.357 magnum load data

[Rule3]

Thank you everyone for all the quick replies and great advise. I decided to start off at 17 gn of the H110 for a starting load. Gonna head to the range after work today and try out the 20 I have made up already. I'll post the results after these test rounds have been fired.

This thread scares me. New reloader, progressive press, 2" barrel loading H110/296 with 125gr bullet, Guessing at powder charge below start load (which is not good for H110 powder!

H110/296 will create a lot of blast and flash in a short barrel

Use the data given by Hodgdon as Walkalong suggested,

 

[35 Whelen]

Thank you everyone for all the quick replies and great advise. I decided to start off at 17 gn of the H110 for a starting load. Gonna head to the range after work today and try out the 20 I have made up already. I'll post the results after these test rounds have been fired.

If you're using H110 in a 2" .357, don't forget your tinted face shield, asbestos gloves, FR clothing and a fire extinguisher when you go to shoot.

35W

 

[Down Range Dan]

Just got back from the range after testing my the first set of 20 rounds. In this test all rounds fired with no squids. There was a muzzle flash but nothing more than factory loads. Grouping was actually pretty decent, this pic is from 5 yards out. I will say that H110 is some dirty powder. I did a comparison with my loads versus a few factory loads and mine seem to be a touch under powered so I think I will make a few more rounds at 18 gn and maybe up to 19 gn if needed. Is making a full 1 gn adjustment too much all at once?

 

[DMW1116]

My policy for rifle bullets has been for a while that Hornady bullets get Hornady data. I've had disturbing results when using generic data for Hornady bullets. I am not normally that cautious for Hornady pistol bullets, but for this case, I'd probably use my standard policy and say Hornady bullets get Hornady data.

 

[AJC1]

Just got back from the range after testing my the first set of 20 rounds. In this test all rounds fired with no squids. There was a muzzle flash but nothing more than factory loads. Grouping was actually pretty decent, this pic is from 5 yards out. I will say that H110 is some dirty powder. I did a comparison with my loads versit will us a few factory loads and mine seem to be a touch under powered so I think I will make a few more rounds at 18 gn and maybe up to 19 gn if needed. Is making a full 1 gn adjustment too much all at once? View attachment 1189566View attachment 1189566

It will clean up as you go higher.... if you shot the 17 grain rounds there were probably chunks. I'd expect 20 grains to burn fairly clean, and take the hair off your hands....

 

[P Flados]

For what it is worth, Quickload says that you reach SAAMI max pressure (35,000 psi) at 20.1 gr of H110/296 under a the 125 loaded to 1.590".

It is also stating that the 20.1g is 103.7% fill (i.e. slightly compressed).

At 22 gr, fill is over 113%. This is way too compressed for a ball powder in my experience. I am suspicious of the Hodgdon data. The only way I could see them loading this much is if they were using cases with more than typical internal capacity.

 

[fxvr5]

At 22 gr, fill is over 113%. This is way too compressed for a ball powder in my experience. I am suspicious of the Hodgdon data. The only way I could see them loading this much is if they were using cases with more than typical internal capacity.

This is starting to reach the realm of conspiracy theory crap. Lyman (50th) has the same data as Hodgdon, with 22.0 gr being the max load of H110 and a 125 gr XTP at 1.590" producing a pressure of 42,600 CUP. They used Federal cases and CCI 550 primers. They note that 22.0 gr is compressed.

 

[Howland937]

making a full 1 gn adjustment too much all at once?

Not if you're still within published data. If your loads feel noticeably underpowered compared to factory and you're getting really dirty brass, you could bump on up a full grain if you're still going to be under max load. Usually I go half grain at a time on anything over a 10 grain. Anything under 10 grain charge weight is done in .2 or .3 increments.. A few guys I've talked to increase charge by percentage (ie. 5 or 10% increments) until they get to where they wanna be.

 

[GeoDudeFlorida]

Just got back from the range after testing my the first set of 20 rounds. In this test all rounds fired with no squids. There was a muzzle flash but nothing more than factory loads. Grouping was actually pretty decent, this pic is from 5 yards out. I will say that H110 is some dirty powder. I did a comparison with my loads versus a few factory loads and mine seem to be a touch under powered so I think I will make a few more rounds at 18 gn and maybe up to 19 gn if needed. Is making a full 1 gn adjustment too much all at once? View attachment 1189566View attachment 1189566

Going up to 18 should be fine. The jump to 19 is a little steep. There’s probably a good load between 17.5 and 18.5. Maybe even 17.5 or 18.5.

 

[AJC1]

Shoot the 20.0 you have loaded. If it's to much h110 is not your jam... it's not mine so set it aside and go with a faster powder....

