The following is a summing up of the investigation I did for a particular load when I found some distinct conflicts in the data I have available. Since this can be rather common anytime you have more than on load guide I thought it might be helpful for others facing the same issues.

Specifically a 125 grain Hornady XTP-FP over H-110. Being a bit OCD and a bit cautious naturally has me looking at various Data Tables any time I am trying out a new powder or load. The problem here is that there is a WIDE variance in load recommendations for this powder.

Hornady say's 17.4 start/19.9 max with a 125 grain jacketed XTP bullet. Velocity range given is 1250 start/1500 max. No pressures are listed and the testing was conducted with an 8 inch Colt Python.

Speer 14 says 18.0 start/20.0 max for H 110 with a 125 grain jacketed bullet. Velocity range given is 1154 start and 1282 max. No pressures are listed for any of the data and the testing was conducted using a 6 inch S&W model 19.

Lyman 49 says 21.0 start/22.0 max for H 110 with a 125 grain jacketed Hornady XTP-HP. Velocity range given is 1357 start and 1506 max. Pressures listed are 33,500 CUP start and 42,600 CUP max. Testing was conducted using a 4 inch barrel on a universal receiver with no mention of it being vented.

Hodgdon says 21.0 start/22.0 max for H 110 with a 125 grain jacketed Hornady XTP. Velocity range given is 1881 start and 1966 max. Pressure listed is at max only at 41,400 CUP. Barrel length for testing is listed as 10 inches which happens to be a standard TC Contender Barrel.

Lyman 49 TC Contender data with a 10 inch barrel lists 21.0 start.22.0 max with a 125 grain Hornady XTP-FP. Velocity given is 1907 start and 2019 max, rather supporting of my assumption that a 10 " TC Contender was used for Hodgdon's data. Pressure with this loading is not listed.

So, we have Hornady being the lowball at an 17.4/19.9 load range producing velocities which can be viewed as rather conservative for a 125 grain 357 Magnum from an 8 inch Python. We also have Speer 14 at a corresponding range and a velocity that corresponds well if you take in the 6 inch barrel instead of 8 inches. So, Hornady and Speer pretty much fall into the same range but neither tested for pressure and both are producing velocities which might be viewed as rather conservative for a 125 grain bullet in a 357 Magnum. To be honest I'd like a load that produced around 1400 fps in a 4 inch revolver.

So, perhaps it's time to step up to the load levels in the Lyman 49 and Hodgdons data. However the pressures given as high as 42,600 CUP had me taking a second look into that data. Because the current SAAMI maximum for 357 Magnum is 35,000 CUP and my prior exposure to cup was with rifle loads such as the 308W which sometimes list maximums for this caliber as 52,000 CUP/60,000 PSI. That had me making the assumption that the pressures for the Hodgdon and Lyman data were probably in the range of 45,000 psi, way over the SAAMI maximum.

That had me doing a bit more digging and I managed to located a PDF for the 1993 SAAMI/ANSI specifications, a 162 page manual for the specifications and testing methods for all of the SAAMI centerfire handgun and rifle loadings. Pages 11-12 list handgun load specs in CUP with velocity and bullet types using 4 inch vented and 10 inch unvented barrels. Pages 15-16 list the exact same data with the pressures given in PSI. So, for handgun loads the SAAMI maximum in CUP is actually 45,000 and in PSI it's 35,000. In addition a velocity of 1425 fps will be produced with a 125 grain bullet operating at the SAAMI maximum from a 4 inch vented barrel. That same bullet will also produce a velocity of 1875 fps out of a 10 inch unvented barrel at the SAAMI maximum.

My conclusion is this. First, both Hornady and Speer are listing loads that can be viewed as a bit "lawyered up". In simple terms they are conservative because testing for pressure wasn't done. When you are guessing on the produced pressure is far safer to take a conservative approach and I won't fault Speer or Hornady for doing this. In this case, and likely this Caliber, the manual that is the most accurate is the Lyman manual with Hodgdon's data being comparable with the exception of the hyping of the produced velocities due to the excessively long barrel used in the test. As a result my first loads will start out at 21.0 grains and I'll see how they shoot.

Thank you for this work. I find it very aggravating to bounce from manual to manual trying to sort out the wide variance in loads. A chronograph has helped immensely, but I will now start with the Lyman book and work out the load from there. Thanks again!

