Load data differences for 357 mag

[K1mber45]

I was taking a look at the load data for .357 HDY XTP 158gr. with Accurate #9 in the Hornady reloading book and Accurate's website and noticed a huge difference.

Hornady book shows a 11.9 max load but the Accurate website shows starting 12.4 with a max of 13.8... what gives?

[Doodlebugger45]

Wow. That's a big difference and an even bigger difference from what my personal loading log shows. I'll have to research where I found the load data now, but I show that I shot 14.0 gr of AA#9 with a Hornady JHP 158 gr bullet, CCI small magnum primer. My shooting notes say that it exceptionally accurate, no soot at all, and moderate recoil in my Blackhawk. The day was only about 25 degrees though, so maybe the cool temp kept the pressure sort of low. I also shot some hard cast loads with 12.6 gr of #9 that day with a 158 gr Chey Cast bullet. The log shows no fouling, no leading, and great accuracy. I remember shooting those loads that day. They might be the best stuff I have found for hot loads. I didn't make any mention at all of difficult extraction or any other high pressure signs.

[rg1]

My favorite load with AA#9 with Hornady's 158 XTP is using 13.0 grains of AA#9 with a standard CCI 300 primer. AA tested with the standard primer in their no.1 manual and used a magnum Winchester primer in manual no. 2 and on their web site. I think AA's data is more realistic and at 13.0 grains it shows no pressure in my 6" barreled revolver and my Marlin carbine and is very accurate. I've tested at 13.0 grains in various cases.

[89blazin]

I'll pull out my database of over 22,000 loads and see what is documented in there.

[mrbro]

Lyman #48 has that bullet in a Federal case over a CCI 550 primer. Start is at 13.4g for 1158fps at 32900CUP, max is at 14.9g for 1279fps at 41800CUP. I like the Lyman data because they report the pressure for many of their loads.

[Clark]

2000 Accurate Arms Reloader's Guide 357 mag 158 gr XTP 13.5 gr 6" 1216 fps
2001 Accurate Arms Reloader's Guide 357 mag 158 gr XTP 15.0 gr 6" 1633 fps
2011 Accurate Arms Reloader's Guide 357 mag 158 gr XTP 13.8 gr 6" 1367 fps

http://www.accuratepowder.com/wp-con...d_data_3.5.pdf

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

From my load notes:

5) Accurate Arms max load for AA#9, 158 gr.
357 mag, 1994-2000, 13.5 gr.
357 mag, 2001, 15 gr.

a) Colt Police Positive 38 special
16.7 gr., ok
17 gr., cases stick

John Bercovitz Feb 11, 1993
http://groups.google.com/group/rec.g...02ce69fa01e631

..you can see that if a chamber's
walls are particularly thin, it will be hard to extract cases (regardless
of whether or not these thin chamber walls are within their stress limits).
A really good illustration of this can be found when comparing the S&W
model 19 to the S&W model 27. Both guns are 357 magnum caliber and both
can take full-pressure loads without bursting. The model 27 has thick
chamber walls and the model 19 has thin chamber walls. Cartridge cases
which contained full-pressure loads are easily extracted from a model 27
but they have to be pounded out of a model 19. So manufacturers don't
manufacture full-pressure loads for the 357 magnums anymore. 8-(

What does it all mean?
357 mag loads are driven by the threshold of cases sticking, but when that gets balled up by load books, look out.

[K1mber45]

Here are the two sources, the Hornady book is the latest one released in December 2010 and the Accurate info was pulled off the site moments ago. Why would the Hornady book be so conservative?

[wncchester]

"Hornady book shows a 11.9 max load but the Accurate website shows starting 12.4 with a max of 13.8... what gives? "

Yeah. That sorta stuff happens.

Tends to undercut a feller's faith in the inerrancy of loading manuals, don't it? I mean, all but that part where they tell us to "start low, work up slowly to max unless you see signs of excess pressure, etc,"; they ALL agree on that point.

[Clark]

K1mber45 Why would the Hornady book be so conservative?

That is like asking why Julia Child has less sugar in her cookies than Betty Crocker.

Load books are only loosely tied to reality.

[buck460XVR]

Why would the Hornady book be so conservative?

The max Accurate load lists pressure as above the SAAMI max of 35,000psi. I assume the Hornady max load is below.

[joneb]

I've loaded Hornady 158gr XTPs with 13.2-13.9gr of AA#9 with SPPs and SPMPs for years without any trouble in a Colt Trooper .357 and a Ruger Sec. six, the hotter loads were shot in the Ruger.

This powder/bullet combination has work very well for me, but I did have sticky cases and flattened cratered primers at 12.5-12.8gr with AA#9

AA#9 has also given me excellent results with 180gr hornady XTPs useing 12.6-12.9gr with SPPs and SPMPs

[89blazin]

For your application, the data I have from Accurate Arms is 15gr. max @ 1.58 OAL.

