Strange 357 Mag results

[wrangler5]

I decided to work up a 357 Magnum load for my Ruger Blackhawk using Remington 158g JHP bullets and Accurate #9 powder. I made up 10 different sets stepping up in 0.2g increments from the 13.5g starting load to the 15.0g max load shown in the Accurate Data Book for Hornady 158g XTP bullets - the only 158g jacketed bullet they list. (I made 14.8g and 15.0g loads, to approach the maximum slowly.)

The starting load averaged 1435 fps, almost exactly what Accurate reported for their equivalent XTP load. But the rest were all over the lot. Going UP in powder load, the average velocities were 1405, 1385, 1372, 1354, 1367, 1394, 1397, 1389, and 1425 fps for the 15.0g load.

I'm pretty methodical when I make up these test loads. All cases are sized, primed and expanded first and put in loading blocks. The powder measure (Redding 3BR) is adjusted so that 10 loads in a pan are +/- 0.3g of 10x the desired single load (i.e., for the starting load, 10 throws of the powder measure weighed between 134.7g and 135.3g.) Then 10 cases are charged at that powder measure setting, the bullets seated and crimped, and the loads put in one row of a marked ammo box. Then on to the next level. All bullets are seated and crimped without adjusting the dies (I use a progressive press for all this work.)

The primers on the 15.0g load were considerably flatter than on the 13.5g load so pressures were going up, but the velocities certainly didn't show it. Any guesses as to what might be going on here?

 

[DJW]

yes, what is going on is that your results tell you that 13.5 gr. is the charge that yields the highest velocity. if you read the Lee loading manual you will see that he states his opinion that a starting load has many advantages, among them is the lessened wear and tear on both gun and shooter. in this case higher velocity is just a bonus. don't always assume you will get higher velocity with higher charges.

 

[HSMITH]

Try a search on 'WESHOOT2' as the username and 'work up' as the search term. He has posted very good information on what you saw in your workups.

You basically hit all that powder is going to do with the start load, adding powder only increases peak pressure. When you START to see this trend in the future STOP RIGHT THERE. Some powders are not nearly as forgiving and will spike extremely high pressures with small increase in charge weight.

Had you done this same thing with Blue Dot you would have gone from the top velocity load, to slightly sticky cases with .2 increase, to HARD stuck cases with the next .2, and possibly a bulged cylinder with another .2.

 

[CB900F]

Wrangler;

Your results are an excellent example of why it pays to have more than one reloading manual also.

Let's take a look at Hornady 6th edition, since they make the bullet you're using. The test gun is a Colt Python with an 8 inch barrel. A major factor,that you did not reveal in your information, is the length of the barrel of your Ruger Blackhawk.

The starting load in the Hornady manual for AA #9 powder is 9.7 grains with any of the three bullets listed as 158 gr XTP. Which one of the three did you use? That starting load gives a velocity of 1000 fps in their test gun.

They then list four additional loads of 10.1, 10.6, 11.0, and 11.5 grains of AA #9. Note that the increments are not consistant, however the velocity steps are: 1050 fps, 1100 fps, 1150 fps, and 1200 fps.

Now I'll grant that the Ruger is generally considered to be a stronger gun than the Colt, but let's get real here about the charges you're using. That's pretty damn hot. What was the test gun in the Accurate book?

For comparison, take a look at what Speer #13 has to say about using their 158 grain bullets with AA #9, S&W model 19 6" barrel test gun. Start load is 12.3 grains & max load is 13.7 grains, with a velocity spread of 1052 fps to 1136 fps. And AA #9 is the eighth powder down on Speer's list.

It would seem to me that a very possible reason for your inconsistant results is that you are pushing considerable amounts of unburned powder out the barrel. Particularly if you have a short barreled Blackhawk.

I've always found it advisable to use the bullet makers manuals over the powder makers info. One has a vested interest in pushing powder sales, the other doesn't.

900F

 

[wrangler5]

Thanks for the replies. The barrel of my Blackhawk is 6.5 inches, and the Accurate data book used an 8 inch test barrel. Accurate indicated that the top load in their book (15.0g) was just below the SAAMI max pressure. But I should have been alerted to a potential problem when cases didn't just fall out of the cylinder as they usually do with my mild loads. Only the top load took some real pressure on the ejector rod to get the cases out, but most of the loads did take at least a poke. I didn't associate this with "sticking cases" but in retrospect I probably should have.

