The chronograph and .357 Magnum load questions.

[Kelly Green]

I’ve been a handloader for decades but I’m new to the chronograph. In the past I would go by the feel of the recoil and examination of the spent brass when testing loads. Life was simple in the old days. Maybe not smart but simple.

I bought a chronograph and now I have questions about the .357 Magnum loads described below.

Load 1
Magtech Factory Load
Bullet…158gr. SJSP
Average Velocity…1065

Load 2
Bullet…Nosler 158 gr. JHP
Powder…8.6 gr. AA#5
Brass…CBC
Primer…CCI 500
Average Velocity…814

Load 3
Bullet…Nosler 158 gr. JHP
Powder…9.1 gr. AA#5
Brass…CBC
Primer…CCI 500
Average Velocity…917

Nosler data shows the velocity for Load 2 and Load 3 as being:
8.6 gr. AA#5 and Nosler 158gr. JHP: Velocity…1258
9.1 gr. AA#5 and Nosler 158gr. JHP: Velocity…1343

I fired 6 rounds of each from a very clean S&W Model 19 with a 2.5” barrel to obtain an average. Each round was seated to identical depth on the canular with a tight crimp. The primers were seated slightly below flush and tight. The Velocity deviation in each group of six was fairly consistent. I checked the bullets and they weigh 158gr.

The velocity of my loads are pretty far off published data. The factory load should also be faster than what I got, in my opinion. Even the Lee manual states that a 9.0gr. load of AA#5 is capable of propelling a 158gr. lead bullet at a velocity of 1354.

I know that different guns, even with identical barrel lengths, will exhibit different velocities with the same bullet and that the manual data is usually compiled from longer barreled pistols and revolvers.

I checked the chronograph by shooting a 1911 and a S&W Model 10 with hand loads and the results were close to published data. Unfortunately I don’t have another .357 to test against.

For the .357 I can go to up to the max charge of 9.6gr. of AA#5 or change to a faster powder or a slower powder. If I load for a velocity of 1200 to 1300 the pressure may be too great. Any suggestions?

Thanks in advance,
Kel

 

[tappedandtagged]

Load some AA #9. It will get you up there. I load 12 grains over a cast 158 swc. I don't recall the fps, but it was close to factory.

 

[Nick B]

Nosler used a 8.3" barrel in their testing . You're using a 2.5" .
Big difference when it comes to velocity .

 

[arizona98tj]

I've no doubt you are correct in regards to the test barrels used in the reloading manual being more than 2.5" long. That being said, velocity is but one indicator to use in working up a load, in my opinion. It doesn't replace any of the previous techniques you were using.

Just because a load in the book went to 1200 FPS, that doesn't mean you can keep increasing your powder charge until achieving it. Doing so would be dangerous to say the least. There is no fix for having a short barrel short of replacing it with a longer one.

 

[Iggy]

A rule of thumb is that you lose 50 fps per second with every inch of barrel reduction.

 

[MDMarauder]

Nosler data uses a longer barrel, longer = faster FPS
Look for barrel length used for the data tests.

 

[125JHP]

I have tested 9.0gr (of AA-5) under a 158 Berrys plated bullet and from my 4" M-19 it does 1013 and from my 6" M-686 its up to 1080. These don't have crimp ring so I taper cripm them at an OAL of 1.55" and used CBC nickle brass.

At 2" shorter and 100fps slower, your load looks like it is right on track.

As a side note, I've also noticed 50fps difference between different guns, same model, same barrel length, same load.

 

[alwslate]

I have loaded a fair amount of 357 mag ammo, mostly for 4" and 6"
revolvers. The velocities listed in loading manuals for jacketed bullets
that are obtained in their test barrels are almost completely irrelevant
for the handloader using a revolver. Also the revolver user will usually
find it much easier to obtain " magnum " velocities with cast bullets
rather than jacketed bullets. For some reason this velocity discrepancy
between cast and jacketed handloads seems much lower in the 44 Mag
than in the 357 Mag and is one reason I rarely use jacketed bullets
in 357 handloads.

 

[jaymoore]

A bit OT, but that velocity loss is why I like the 9mm in a snubbie revolver. My Model 940 usually puts out better numbers than the .357 snubbies chronographed.

So, nothing wrong with your data! Just hard to get that big case to work efficently in such a small package.

 

[Erich]

Chrono is eye-opening, isn't it?

You're going to have difficulty reaching 1200-1300 fps with a 2.5" tube and a 158-gr jacketed bullet. Moving to a quality hardcast (I recommend Tennessee Valley Bullets - their lube gets me better velocities than other hardcasts deliver) will help a bit, but the main thing that you need to do it change powders (think Lil' Gun, 2400, H-110) and maybe set your goals a little lower.

FWIW, at this altitude (and that helps), I can get into the mid-1300-fps range with my 3" SP-101 with 158-gr TVB hardcasts and max loads of 2400 or Lil' Gun.

 

[Nevada Ed]

Nothing like a chrony to open up the "Real world" of velositys to a reloader.
They had it right in the old days..........." White man speak with forked tounge" !!

Some of the data was from a 11" non-vented barrel and as stated some from a 8.5" barrel. Later the industry tried to settle on a 6" vented barrel to try to get the data closer for velosity purposes.

If you can get your copper jackets into the 900 fps you should be getting some expansion,depending on how hard the copper is and brand of bullets you are using.
Lighter jacket bullets will mushroom easier at the higher velositys but you will get more penetration with the heavier bullets. Just depends on what you are looking for. Can't beat the slow lead wc bullets for target work.
You will find that the snub nose is a lot harder to get a good load out of than the longer barrels like 4" or longer since the powders have less barrel to stabilize the velositys and you might find that a med to hvy crimp is needed for your chrony to start to get a steady reading on powders used.
My 38 snub did not do well with most fast and slow powders for maximum loads and the medium powder worked out best for +P loads but that was my revolver, yours may like the other powders.
Good luck finding a good load.

 

[Rule3]

All good info above. Not only the test was in a much longer barrel but commercial loads have powder that we don't.

The best you can do as mentioned is H100 or 2400. I like Power Pistol and can get some Zip out that.