[Utahar15]

I have a question. I was also doing some research from different manuals and using a 158 round noise lead bullet I see the range starting as low as 2.8 of unique and going as hight as 4.5, now this is 38 Special. I've looked in 6 different manuals and get 6 different loads.

My question is for the new reloader what manual to you trust? I mean one said a starting load of 2.8 one said 3.1, 3.3 and two says 4.0. Now 2.8 to 4.0 is difference, now if 2 the Lyman 49th as well as the Lee 2nd tells me a starting of 4.0 and I think it was Speer's 13 tells me 2.8 what manual should I follow?

How much under minimum load will not even give the power to push the bullet out the barrel?

I have a 1.78 inch 38 Special and a 4" 357. This is getting confusing. Sometimes I wonder if the one manual approach would be best.

Robb

[SL1]

I don't have all 3 of the Accurate Manuals that Clark references, but the one I do have showes that they shot the data with the CUP measurement method, which has a SAAMI pressure limit of 45,000 CUP. The pressure that Accurate showes for 15.0 grains of #9 powder is 44,900 CUP. There really isn't any agreed-to conversion from CUP to PSI, but a reasonable guess is that 45,000 CUP in a .357 Magnum cartridge is a little over 45,000 psi.

On the other hand, the Hornady data was probably produced with the PSI measurement system. SAAMI adopted a maximum pressure of only 35,000 PSI for that system, and loads and velocities with the newer system are obvious reductions from what was obtained with the old CUP system. For what it is worth, my older Hornady #4 manual lists 14.3 grains at the top end of its chart, and that was probably shot with the CUP system. And, Hornady's charge vs velocity tabular format only tells us that 14.3 grains produces 1450 psi and that the next increment that would produce 1500 fps is not recommended. Extrapolating the #4 data would indicate that something like 14.7 or 14.8 grains would have produced their 1500 fps table entry, so that is still a little lower than the Accurate max at 15.0 grains. But, it is a lot closer.

That is why I think you have data from two different sourcse that are using different measurement systems and different pressure limits, rather than just seeing the usual effects of different lots of powder, etc.

Note that the SAAMI pressure limits for the 44 Magnum were similarly reduced in the PSI system.

SL1

[buck460XVR]

I don't have all 3 of the Accurate Manuals that Clark references, but the one I do have showes that they shot the data with the CUP measurement method, which has a SAAMI pressure limit of 45,000 CUP. The pressure that Accurate showes for 15.0 grains of #9 powder is 44,900 CUP. There really isn't any agreed-to conversion from CUP to PSI, but a reasonable guess is that 45,000 CUP in a .357 Magnum cartridge is a little over 45,000 psi

The pressure I quoted is listed on the Accurate web site as PSI....not CUP. Their pressure listed as 35,022 PSI with their max load, while only a tad over SAAMI specs is still that, over. Their tests are also done with a 6'' test barrel. I believe Hornady uses a Python with a 8'' barrel. While the Accurate load may be safe in a 6'' test barrel, I would never shoot it in a Python......just sayin'. With the many uncontrollable variables in handloading(i.e. scale accuracy, seating depth variance and firearm), in today's lawsuit happy society, I'm surprised anyone suggests a max load over SAAMI specs. Folks need to look at more than just the max load recipe when deciding what is safe in their gun. That is why I always suggest at least 3 different sources of reference before attempting development of a new load.

[mrbro]

C.U.P to PSI
If there is a relationship between these 2 standards you will not find it looking at the SAAMI maximum ratings for each cartridge. Reviewing the published spec some ratings stayed the same, some PSIs are higher than the CUP and some are lower. It appears that SAAMI either took a number of factors into account when making the new standards, or there other idiosyncracies with the test procedures that come into play.

Hornady Data
In my 4th edition of the manual, vol 1 page 74 describes the test methods. In that edition, to establish maximum loads, they used CUP when a test barrel was available, otherwise they read the signs on the primers and cases during load development. The actual load data came from chrono tests using the weapon listed for the caliber.

The 357 data in the 4th edition lists a max for AA#9 as 14.3g over a Fed 200 primer in a Hornady/Frontier case. Since this corresponds with the Lyman data and meets the standard that was in effect for over 50 years for that cartridge, I'd be comfortable with it as a maximum.

[Clark]

The important thing to me is not that load books missed the SAAMI registered mark for 357 mag, but the both SAAMI registered pressure missed the 357 mag mark, and load books missed the SAAMI mark.... error on top of error.

SAAMI should be the threshold of 357 mag cases get sticky, backed of by the equivalent of 6% powder charge, and expressed in pressure.

Load books should all reflect the same pressure.

Then a hand loader should be able to take any 357 mag max book load, increase the charge ~6%, and find the threshold of sticky cases.... The published load should have been 16 gr AA#9 for 158 gr in all load books.

That is the standard to which we should hold SAAMI and load books.

But we should be sorely disappointed by what we got instead.

[WESHOOT2]

I trust NO book; I start low and work up.
THAT I trust.

I start low and work up.