AA#9 Unburned Powder & Crimp


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BBDartCA
August 29, 2011, 09:49 AM
Recently shot about 30 different 357 reload recipes at the range and noticed the AA#9 usually left traces of unburned powder in the shell case and cylinder. On the range bench where I was shooting, there was also a pretty big pile of unburned powder dust on the bench. Many times while shooting I could feel a "dust storm" of powder spray my off hand.

All of these loads were with and without mag primers for a given bullet weight and charge amount. I also shot a number of different recipes with IMR4227 and W231 and these left no apparent unburned powder.

I now notice in an old AA reload handbook, it says AA#9 should be used with a heavy roll crimp, especially with heavy lead bullets. Will the heavy roll crimp help with the unburned powder? I use a Lee FCD and had these set on the light side of the crimp (1/2 turn in setting). I'm assuming the heavy crimp can allow the case to build more pressure and thereby burn the powder charge more completely. If this is the case, I'm wondering if AA #9 is a bad choice for plated bullets due to the sometimes difficulty of applying a heavy crimp. It will be a few weeks before I can make some new loads and test them.

With all three powders, I shot a variety of different charge amounts and primer combos with 125g FP plated Berry's, 125g XTP, 158g XTP, 125g Remington hollow points and 158g FP plated Berry's. As an aside, it seemed the best accuarcy was with max load of 4227 with 125g Remington hollow points. Firearm was 6" Dan Wesson.

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627PCFan
August 29, 2011, 10:07 AM
I dont get any unburned powder with 180 RNL (MBC's), but i do get some from the 158 SWC (MBC's), though Im not concerned about it. AA9 is for the heavy bullets. A good crimp is necessary to get things going, but ultimately the bullet weight/resistance is what causes pressures up and a complete burn.
Im a fan of the 4227 in the 125 grain jacketed too.

SlamFire1
August 29, 2011, 10:58 AM
I shot a bunch of 158 LSWC's with AA#9 in the 357.

Yes I got unburnt powder.

But I also got unburnt powder with H110/W296 and 2400.

I eject my my fired cases into a container on the bench. No matter what primer/powder combination I use, I always have unburnt powder in that container after I fish the cases out.

Walkalong
August 29, 2011, 11:58 AM
Same here in .357, but it burns much cleaner and more completely in .44 Mag. Go figure.

gamestalker
August 29, 2011, 12:29 PM
I'm exclusive with H110 or 296 with CCI mag. primers for both .357 and .44 mag. and I'm not seeing any indications of an inefficient powder burn. I did however experience this with a standard primer rather than a magnum primer. It was back when things were difficult to find so I decided to go with a standard primer not thinking it would really make a major difference.
Where are you in terms of the powder charge, at the upper end or lower end of the data? Some powders don't perform very well at the lower end of the data.

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