Speaking just to the non-Contender loads, the variance isn't that great when you factor in the different barrel lengths. It's hard to tell which guide is more "accurate" without chronoing the loads yourself, using the same variables. Hornady and Speer and others often don't publish pressure test results. But that doesn't mean they didn't test for pressure. This only means, to me, that pressure was within safe limits for the loads tested. My limited chrono testing over the years corroborates Speer, Lyman and Sierra results.

Regarding the Contender loads, yes, you're going to see heavier loads and higher speeds. Run out of rifle barrels there is an even greater gain.

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USAF, 69-92
Vietnam, 72-73

I have always considered the data/results in my reloading manuals to be the findings of a particular technician, using the specified powders, primers, and test equipment, on a particular day. Not hard and fast formula. Too many differences in powder lots, specific bullets, primers by manufacturer and lots, and test equipment/methods for the results not to differ from manual to manual.

You mentioned a 6" S&W Mod. 19, an 8" Colt Python, a 4" Universal Receiver, and a 10" Contender. So, different results will be reported just for the fact that at least 4 different test fixtures/guns were used.

I understand the researching/digging for facts where it pertains to our hobby. I also compared pressures, and load data in maybe 8 manuals (I wasn't satisfied with the info I got from 4 manuals so I bought 4 more!). I think it's all part of the fun of reloading...

Thanks for your post.

You are going to work the load up anyway right? SO start with low avg data & work it up to avg max. In revolvers, despite what some think, you can see pressure signs, watch for them.

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NRA Cert. Inst. IDPA CSO

Hornady and Speer are notoriously conservative when it comes to H110/W296 and centerfire handgun. Lyman and Hodgdon just the opposite. Don't make either of them wrong, just different. Too many folks focus too much on published velocities and not enough on how the round actually performs outta their firearm for reliability and accuracy. One reason I always try to source three or more references for load data when starting with new components or platform is because of the variances between manuals. I avoid the extreme highs and lows and start at a median start load and work up till I find the most accurate load. Many times I don't even chrono the load till I find which one is most accurate unless I'm gettin' up towards the max. I ain't tryin' to win a race, just hit the target everytime.

Hate to tweak your OCD any further than it is. BUT unless the SAAMI spec document that you refer to lists the bullet, brass, primer and powder by maker, name and lot number and the seating depth and crimp pressure all you have is another single example of load data just like the various manuals. The only advantage is that it is not "lawyered" up with "recommended" min and max loads.
In this incidence the Lyman manual more closely matched the gathered data. To believe that will always be true for every load in every caliber is probably unwise.
A chronograph is a very small investment for your peace of mind and there are places where you can send some of your loaded rounds to have YOUR loads pressure tested.
OR just forget about loading MAX loads and enjoy your shooting with milder loads. I know my wrists wish I had done just that many years ago but it is too late now that 50 plus years of all the un-needed recoil has taken it's toll.
Chip King

Chipking, I wasn't trying to state that there wasn't any indication that a particular load manual was the most accurate, simply my approach to determining what data it this particular case I felt was the most accurate. My intent was to illustrate my approach to resolving conflicting data in the hopes that some might find it useful.

BTW, the deciding factor in this case was the SAAMI/ANSI results for the 357 Magnum operating at maximum pressure using a 4 inch vented barrel. These results are in line with what I would expect for a 125 grain jacketed bullet in this caliber and the data that best corresponded to this was that provided by Lyman.

I also want to make it clear that it's just in this particular case where Lyman had what I felt was the most accurate data. In previous experience with the 40 S&W and the 45 ACP I've determined that the data provided in the Lyman 49 is rather conservative and Speer 14 has it pretty well right.

Basically, anytime you work on a new load it's safest to use as many sources you can find and when you see a trend that is the direction to follow.

"lawyered up"...................loads work in my guns.

When I was young maximum loads were the thing.........
but after killing a M19 I learned something.
There are high velocity loads and also loads that still shoot very accurate at lower speeds and are easier on you and your gun.

1450 fps is a nice 125gr Xtp loading ...........

Some of my friends squeak out all they can get but their cases don't last too long......... just a matter of what makes your whistle blow.

How are you determining what data is "conservative" or "pretty well right"? Are you using a chrono?

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USAF, 69-92
Vietnam, 72-73

Also note that H-110 is very dangerous at less than minimum loads! Loading H-110 below minimum can cause internal explosions, without the projectile exiting the gun. It is for this reason that I use 2400 for magnum loads. Much more forgiving and a much wider min/max than H-110.