 

[Rule3]

Just got back from the range after testing my the first set of 20 rounds. In this test all rounds fired with no squids. There was a muzzle flash but nothing more than factory loads. Grouping was actually pretty decent, this pic is from 5 yards out. I will say that H110 is some dirty powder. I did a comparison with my loads versus a few factory loads and mine seem to be a touch under powered so I think I will make a few more rounds at 18 gn and maybe up to 19 gn if needed. Is making a full 1 gn adjustment too much all at once? View attachment 1189566View attachment 1189566

Why do you continue to go against the load data that Hodgdon has?. The start load is 21 grs H110?
H110/W296 is a powder with very little room between min and max loads. Also the reason you claim it was "dirty"

Shooting full house mag loads with a "light bullet" 125 is going to eventually cause damage to the forcing cone and cause flame cutting.
You can get better performance and use less powder by getting some other faster powers. Heck even 2400 uses less and you can vary the load some
Try Longshot, Unique, Power Pistol , HP 38 etc

You can only get so much velocity out of a 2" barrel

 

[fxvr5]

This is starting to reach the realm of conspiracy theory crap. Lyman (50th) has the same data as Hodgdon, with 22.0 gr being the max load of H110 and a 125 gr XTP at 1.590" producing a pressure of 42,600 CUP. They used Federal cases and CCI 550 primers. They note that 22.0 gr is compressed.

Checking my notes, I found that I've shot this load in the past. I have no notes on whether the cases were sticky or not sticky so I can't comment on that. Velocity was a little over 1600 fps from a Ruger Blackhawk with a 6.5" barrel. But, work up to this!

 

[BRatigan]

I found that Gordon's Reloading Tool helps me figure out pressures and various thresholds all based on your inputted data. It's very close with collected data from my Chronograph. It may or it may not help you. It is free of charge. https://grtools.de/doku.php. Bullet, powder and cartridge data is already in the tool so you can get info relatively quickly once you get up to speed with the program. It tells you when you have exceeded pressure thresholds which I find very useful.

 

[Mr_Flintstone]

I ran a simulation this morning on GRT using Hornady handgun load data from Hornady X. Below are the results in graph form.

Using GRT defaults, it showed that 19.9 gr H110 was ever so slightly above SAAMI max. I included the cylinder measure and added a cylinder gap for a revolver with a 2” barrel. According to the ladder steps, 17.4 gr H110 should be about 22,000 psi and give about 900 fps from a 2” barrel.

 

[fxvr5]

Using GRT defaults, it showed that 19.9 gr H110 was ever so slightly above SAAMI max. I included the cylinder measure and added a cylinder gap for a revolver with a 2” barrel. According to the ladder steps, 17.4 gr H110 should be about 22,000 psi and give about 900 fps from a 2” barrel.

My notes show the Hornady 125 XTP bullet has a length of 0.545". What does GRT predict with that bullet length? Thanks.

 

[Mr_Flintstone]

My notes show the Hornady 125 XTP bullet has a length of 0.545". What does GRT predict with that bullet length? Thanks.

They are indeed 0.545”. I made that change in Gordon’s, and the results are below.


It did change the pressures slightly, but still shows 20.0 grains to be a max charge.

 

[Mr_Flintstone]

I think the main issue here is the whole CUP/PSI measurement differences. Hodgdon uses CUP measures while Hornady uses PSI. I’m sure that Hodgdon tested their loads accurately and consistently using the copper crusher method that was consistent with what was used when .357 magnum was developed. If their tests show less than 45,000 CUP, and SAAMI says 45,000 CUP is safe, who am I to dispute that statement. Hornady, I have no doubt, applied a similarly consistent testing procedure with the piezoelectric transducer method, and got very different load ranges with H110 powder.

Now here’s the rub. How can 21.5 grains of H110 be safe when measured with a copper crusher, and not safe when measured with a transducer? Obviously it can’t be both.

 

[fxvr5]

Now here’s the rub. How can 21.5 grains of H110 be safe when measured with a copper crusher, and not safe when measured with a transducer? Obviously it can’t be both.

The difference could simply be powder lot number, primer, and case capacity. These could account for the difference independent of measuring method. The only way to know it is to use both methods on the same batch of ammo.

 

[P Flados]

I have run into a few examples where a compressed load with a ball powder in a straight wall case resulted in Quickload (QL) result significantly over measured pressures.

However, further investigation says that this example is mostly a "bad inputs" issue.

I checked a Federal 357 case and found it took 27.4 gr of H110 to fill the case. I then plugged in 27.4 gr H110 into QL and set the OAL for zero seating depth. Quickload said that this was a 108.2% fill instead of the measured 100% fill.

I then did the water capacity test and found the Fed case to hold 27.0 gr of water. The QL default was 25.5 gr.

I changed the QL water capacity to 27 gr and the fill percentage went to 102.6%.

This means that the case capacity and the powder density were both off, and the combined error was significant. With cases capacity tweaked to 27.7 gr of water, the percent fill is effectively fixed (27.4 gr of H110 gives 100% fill at 0 seating depth).

