High Extreme Spread with AA#9 in 357 magnum

[Stormin.40]

I tested some 357 magnum load over the chrony the other day and was disappointed with the extreme spread. I used Standard Small Pistol Primers, should I have used Magnum with AA#9? I know the amount of crimp can effect this as well, I crimped as firm as I felt comfortable with without crushing the case, used RCBS roll crimp die. Seat and crimp in separate steps, cases were not trimed.

158gr Hornady XTP with AA#9, 13.4gr (ES 102), 13.6gr (ES 114), & 13.8gr (ES 76). Velocity gain from 13.4-13.8 was only 10fps given 13.8gr is max per Accurate Arms load data I expect I have reached the top end load.

The A2400 loads I checked the same day, 13.9gr and 14.3gr, were a little better but still had ES at 66 & 72.

I need work on more load development but was wondering if I should test with magnum primers? I am using a 4" S&W 586.

 

[Walkalong]

I haven't had particular good ES numbers with A #9 in .357 either. Great ES numbers with it in .41 & .44 Mag though. Go figure. I haven't tried any Mag SP primers, so I can't say about that.

 

[627PCFan]

My preferred load is a 158gn XTP over 13.8gns of AA9. Im getting an ES of 32 with a 627. Try trimming cases to get rid of work hardened brass at the crimp point, I bet your groups and ES shrink. Also, just curious what your velocities were with a 4incher.

 

[Stormin.40]

6 shot average velocity

Hornady 158gr XTP
AA#9 13.4gr 1260fps
AA#9 13.6gr 1262fps
AA#9 13.8gr 1269fps
A2400 13.9gr 1138fps
A2400 14.3gr 1142fps

Hard Cast 158gr SWC
A2400 14.0gr 1182fps

 

[rg1]

I use standard CCI 500's with AA#9 in RP cases mostly and Hornady 158 gr. XTP's. A few loads I did test got lower extreme spreads with standard rather than magnum primers. My load is 13.0 grains and I shoot them in a 6" revolver and a Marlin rifle and with AA#9 I'm pleased with the accuracy in both. Present Accurate Arms data tested with a Win SP Magnum primer but in their 1st reloading manual they tested with CCI 500's. In their 1st edition manual 13.0 was their top load at 1261 fps and 34000 psi in a 6" SW revolver. The oal in the 1st was 1.580".

 

[41 Mag]

I have fond that trying to get low ES while loading for revolvers is not really worth the effort. When working with rifles, and shooting for groups measured in 10ths or less of an inch, yes.

I use AA powders quite a bit both with jacketed and cast, and my 160gr cast HP load is 13grs. It might not get low ES I haven't bothered to worry about it, but it will shoot a ragged hole at 25yds offhand.

The crimp will help and I use as little as I can get away with making sure the case has a tight grip on the bullet. I usually load up a full cylinder, shoot 5 of them and measure the 6th one after each previous shot. If it holds I load up 5 more and repeat. If it moves, I adjust the crimp to just a touch more and repeat. This usually results in both the proper crimp to hold the bullet in place and also give enough overll tension to fully ignite the powder.

I more times than not use Win primers, but have also use CCI as well. I switch back and forth between the mag and standards as most of the time I do not find the mag producing anything better with my groups. That said they might help out with better burns, but I would only use them with a powder like 110/296 where you need the extra boost to light things off.

 

[huntershooter]

With AA9 in magnum revolvers, with less than maximum loads I have used magnum primers.
With moderate loadings (which I use a lot) I experienced crazy extreme spreads, a lot of powder residue and hangfires on occasion (this in .44 mag and .45 Colt +P).
I suggest trying magnum primers.

 

[GJgo]

I also only use mag primers with AA9 in a few different cartridges including 357. That powder is very dense, it does not compress.

 

[murf]

what brand of primer are you using?

how much case neck tension are you using?

are your loads accurate enough for you? like 41 mag stated, low a low extreme spread does not mean better accuracy.

murf

 

[Stormin.40]

I used Winchester Small Pistol primers. The loads are accurate enough for me, I can't shoot well enough to notice off hand. I have a good crimp, as firm as I feel comfortable without crushing or buldging the case.

