357 mag, I'm confused

[c1skout]

I was looking through my load notes binder this afternoon and noticed something weird. The 3 loads I tested one day were a 158swc over Bullseye powder, CCI550 primer. My first was 5.9gr and made 1103fps (average), second load 6.1gr and showed 1271fps, third load 6.3gr but only 1148fps! Did I mis-label my loads before shooting or maybe transpose the info incorrectly, or will this combo do strange things with pressure or velocity?

[Scharfschuetze]

Hard to say from my end, but the good thing about good testing technique is that your results should be repeatable on demand. I'd retest the sequence of your loads to see if you get the same results or if not, to confirm a mix up in the recording of the data during the original test.

Let us know if you do. I'd be interested as common knowledge and experience would argue against the hotter load dropping its velocity by 123 fps from the milder 6.1 grain load. Anything is possible I guess, but I'd wager that the 1271 fps load was actually the 6.3 grain of BE load.

Preferring slower powders in the 357, I've never used BE in my 357 Magnum loads so I'd also be interested in the extreme spread and standard deviation of the loads.

[Tatume]

How many shots did you fire with each load? Any less than five is completely unreliable for a mean muzzle velocity. Ten is better. Also, in my experience, fewer than twenty shots is worthless for a standard deviation on velocity (based on a study I did using prototype Federal 22lr match ammo, conducted in the wind tunnel at NASA/Langley Air Force Base).

I see people making all sorts of claims based on small samples that can have enough random error to totally mask the true results. I know it is expensive in both time and money to increase sample size. On the other hand, paying something for nothing is not cost effective either.

[Hickory]

Bullseye powder, in my opinion, is best suited for light loads.
My past experience with bullseye is that, most anything over 950 fps and everything becomes erratic; velocities, pressure, grouping and barrel leading.

[cbrick]

I'm curious, why the mag primer for small charges of an easy to ignite fast powder? I wonder if this could have caused velocity swings in the chrono numbers via the force of the primer causing boolit jump before powder ignition.

I also believe the BE in a magnum case is best left to light loads with light boolits and if higher velocity is called for so is a slower powder. I'm a big fan of heavy for caliber boolits with as slow a powder as will reach the desired velocity.

Tatume is correct about sample size. If only a few rounds were fired over the chrono the results could very well be faulty.

Rick

[44man]

I'm curious, why the mag primer for small charges of an easy to ignite fast powder? I wonder if this could have caused velocity swings in the chrono numbers via the force of the primer causing boolit jump before powder ignition.

I also believe the BE in a magnum case is best left to light loads with light boolits and if higher velocity is called for so is a slower powder. I'm a big fan of heavy for caliber boolits with as slow a powder as will reach the desired velocity.

Tatume is correct about sample size. If only a few rounds were fired over the chrono the results could very well be faulty.

Rick

My thoughts exactly!

[c1skout]

Ok, here's some more info. I only recorded the vel. spread of the 5.9gr load, 93fps. I shoot 10 shots of each change when I'm testing velocity. The Bullseye powder and mag primers are what I've got. I've got some more of the 6.1gr loaded up (best load for that gun I've found yet) and I'll try some over the chrony next time I have it out, but my notes tell me it was 24deg last test and I might not see those temps for 4 months!
Supplies are still thin on the ground around here, but I'm open to suggestions for slower powders to watch for. I've only got Bullseye, 231, and 296.

[phonejack]

Some time back I chrono'd some Unique loads in a .357 rifle. The 6.0 load was higher than the 6.5 load. I did retest with the same result . Go figure.

[44man]

It is a fact that adding more powder can raise pressures with very little gain in velocity. Velocity CAN go down.
Lot of reasons. Flame propegation through more powder, bullet movement before ignition, primer, weight of powder added to bullet weight, air space, compressed load, burn rate and where pressure peaks.
I have to add alloy, skid, slump, gas escape. Pressure peak at the gap on revolvers.
Loading is to make noise, reloading is to understand and the revolver is the hardest EVER.
I never tried to get velocity with fast powders, not a good idea in any gun.

[Char-Gar]

A couple of thoughts;

1. Study up on the concept of "over bore" i.e. the point where nothing is to be gained by adding more powder. It is a well known and long recognized aspect of small arms ammo.
2. BE wrong powder for even low end magnum loads.

[cbrick]

Ok, here's some more info. I only recorded the vel. spread of the 5.9gr load, 93fps.

I've only got Bullseye, 231, and 296.

You might have guessed from my previous post that I'm not a fan of uber fast powders in a mag case. If you must use BE in the 357 you would be well served to be content with mouse phart loads. To attempt making magnum loads with the BE could be an exercise in futility if accuracy (spelled consistency) is of any concern.

Here are chrono results from my 357 revolver using H-110 & RCBS 180 gr. silhouette boolit.

E.S. 26
A.V. 1536
S.D. 8

Try your 296 in the mag case, it's a fine mag revolver powder but doesn't work well reduced. It needs good bullet pull, decent crimp & boolit weight to burn well (spelled consistently).

Hope this helps,

Rick

[MtGun44]

Try around 15-16 gr of 296, and lose the mag primers for BE for light loads.

