.357 Magnum Sierra 125 gr bullet and AA#9

H

Homebrewer

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First post! Be gentle! :D

I can't seem to get a satisfactory answer to my question from multiple sources.

Here's my dilemma:

I'm using a new combination of powder and bullets for my .357 Magnum. I want some load recommendations for the combination of Sierra 125 gr JSP and Accurate Arms #9 powder. My Sierra manual shows a range of 15.5 gr to 17.9 gr for AA#9 and their 125 gr bullets. However, when I look at the Western Powder website, I see a range of 14.1 gr to 15.6 gr for a Nosler 125 gr JHP bullet and AA#9.

I am using the Sierra 125 gr bullets, but I've never seen such a discrepancy before. I've been reloading for years, but the maximum powder charge of one manual is the minimum in another. ARGH! I'm not looking for a super hot load, just a safe, mid-range load for target shooting.

Thanks.
 
Welcome to TFL Homebrewer.

but the maximum powder charge of one manual is the minimum in another.
Click to expand...

It's actually not all that uncommon. It happens. And it can drive you nuts if you think about it too much. I learned years ago not to get too wrapped around the axle over it. I pick one, discard the other, and go.

If I have a bullet where I have their manual - such as Sierra - then I would use their data and ignore the other. I would start low and work my way up as needed for my application. If I don't have the manual for the bullet, then I will tend to use the more conservative charge weight data.

Which leads to a couple questions: 1) What is your application? 2) What gun will be firing these? More specifically, the barrel length?

A bit about your bullet/powder combination . . .

You have a rather light bullet with a rather slow powder. The combination leans toward the awkward. The powder, being so slow, won't run clean efficient and consistent with that lighter bullet until you get to the top end of the load scale. And even at that point, it won't lend itself to a shorter barreled gun, as there will be a lot of muzzle flash and recoil.

AA#9 works in 357 Magnum IF the bullet is heavy (think 158) and the barrel long (at least 6"). With lighter bullets and shorter barrels, AA#9 will get really flashy, noisy, and with tons of thrust recoil - all for very little velocity gain in that condition.

With my 357's (3" & 4" bbls), and with 125 grain bullets, I consider AA#7 to be the slowest propellant I would use. And usually it's something even a little faster like Unique or Power Pistol - if that gives some perspective. I do have an 8-3/8" bbl 357; and I might consider AA#9/125gn for it. But, since it's a safe queen, I wouldn't bother making such a specialized round.
 
but the maximum powder charge of one manual is the minimum in another.
Click to expand...

Different bullets, different test guns, different cases & primers, possibly even different lot#s of powder, and different people deciding where to start, and reading when to quit.


I have run AA#9 in .44 Magnum loads for the Desert Eagle, never bothered with it in .357 Mag, where I am firmly wedded to 2400 for heavier loads.

With my .357s (6", 6.5", 10" & 18") I can use slower powders effectively. Win 296/H110, 2400 etc., AA#9 is actually on the faster end of what I use in .357 Magnum. I do have one 4 inch .357, a S&W Model 66, which I inherited, and I might consider a faster powder for it, but since its a safe queen, I wouldn't bother making such a specialized round. ;)
 
I have a S&W 686 with 6" barrel.

I just did a large batch of .357 Mag with 158 gr bullets and was looking for something different. Unfortunately, AA#9 is my only pistol powder at the moment and I have about 500 of the 125 gr bullets.

So, I think I'll play it safe and use 15.0 gr of AA#9 to start and see how it goes.
 
In my experience, AA#9 when pushed close to max charge performs very well. I don't use it in 357, so my results may be different. When using it in 10mm, with 180 gold dots and the max charge 14.9gr, I get great velocity and very very low extreme spread in my 6" kkm precision barrel.

Chronograph from 10' glock 20 kkm precision
180gr speer gold dot
Starline brass
Winchester large pistol primers
1.260" oal

Hi 1388
Low 1380

Es 8fps

10 shot string

I'd say work up to sierra's max and check for pressure and accuracy. I was pleasantly surprised with my results and this has become my favorite load for whitetails here in central Ohio.

Sent from my XT1585 using Tapatalk
 
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