900F, I appreciate your reminding me of the other manuals. I have the Speer #13 but just didn't look at it. The Speer JHP is probably closer in construction to the Remington bullets that I was actually loading than the XTP. I'll just dial things back down to the 13.5g level in the future when I want a full magnum load. Looking back in my records I see that my experiments with AA#7 resulted in a similar "wobbling" of the velocities as I approached the top load in the Accurate book.

 

[MNgoldenbear]

I'd disagree that velocities wouldn't be going up with higher pressure, though velocity isn't everything. If you are getting consistent, accurate loads with the starting load and poor results with higher loads, go with the starting load. Since the cases were sticking, your pressures were obviously high, and it's best to back down from those loads anyway.

I agree with 900F's statement that the variance in velocity of the heavier charges may be a result of varying amounts of the (excess) powder charge actually being burned. This would also result in only some of the rounds exhibiting excessive pressure, while others might seem "normal". Not good for accuracy or safety.

I had a similar experience when I started reloading. Starting load in the Sierra manual worked just fine. What should have been "moderate" loads caused sticky extraction, to the point of having to tap the cases out of the cylinder with a cleaning rod. (Okay, so I was a REAL newbie at that point and not especially bright, and was pretty much learning the ropes on my own. Lucky to still have the gun and my fingers!)

Would wonder though about some other stuff. What chrono? Lighting conditions/sources? Velocity variance within strings/between trials of same load? None of these really matter, just points of curiosity reagarding the source of variability. In the end, sounds like you've now developed and settled on a safe and effective load -- mission accomplished! Shoot well!

 

[Clark]

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

From my load notes:

Load Book:
Accurate Arms max load for AA#9, 158 gr.
357 mag, 1994-2000, 13 gr.
357 mag, 2001, 15 gr.

My results;
Colt Police Positive 38 special, I got the revolver police surplus made in the 50's
16.7 gr., ok
17 gr., cases stick

In this 1993 post, John Bercovitz [JPL ME and my collaborator on bulk cz52 barrel buy] explains why sticky cases happen with lower loads in revolvers with thinner chamber walls:
http://groups.google.com/group/rec....ovitz+brass+357&rnum=1&hl=en#921215b9dcac6d5c

 

[CB900F]

Clark;

Sorry, I don't understand the rational between: "explains why sticky cases happen with lower loads in revolvers with thinner chamber walls" and Wrangler's Ruger Blackhawk. The Blackhawk is usually thought of as having hell-for-stout chamber walls & overall construction.

900F

 

[wrangler5]

Even though my Blackhawk is a 3-screw, and so has the "medium" size cylinder (not the 44 Mag size that I understand the 357 "New Model" had until the recent return to the flattop design and size of old) I'd still say my cylinder walls are hell for stout.

BTW, all the remaining rounds from my experiment have been pulled, and I'm in the process of making up a box of "full magnum" 357 loads using the Sierra manual and some tests I made last month with the same bullet using AA#7.

Thanks again for all the good and prompt feedback.

 

[Clark]

OK will try harder,

Wrangler5 put AA#9 [slow pistol ball powder] in his 357 mag revolver and 158 gr. bullets and the pressure goes up with change, but not the velocities.

I have put LIL'GUN [slow pistol ball powder] in my converted 357 mag revolver and 158 gr. bullets and the pressure goes up with change, but not the velocities.


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

A) Colt Police Positive 38 Special 4" barrel:
1) cheap reloads mixed brand brass 158 gr. JHP, 830 fps
2) 18 gr. LIL'GUN 158 gr. XTP 1.59", WSPM, 1173 fps
3) 23.5 gr. LIL'GUN 158 gr. XTP 1.59", WSPM, 1155 fps

It kicks harder, makes more noise, but the chrono does not go up.

From my experiments and John B's math, wrangler5 is a long way from the real pressure limit.

What do I think?
1) The AA#9 powder is too slow and is blowing out the muzzle un burned
a) use a heavier crimp
b) magnum primer
c) back off on charge
d) go to a faster powder.