G

Just another thought; engineers can determine what's best for a particular application on paper. Many times the "theoretical" findings won't work optimally in real life where all variables come into play. For example, when I was a machinist, the company engineers specified a particular tool, and work speeds to produce a specific machined part. Theoretically, the specs. (book info.) should work, but rarely did. Pressures and accuracy can be determined on paper (in theory) but many times are way off in real life situations...

Which is why one needs a chrono to test a given load in a given gun. Extrapolation and data comparison are good starting points, but empirical real life chrono testing is the bottom line.

__________________
USAF, 69-92
Vietnam, 72-73

No doubt that a chronograph can do a lot of confirm a load is working as expected and if it were May to mid October I'd be heading up north this weekend to do some load testing. However, right now the temps are in the 20's and prior experience with my Shooting Chrony LED skyscreens has demonstrated that they don't work anywhere near as well as advertized. Basically, they don't work worth a damn at an indoor range with florescent lighting because the LED's are UNDERPOWERED. So, I'm not going to drive 40 miles to sit shivvering my backside off and will use feel and observation of the fired cases to determine if these loads are a bit too energetic. BTW, since my load is at Lyman's starting point I rather doubt that I'm pushing any limits. Next spring when it warms up I'll chronograph this load and see how it works.

So, tried out the new load today. Specifically 21.0 and 21.3 grain of H110 in combination with a 125 grain Hornady XTP-FP, a CCI 550 Small Pistol Magnum primer, an overall length of 1.590 inch in a Federal casing.

I will now dub this load to be named Holy Muzzle Flash Batman, I can't see a thing and my ears are ringing. In the shortened version it's the HMFB 357 Magnum. It's a good thing the range owner put me in the rear range usually reserved for local LEO officers doing some practice. Because the main range had a bunch of new shooters who couldn't even make it to their assigned lane. I hate to think what might have happened from all those new shooters flinching every time I set one off. It is every bit as loud as a full power 44 Magnum and the muzzle flash is slightly blinding at a moderately well lit indoor range. Hindsight tells me that H110 isn't a good choice for use with a bullet this light, so I'll probably reserve the rest of my H110 until I can find some 158 grain XTP's.

On a positive note those XTP's did stay together well and I wasn't hit by any debris. Far better than the Blazer Brass 357 Magnums that I shot after finishing up with my custom load. Speer is loading the Blazer with a 158 grain plated HP and those bullets were coming apart and pelting me with debris at least 30% of the time.

More good news is that IMO Lyman's data is pretty accurate. From the snap of the recoil I would estimate velocity was in excess of 1300 fps and muzzle energy was in the mid 500 ft.lbs. range. Close examination of the primers and comparing them to the Blazer 357 Magnum and some 38 special loads I shot today showed absolutely no indication of excess pressure. In fact the primers looked identical to those in the Blazer ammo and that Blazer is only loaded to 1150 fps. Case staining on the sides of the cases also matched the Blazer and that's a further indication that the operating pressure was somewhat low. If it weren't for the excessive muzzle flash and blast I would say it's an excellent load. However with all that flash and blast I'm going to look for something a bit faster for these bullets.

You are within a few tenths of max with those H110 loads.
Your velocity is probably pushing 1550 to 1600fps. Hodgdon says 1800 or so! Faster is going to be hard to do.

__________________
USAF, 69-92
Vietnam, 72-73

If you are looking for alternatives with 125 jhp, Speer's data with VV N110, if ya got any. AA-7 (mag primer) for very accurate mid range 1300 fps.

Thanks for the tip Zeke, Accurate #7 is actually available at the Fin down in Ohio, might have to pick some up. How is the muzzle flash with the #7?

I'm also considering trying out Accurate #5. Lyman lists it for a 125 grain bullet in 357 Magnum to the mid 1300's and my previous experience with it in some 1050 fps 185 gn. 45 ACP loads has shown it to be a low flash powder when loaded fairly hot. Kind of hate to break into my stash of #5 because I only have 2 lbs. left but realistically it shouldn't hurt too much to load up 30 rounds for some testing.

AA-7 does not have the "boom" of the slower powders, and no where near the muzzle flash.

Have never tried AA-5 in 357, and am not familiar with what it works good with.

IIRC,H110 is same-same as WW296. If you read the WW load data, it states to use 296 data as printed, not to reduce the charge and work up.

BTW, published load data is, as someone else noted, particular to those load components in that particular barrel on that day. Two virtually identical barrels chambered on the same machine, same reamer by the same machinist will produce different results.