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Discussion Starter #1
I'm just getting started with reloading but am a little confused on differences in load data. For example, I'm looking at the following .38 sp load:

Bullet: Hornady 125 gr. FP XTP
Powder: W231
Primer: WSP

Hornady’s 9th edition lists the starting load at 4.8 gr /max load 5.7 gr. However, the Hodgdon website shows a starting load 4.3 gr/max load 4.9 gr. for the same bullet.

Why the difference? The manual says published loads are within safe pressure limits, but why is the Hornady range so much higher than Hodgdon? If I start at 4.8 gr. and work up, I'm almost beyond the max range that Hodgdon recommends. What am I missing?
Thanks for any help!
 

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You didn't say, but are they both for W231 powder?

Were they both using the same test gun? One might be a pressure barrel, the other a Ruger or S&W. That would make a difference too.

I would read the fine print. I doubt that the test setup would be exactly the same in both cases.
 

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As stated, each loading manual shows the results of their testing using their particular gun and their brands and lots of components.
The rule is to use the lowest starting load you can find. That implies a minimum of two sources. In most cases, the starting load is simply a 10% reduction from the max load and is not the minimum safe load.
In 40 years, I have twice found the starting load in a manual to be max or over max in my gun and my components. This does not mean the manual was wrong, it means that I am lucky I did not simply start off with that starting load. In several other guns, that starting load was perfectly fine, but in the one gun, it had recoil harder than factory and the cases were thrown far from my main pile.
Also, if you ever see a starting load that is less than a 10% reduction, consider that powder to be a poor choice as it almost certainly shows that the test facility found pressure spikes up to or above the max before the load produced anticipated velocity.
This is often found with N310 and Clays powder.
I have found that both of these powders, and TiteGroup in my guns, to show sudden pressure spikes as I worked up to max load. I stopped using those powders in both .38 Spl and .45 Auto based on these results.
Others have not had this problem, but it does happen.
Always inspect your cases, how far they were ejected, and how the recoil felt and compare back to factory--particularly if you are trying to work up a max load for max performance.
 

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Nothing says a reloading manual's Max loads have to be SAAMI max pressure. I've found Hornady loads are quite conservative compared to Speer. Hodgdon's loads are seldom close to SAAMI max.
 

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Bullet design can make a difference, also look for min. OAL, bullets seated deeper develop more pressure as they have less case capacity and require less powder charge. If your OAL is more than the minimum in the manual you are using approaching max. loads is not as much of an issue, but if you are seating bullet to less than Min. OAL pressure can shoot up fast. I usually try to stay at least 5% or more below max. loads, if for some reason i should ever need a 100% max. load i would rather use a more powerful handgun.
 

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Chamber specs, barrels, brass, primers, CUP Vs. PSI, and powder lot variations. Remember that everything has a spec'd RANGE.
1967 WC846 in the 5.56 NATO had up to 1% Calcium Carbonate, gas tubes didn't like that. Cut the spec'd max to .25% and re-label to WC844. Keep WC846 name for the 7.62.
Remember that non-canister grade powders get blended to even tighter specs to be sold to the reloading public(canister grade).
844 & 846 are the same powder, aside from a small amount of stabilizer.
You know 846 as BLC-2
844 you call H335, or Win 748.
 

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Discussion Starter #9
You didn't say, but are they both for W231 powder?

Were they both using the same test gun? One might be a pressure barrel, the other a Ruger or S&W. That would make a difference too.

I would read the fine print. I doubt that the test setup would be exactly the same in both cases.
Yes, both were for w231 powder.
 

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Discussion Starter #10
Nothing says a reloading manual's Max loads have to be SAAMI max pressure. I've found Hornady loads are quite conservative compared to Speer. Hodgdon's loads are seldom close to SAAMI max.
Thanks. Hornady indicates which loads are +p, can I assume that their loads below that are within SAAMI specs?
 

