AA#9 and Winchester mag primer for .357 mag

[496rathead]

Is a small magnum pistol primer needed for AA#9 powder in a .357 mag?
I use Winchester primers. I have both magnum and non-magnum primers.

I shoot 125's, 140's, and 158 grain jacketed bullets, by speer, hornady, and sierra.

Thanks

[Teuthis]

Research your question in the reloading manuals. Find the recipes that use AA#9 for the bullet you are using in .357, determine what primers are being used and do likewise. If you cannot do that simple task, you should not be loading ammunition.

[jepp2]

A quick check of my Sierra and Lyman manuals both show CCI 550 (small pistol magnum) primers for all powders listed. Some loads listed AA #9 powder, some didn't.

[496rathead]

My hornady and sierra manuals use the mag primer, but my speer manual says to use only a mag primer with H110 or W296 or excessive pressures might result.

I found it odd that speer reccommends a mag primer only for H110 and w296

Thanks

[AlaskaMike]

There's two philosophies that I've come across as to whether you should use mag primers or not. One says that if the cartridge is considered a "magnum", then a magnum primer should be used regardless. The other philosophy says that you should use a magnum primer only if the powder is of a certain type--ie, some ball powders.

I tend to follow the second philosophy. My .357 mag loads using 231 and Power Pistol get standard primers, and my 296 loads get mag primers.

As for your original question of whether mag primers are needed with AA9, I can't answer that one since I've not used it and don't have access to my manuals right now. You could try both and see what your gun likes better. One important note if you try that--cut your load by 10% when you replace the standard primer with the mag primer, and then work up from there. For example, if you start out by loading 14 grains of powder with standard primers, and then drop the charge to 12.6 (14 - 1.4 = 12.6) grains with mag primers. A 10% drop in charge weight is probably more than necessary but when you start doing stuff like this (going outside the recommendations of published load data) you need to be extremely careful and keep a generous safety margin.

Good luck,
Mike

[rg1]

Accurate Arms manual #1 used CCI 500 small pistol primers in their data for the .357 Mag with AA#9. They also tested CCI 300 large pistol primers with AA#9 in .44 mag. I load .357 Mag with CCI 500 small pistol primers in rifle and pistol. A magnum primer is not needed for AA#9 powder.

[joneb]

I have had very good results with AA#9 using CCI 500 and WSP for .357 Mag for 158gr and up, but for bullet weights below 140gr I would try magnum primers and compare.

[Sport45]

I load all my mag cases with mag primers without regard to the powder I intend to use. That way, if I decide I don't like a load I can pull the bullets and refill the case with any powder I want.

When you see a load book that lists mag primers for everything in a mag cartridge that's probably what they are doing too. The technician may be sitting at a bench with a pile of primed brass and just works up different powders until he gets to max pressure.

[English Bob]

On page 44:

"In our tests we have found no significant effect on performance using magnum primers- with one exception. Winchester Small Pistol Magnum primers are significantly more powerful than most small rifle primers. If you use this primer in handgun loads with our propellants, DO NOT EXCEED the listed START CHARGE in the Loading Guide. Our tests with Accurate No. 9 powder indicate that this particular primer can raise pressures as much as 35%. This primer has a specific use and is not necessary or recommended for handloading Accurate propellants."

[Mac1045]

ALWAYS USE Mag primers with AA9 or any other slow powder. AA9 is a re work of WC820 Military powder for the 30 carbine. It must have a mag primer, especially if you are shooting in cold weather. I have been a commercial reloader for 30 yrs, and have used WC820 labled many ways by several powder companies. It is the best powder avail for high velocity pistol loads. Use a tight crimp also.

[stang68]

Seems that everyone has their own opinion on this. I'm fairly new to reloading so I tend to follow what is recommended in Lee Modern Reloading, 2nd edition, pg. 205, in which he says to "use standard primers for all powders except Winchester 296". Unless I find out that I'm not interpreting that correctly or if I get bad results with standard primers with Accurate #9 (when I can find some), that's what I'm going to do. I am aware that on the Accurate Arms website they say to use magnum primers. As I said, everyone has their own opinion.

[Sport45]

"use standard primers for all powders except Winchester 296".

What are you going to use with H110?

It's the same stuff as W296....

[stang68]

I think it's obvious based on the info you provided.

[Sport45]

But if I hadn't posted that you wouldn't have known. The point is W296 is not the only powder that requires or has it's performance improved by magnum primers.

If Accurate Arms says to use magnum primers with this powder that's what I'd do. After all, they should know.

Oh yeah, Welcome to The Firing Line!

[stang68]

Thanks for the Welcome and the info Sport45. I guess the only point that I was trying to make is that this topic is in the Reloading section of just about every Gun forum and the opinions seem to be about equally divided, and as I stated even Richard Lee seems to have an opinion different from that of the powder companies. I was just stating my opinion. You know what they say, "Opinions are like xxxxxxxx, everybody has one"

[ccchas]

This thread is a few years old now but since www searches examine these notes I wanted to share my recent experience shooting a Dan Wesson 357 Max "Super Mag" revolver.

My trial loading for 357 Maximum with a 180g JFP bullet using A#9 powder and Winchester small pistol magnum primers was unexpectedly too hot. The cartridges were stuck in the cylinders (a tap with a punch removed them) and the primers were flattened with signs of melting around the firing pin.

The load was about 10% under the published maximum for A#9 with that bullet. Apparently the Win mag primers were just too hot. My other trial loads using Lil'Gun and 2400 at sub maximum charges with Win mag primers did not show that over pressure.

I'll try backing off the load and also switching to small rifle primers which are recommended for 357 Max to better handle the pressure.

I don't know whether A#9 with Win mag primers in regular 357 Mag full magnum loads would experience a similar over pressure. I'm posting this 357 Max experience just in case it might be relevant.

[Clark]

AA#9 is a slow ball powder.
125 gr is a light bullet.

Given that, magnum primers might seem to be necessary, but the roll crimp will have bigger effect.

AA#9 is actually easy to ignite, an reduced loads are possible.

[vladan]

No need for mag primer. I load 125grains Montana Gold JHP over 16grains of AA#9 with Wolf SP. One of two most accurate loads from my GP100

[joneb]

I found AA#9 did not down load well with standard primers in .357 mag.
Accurate's guide using CCI 500, 158gr XTP 13.5-15.0gr of AA#9
Hornady's using Fed 200, 158gr XTP 12.0-14.3gr of AA#9
I loaded Rem. 158 JHP with CCI 500 and 12.5gr of AA#9, I had flattened cratered primers and stuck cases. I then tried 13.2gr and the primers looked normal and the shell cases fell from cylinder. I settled at 13.7 gr with this bullet, the load was very accurate.

[escard]

I once made a primer-check for a concrete load using a (near max) charge of AA #9, 140 grs XTP and I got the very best accuracy results using Remington 7,5 primers (=small rifle primer!).
while the loading with the 7,5 primer shot better than all the other loadings (cci-550, fed 155) in the Single-Action mode, I had on the other side to turn the trigger-screw in to make a heftier slash to guarantee the revolver punches the thicker primer cup hard enough to fire it in the DA-mode.....
The tryings with the 7,5 where a lucky number because I did it only because I had some left primers from some casull-testing..........

[MR 8x57js]

Accurate does not use a mangum primer in there loading data! H-110/296 or even IMR-4227 needs a magnum primer