 

[murf]

stormin.40,

you shouldn't need a mag primer with those two powders, but you may want to try another non-mag primer anyway.

the cannelure on the xtp bullets is rather shallow, so crimping to the bottom of it is about all you can do. i asked about case neck tension because that is the other thing that holds the bullet in place and, in my opinion, is much more important.

you can measure the neck tension on your cartridges using a dial caliper. measure the outside diameter of the case just below the mouth and a bit below the bullet base (there should be a bulge in the case at the bullet base). the difference is your neck tension.

the more tension the better for your load.

also, make sure your bullet isn't pulling out of the case from recoil. load six, shoot five, then measure the col of the sixth round. should be the same length before firing and after. if it is not, you will need more case neck tension on those bullets.

murf

 

[Stormin.40]

Thanks Murf, I will check the neck tension, there is a slight bulge. The powder is burning clean which I think means it is burning completely.

As others have stated it seems high ES number don't necessarily mean bad accuracy. I need to do more accuracy testing to see in my case.

 

[bluetopper]

Keep in mind you're using a 4" barrel, your velocity spreads will decrease with a longer barrel and more complete burning. Plus no discernible accuracy difference. Nothing in the world wrong with #9 powder.

I wouldn't worry about it one single bit.

 

[Slamfire]

Don't worry about it, pistols, particularly magnums, have wide extreme spreads. Just fret about sight alignment and trigger pull, and if you get those right, the rest will follow.

I have measured high ES's with all my magnum powders in the 357.

[SIZE="3"]Smith & Wesson M27-2 6.5" barrel		
				
158 LRN Valiant 12.0 grs AA#9 CCI500 Mixed cases 	
				
Ave Vel =1278		 	
Std Dev =34.98			
ES  =	117.4		
High  =	1344		
Low  =	1226			
 N =	27			
				
				
158 LRN Valiant 12.5 grs AA#9 CCI500 3-D  cases 	
				
Ave Vel =1348		 	
Std Dev =34.16		
ES  =	134.7		
High  =	1386			
Low  =	1251			
 N =	25			
				
158 LRN Valiant 13.0 grs AA#9 CCI500 3-D cases 	
				
Ave Vel =1360		 	
Std Dev =33.19		
ES  =	109.8		
High  =	1393			
Low  =	1284			
 N =	26			
				
158 JHP (W/W) 13.5 grains 2400 R-P cases WSP	
				
Ave Vel =1196		 	
Std Dev =26.58			
ES  =	87.17			
High  =	1244			
Low  =	1157			
 N =	10			
				
158 LSWC Linotype Bullets 12.0 AA#9 Mixed cases CCI500 
	 			
21 June 2008 T =  85 °F			
				
Ave Vel =	1166			
Std Dev =	99			
ES =	251.8			
High =	1245			
Low =	993.3			
N =	6			
				
				
				
158 LSWC Linotype Bullets 15.5 W296  Zero Cases CCI500 
	 			
21 June 2008 T =  85 °F			
				
Ave Vel =1282			
Std Dev =35			
ES =	128.1			
High =	1325			
Low =	1197			
N =	12			
				
	
				
158 LSWC Bullets 15.5 W296  3D Cases CCI500 
	 			
14 Oct 2008 T =  80 °F			
				
Ave Vel =1260			
Std Dev =34			
ES =	160.5			
High =	1315			
Low =	1154			
N =	18			
				
				
158 LSWC Linotype Bullets 12.0 AA#9 Mixed cases CCI500 
	 			
14 Oct 2008 T =  80 °F			
				
Ave Vel =1217			
Std Dev =52			
ES =	224.9			
High =	1346			
Low =	1121			
N =	29			
 
[/SIZE]

 

[john wall]

I have loaded #9 since it came out. Max loads, heavy bullet pull, and standard weights give great results. Not a powder for reduced loads.

There may be faster powders, but I think #9 is the best of them all for magnum handgun rounds. I don't use magnum primers.

I have used 13.5 gr in the 2 1/2" 410 with great results on the clay target range. I am sure it will serve well in the 300 Blackout.