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Discussion Starter #11
Bullet design can make a difference, also look for min. OAL, bullets seated deeper develop more pressure as they have less case capacity and require less powder charge. If your OAL is more than the minimum in the manual you are using approaching max. loads is not as much of an issue, but if you are seating bullet to less than Min. OAL pressure can shoot up fast. I usually try to stay at least 5% or more below max. loads, if for some reason i should ever need a 100% max. load i would rather use a more powerful handgun.
CJS1945, I plan to keep my loads at or above the OAL indicated, which in this case is 1.450"
 

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Gringo,
CALL your two sources for load data, they both have 800 numbers. Ask WHEN the data was shot. OR pick the lower of the two and load some test rounds.

RELATIVELY speaking low end loads give up little velocity, for a large reduction in pressure. Ergo: MAX loads gain little other than stress on the system. If YOU want to know what pressures YOUR gun is developing, buy a Pressure Trace.
 

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Different barrel, different atmospheric conditions, different lawyers etc can all lead to vastly different data.
 

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For reference, I have loaded those bullets (125gr XTP) with 5.5gr of W231 with a OAL of 1.450" and was very happy with the results with no signs of high pressure.

I've also made them with 4.7gr but the accuracy was better for me with the 5.5 out of my 4" GP100.

I don't have a chrono so can't speak to the speeds.

As always, please don't use my loads without consulting various reloading manuals.
 

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Gringo, Just some FYI about reloading manuals ... The three most popular manuals .... Speer, Hornady, and Sierra all have their own SAAMI approved testing labs. Every load listed in their manuals has been tested and is within SAAMI's established pressure standards for each cartridge. All the above companies make bullets so they only test their listed loads with their own bullets. This fact alone is why different manuals may show different charge weights for the same bullet weight. Different brands of bullets in the same weight will have slightly different profiles, different bullet-to-bore bearing surface, and different seating depths. Even bullet diameters may be different. One good example is Hornady 44 cal jacketed bullets are .430" whereas other brands are .429". These differences will affect chamber pressure so I would be wary if I saw the exact same load data in different manuals with different bullets.

Further, manuals list their loads in a different format. For example ... Speer gives a starting load and a max load whereas Hornady lists their loads in 50 fps increments. When the Hornady manual indicates a max load, it means the load is within SAAMI pressure limits, however the next highest 50 fps load increment may exceed limits. Reputable reloading manuals have to consider "worst case scenarios". Maybe the powder drop was not perfect, maybe the loads were fired on a hot day, maybe the bullets were not seated to exact specs, etc. As such, these manuals always stay well under SAAMI max pressure standards to provide a margin of safety.

Lee, Lyman, and powder companies DO NOT have their own SAAMI labs for pressure testing loads so they "borrow" data from other sources. Some of these loads are "generic" and do not specify an exact brand/style of bullet. I consider these sources much like other Internet sources ... NOT RELIABLE. All modern SAAMI labs now use piezo transducers to test chamber pressure in a lab using a special test barrel. These pressures are measured in psi, versus the old crusher method, which are rated in CUP. When ever you see load data rated in CUP, it is old data ... not nearly as accurate as new data rated in psi.

Good reloading manuals always indicate the brand, model, and barrel length of the gun actually used for chronograph testing (velocity) so one manual may use a revolver with a 4" barrel and another may use a 6" barrel. That's one of the prime reasons why stated velocities may be different.

Last but not least .... no where does it say a specific load has to test at SAAMI max pressure to be considered a "max load" by the company that wrote the manual. Each company has their own policy on how close to SAAMI max pressure they want to get and none of them want to get sued so they tend to be quite conservative.
 

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Discussion Starter #18
Iowegan, thanks for the explanation and thanks to the others who responded. I called Hodgdon and was told the same as others have said, everything depends on the components and test conditions. They also said that changing brass can lead to different results, and its a good practice to sort loads by brass to check for consistency (I thought that was good advice for a new reloader). Bottom line was that they said to start with their starting loads or the starting load from a manual and work up from there.
 
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