Load check: .357 Mag and AA#9

[Quoheleth]

I'm loading .357 magnum with 158gr LSWC, Tula SPP, and AA#9. Depending on the source, data can either be 13-14.5gr (Lyman), 12.2-13.5 (Lee), or 11.2-12.4 (Accurate's website).

Which set would you trust the most? Accurate, since its their powder? Fwiw, my powder is late 2010 manufacture.

I find it interesting that Lyman keeps going almost 2 full grains past where Accurate stops. I also find it interesting that even with higher charges, Lyman's pressures are similar to Accurate's.

I'll be shooting these in my Smith 66 and GP100.

Q

 

[Josh45]

Different barrels, Different equipment for testing pressure ETC.
You will always have variation when looking up other manuals.

I cannot check your load data since I do not have my manuals with me. How ever, What I usually do is work low at the ladder such as the Powder MFGR charges and work my way up slowly until I see pressure signs for the listed data.

But I don't worry all to much about it either seeing as it comes from a reputable source. Is the bullet the exact same in the Lymans manual as it is in the Powder MFGR site? That can also be why.

 

[788Ham]

I'd suggest using Accurate's load, they are the manuf. of the propellent. THEN, if you want something stouter, you can increase the charge. If you used Lyman's load, as an experiment to go hotter and something went wrong, its too late then! This is why when I buy Hornady's bullets, I'll use their reload book, if I use Speers bullets, I'll use their reload book. They were the ones testing their bullets on their equipment, follow me? You can do as you like, I've reloaded since 1968, never had any problems............

 

[sig220mw]

The differences can vary for several reasons. Climate, how far above or below sea level they are while testing. This is all done by different companies in different parts of the US.

Read your manuals and start with the lowest capacity load or at least close to it for safety's sake.

This is why I have several sources of data.

 

[SHR970]

Lee is regurgitating Accurate's older data. The latest Accurate data V3.5(about a year old) differs from V3.4 data even though they have not changed the powder formulation. This is because they have changed their pressure equipment; you can call them and ask for verification.

Warning this advice is worth what it is costing you. Neither THR or this author assume any responsibility or liabilty for your use of it.

I have used (actually settled on) 13.5 grains of AA#9 for 158 gr. Xtreme plated SWC since the 90's. It worked so well that I even made a dipper to get me that charge weight. I have pushed them harder 9to what is Lyman's max. load) but the accuracy dropped off. I have also used that load level on LSWC at the same weight. I have used this load with Fed., Win, and CCI primers.

Use good sense and practices as you are obviously substituting components. Work up carefully and find where you accuracy is best with your set up. #9 likes to be run harder / closer to max than some powders.

 

[rcmodel]

I also find it interesting that even with higher charges, Lyman's pressures are similar to Accurate's.

You might note that Lyman says the bullet was hard cast with Linotype alloy.
They also told you the bullet mold number w/a picture of it, so you could tell how many grease grooves it has.

You might also note that Accurate or Lee didn't tell you what bullet design, or alloy, or hardness they are even talking about.

rc

 

[Quoheleth]

My Lee discs seem to drop right about 11.4gr, so I'll start there.

Thanks, all.

Q

 

[GP100man]

I get wide EDs when I go below 13grs. shooting Lees 158 RNFP even with mag primers .

I`ve settled on H-110 needs atleast 80% of the case capacity ( from casehead to bullet base) to operate in a consistent way .

I know your inquiry was for AA#9 but it`s a ball powder & they all have similar characteristics , they need pressure to burn consistently .

rcmodel stated why the loads vary so much & I agree ,there`s so many different SWC designs out there they could make a manual for just SWCs for 38/357 calibers !!

Then ya get into test equipment ! pressure proof barrels ,vented barrels ,length of said barrels , actual firearms , then if the CUP system was used or the PSI measurements ???

 

[ArchAngelCD]

I usually trust the bullet company first followed by the powder company.

Remember, a lot of variables cause the differences in load data. The most common are different bullets and different seating depth.

 

[Steve C]

A lot of the differences is load can be from the primer being used. Regardless here is the 158gr LSWC AA9 load I chrono'd from my 4" S&W 66. One of my favorite .357 mag loads producing a little over factory velocity.

 

[Hammerdown77]

I did some load testing with AA#9 and a 158 gr LSWC bullet, BHN 12 from Missouri Bullet Co. Shot for accuracy, haven't run it over the chrono yet.

The most accurate load in all of my .357s was about 12.2 grains, standard small pistol primer. That one feels 357 mag-ish to me, maybe less than the firebreathing Remington 125 grain UMC load, but equal to other Federal and Magtech and Winchester 158 grain standard loads.

This is my "go-to" .357 mag load.

Give 12 to 12.5 a try.

AA#9 does not really behave like H110, in my opinion. AA#9 tolerates downloading well, and I have found my best accuracy under max book loads. Not so with H110, it has a very tight operating window, and best results are usually with a full case.

 

[Clark]

http://www.thehighroad.org/showthread.php?t=609375&highlight=AA#9

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

From my notes about loading an S&W 60 I reamed out from 38sp to 357 mag and my Colt Police Positive I reamed out from 38 sp to 357 mag.

"Midway Load Map" says max 357 mag load is 13 gr. AA#9 158 gr. JHP.

"Lyman 47th" says 16 gr.

I did 17 gr. and the case stuck bad.

357 mag SAAMI limits were reduced when thin walled chambers came along and sticky cases resulted with factory ammo.
The correct max load for 357 mag, should be one that the cases are always easy to extract.