With the above "fudged" input, the max allowed SAAMI pressure of 35,000 psi is reached at 99.9% fill with 21.4 gr of H110. This is much closer to the Hodgdon data. Lot to lot variations for powder batches and variations in case capacities can easily explain this magnitude of difference in results.

As far as running a compressed load of lets say 104% of H110, I would not expect to see an "signs of pressure" in any stout gun. The resultant pressure is likely to be close to 45000 psi. I load a lot of different cartridges with essentially the same case diameter in my TC Contender. If you fire a 55,000 psi 357 mag load in a Contender, what "sign of pressure" would you expect. Primer appearance will vary from brand to brand, but some amount of "flat primer" will show up at anything over 30,000 psi and perforations are not expected until probably over 65,000 psi. Sticky extraction is not expected until probably over 60,000 psi.

Given the above, I would recommend avoiding any compressed loads of H110 under a 125 gr or bigger bullet unless both there is a real need and the ammo is only going to be used in a "stout" gun. Using a percent fill as a "double check" for a max charge really helps deal with making sure that everything "matches up" with expectations.

 

[Mr_Flintstone]

The difference could simply be powder lot number, primer, and case capacity. These could account for the difference independent of measuring method. The only way to know it is to use both methods on the same batch of ammo.

It very well could be, but that’s a lot of variation. It would be interesting to know how the 35,000 psi was settled upon. 357 magnum was developed and originally tested using CUP, and I’m going to bet that not every powder that was tested at 45,000 CUP was exactly 35,000 PSI when tested with a transducer. It makes sense to me that some could test over and others under, and the 35,000 PSI was taken as an average value.

Then there’s the whole rumor about SAAMI setting an intentionally low PSI value (some say 10-20% lower) because some of the K-Frame Smith and Wesson revolvers were not rated for full time 357 Magnum use. I don’t know the truth of this and will not speculate on it. I only mention it because for whatever reason, some loads that approach 35,000 psi do seem to be about 10% (give or take) lower than what is listed as a 45,000 CUP max.

It would simpler if everything was standardized like CIP data, where you don’t have two competing pressure models.

 

[fxvr5]

There was a recent article in Shooting Times that showed the ballistics of the 357 Magnum has not changed since it's introduction in 1935. In fact, the data showed it has increased speed a little since then (a 158 lead bullet at 1518 fps in 1935 (in an article by Elmer Keith), compared to a 158 at 1550 fps in 1963 with the introduction of jacketed bullets - all in 8 3/4" and 8 3/8" barrels). Now, this does not address the pressure standards per se, but it suggests no major changes.

 

[Mostly Lead]

Now, with the load data being different between the two manufacturers which one do I pay attention to the most. Powder data or bullet data? Also, do these load data amounts seem too high?

And with the drastic difference in barrel lengths between what the load data says and what I'm shooting, how do I compensate for that?

1) That is your choice to make. Lots of good advice already give to help with that.
2) They seem consistent with other published data.
3) You don't. Informational only, but you might not see the same performance in a shorter barrel.

H-110 in the Lyman 49th and Lee's Modern Reloading 2nd edition are consistent. I also have Speer 13 to compare with and it is a bit different but doesn't list the XTP specifically, just a JHP. Between those three and the manufacturers websites, I'm able to come up with loads that are satisfactory "for me and my guns only".

Reloading still offers you the opportunity to take personal responsibility for your health & safety. Seems like you're taking that seriously, so - kudos.

 

[fxvr5]

You have no other information on these load manuals? Is the different data for small and large framed revolvers for the 357 Magnum, or for the 38 Special? Anything?

Any information at all on the pressures they loaded to? Anything?

Never mind. I found a manual with that information.

 

[AJC1]

Never mind. I found a manual with that information.

The old Lyman manuals also have it if your looking for more... they are labeled for large framed revolvers.

 

[fxvr5]

I found the 1955 Lyman Ideal manual # 40. They have two sets of 357 Magnum data. One they list as Moderate Loads which they say is loaded to "22,000 to 23,000 lb. class". Their High Power Loads are loaded to "above 25,000 lb. and for use in large framed revolvers in good condition only".

There's no mention in the copy I found that explains how they were measuring the pressure or what limit they had, if any. But the PDF starts on page 42, so who knows what was left out.

In the Lyman Ideal handbook # 38, 1951, they explain the use of a copper crusher to measure pressure, so it's likely they used that method in subsequent manuals. They list data for one 156 grain lead 357 bullet only, and note: "these are all 20,000 lb. pressure loads and are considered safe in heavy frame guns in good condition." Their load with Unique is 6.0 grains, and this is the same load they list for Moderate Loads in their 1955 manual. Their High Power load in the 1955 manual shows a charge max of 8.5 grains of Unique with this same bullet. Quite a difference.

Edited to add: I did not see any mention of a pressure limits for the 357, but I might have missed it.

Where I found the manuals: https://www.24hourcampfire.com/ubbt...-collection-of-reloading-data-old-and-current