on up to the above listed amount however without working up slow. You could easily find your most accurate load somewhere before those weights.

ATLDave
January 18, 2013, 12:43 AM
OK, checked my notes and my manuals. Upon further examination, what I did was find published data in one load manual (Hornady) that went lower than other sources. Significantly lower than Speer's listing, for example. Hornady's manual is one of the few that does not appear to just base their start loads on a 10% reduction of max. So go look at a Hornady book if you want published softish data on AA#9.

Once again, no representations or warranties made, proceed at your own risk, etc.

Buck13
January 18, 2013, 02:02 AM
With the 180 gr Rainiers, the #9 starting load at 12 grains is pretty close to what I wanted. That should be fine; not sure why I was thinking otherwise this morning. With 150 JHPs, I think I'll start with 7.5 grains of Unique since I already made a dipper that should throw that consistently.

Buck13
January 18, 2013, 02:06 AM
I treat it the same as H-110/WW296. I've had bullets stuck in the barrel due to squibs with all of them.
Yikes. I'm no big fan of rapid fire, anyway, but that's a good reason to go slowly and think about each shot before taking the next!

ArchAngelCD
January 18, 2013, 02:14 AM
No reason to treat AA#9 like W296/H110, they are in no way the same. AA#9 is not hard to ignite while W296 can be especially in the colder weather. Also, Accurate does not have a standing warning not to download their #9 powder more than 3% like Hodgdon does with W296/H110.

ATLDave
January 18, 2013, 10:48 AM
With the 180 gr Rainiers, the #9 starting load at 12 grains is pretty close to what I wanted.

As suggested in my earlier post, check the Hornady manual if you want "permission" to go a little lower. Like half a grain or thereabouts.

Buck13
January 18, 2013, 01:11 PM
Made a half-box of #9 12.1 grain last night, so I'll see tomorrow how that works.

Fun fact: same dipper throws both the 7.alittle Unique and 12.1 #9 charges.

joneb
January 19, 2013, 01:07 AM
AA #9 OK to underload?
I will so no based on my experience with Accurate #9 in 357 Magnum, I have had pressure spikes with #9 using standard primers with reduced loads.
#9 works well for me in 357 mag at moderate temperatures with SPP but at colder temps it is not consistent so I am using magnum primers now.

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