Bill

[c1skout]

Well I took an hour trip yesterday to a gunshop and found a pound of 2400. Turns out my 296 supply is low enough that I wouldn't want to start looking for a load with that. I do have small pistol primers but I've been using them in my 38 super, 380, and 38spl. Would I be better off with the mag primers for the super? (I'm gonna burn them up somewhere)
cbrick that's an impressive load! I had debated with myself about 180 or 158 mold to start with but decided the 158 should do everything I need. I've been trying to save money by buying whatever I thought would be the most versatile to use, and while that has worked for years for my auto guns, I'm learning now that I'm money ahead not trying that with revolvers. Thanks for the guidance, everyone.

[Larry Gibson]

Go ahead and use the magnum primers with the 2400 in the 357. I've used them for years in my own with omplete satisfaction. Yes, many claim standard primers work better in the 357, 41 and 44 magnums with 2400 but my own extensive testing has not shown that. Depending on the make of standard or magnum primer they actually work about the same IF The load is worked up for a specific one. Switching primers with a specific load can show a difference but if the load is worked up for the primer there is no practical difference. I use magnum level small and large in all my magnum loads with 2400 and I soot a lot of it in all 3 cartridges. Just work up the load is all I'm saying and you'll probably be satisfied with the results.

Larry Gibson

[44man]

There really is Larry. Not so much with SP but take the .44. No matter the powder LP mags have always tripled groups. Working loads has never worked.
Same as working with a standard primer in a larger case, no slow powder load EVER will work better with the wrong primer. I get ignition into the .500's with standard primers but not accuracy, no amount of load work will fix it. Same as the .44 with mags, load work will not fix it.
The SP and SP mag is not the same and since I no longer shoot the mouse guns, I can't say for sure but why a mag SP with fast powders? It is a small case. Do you NEED the mag with 296? Nobody can answer that. It is all book reading because it says a SP mag. If you load Bullseye in the .357, why a mag? The .38 SP does not call for one. Does 2400 NEED a mag?
We need tests with the .357 that I can't do. Accuracy tests, not go bang stuff. You can light the .357 with paper caps.
Need a dedicated .357 with a scope from a rest to test. With the SP primer there might be no difference but after thousands of tests I have concluded the LP mag in the .44 is worse and load work will not help.
Is there anyone with a set up to test?

[Larry Gibson]

44man

I have done dedicated tests with scoped Contenders measuring velocity, pressure and accuracy (50 & 100 yards). I've also done many accuracy and velocity tests with several rifles and lots of revolvers. At the end of the day I could find no difference in accuracy between standard and magnum primers with 2400 in 357, 41 & 44 magnm cartridges. Yes I know some swear there is but many swear there isn't. I've never been able to prove a difference. You might take a look at the test I did on 2400 (Hercules & Alliant) and see where I used the magnum primer. Made no difference.

BTW; a magnum primer or one made for ball powders should indeed be used with 296 and H110. Ample evidence alredy abounds on that.

Larry Gibson

[subsonic]

Well Jim,

A while back I was working with my .357 and AA9 and found that magnum primers opened groups regardless of the load, so I would say you're onto something.

This was a 6" 686 with a 1" ultra-dot. And I may not be the best shot, but I can shoot.

I'm about ready to go chasing accuracy with that thing again using H110 and 175gr Ranch Dog boolits, so I will surely test both kinds of primers.

I saw the same thing in my .45 Colt with H110, but no ultra-dot, just irons @ 25yds. I had done this same test previously with H4227 and found the same thing in that revolver. Standard primers closed up the groups.

[cbrick]

Were getting a bit off track from the OP using BE & mag primers with questions on velocity readings but . . .

I'm about ready to go chasing accuracy with that thing again using H110 and 175gr Ranch Dog boolits, so I will surely test both kinds of primers.

Please post the results.

I haven't done much in the 357 with 2400 but I have done extensive long range testing with H-110, H108, V-110 in my FA wearing a 10X Burris & grouping at 150 meters. Groups were decent with standard primers but with H-110 both groups and chrono numbers were cut in half with no changes to the load other than switching to CCI 550.

In the 41 Mag using V-110 (a stick powder) & standard primers shot honest 2 1/2 inch groups at 150 meters (scoped from the bench). Heavy doses of harder to ignite ball powders benefit from the mag primer.

Rick

[44man]

I no longer have contenders either but wonder if there is a difference in how primers work between them and a revolver? I always felt the revolver was the problem.
It was back in the late 70's when I started using a SBH for IHMSA that I switched to the Fed 150 and have used them ever since in the .44. I use nothing but 296.
I went to them in the .45 Colt but WW primers work very well in it but found the full mag opened groups.
Made a test in Ohio once at -20* and still shot better with the 150. Both groups opened but the 150 was still smaller. However, the WW primer is not bad.
Now I am working with a Marlin 30-30 with the RCBS 150, using 4759 and found the Fed 155 is better. I use the 155 in the 45-70 revolver, .475 and .500 JRH also.
Then I had to work with a few .454's for friends and found starting loads of 296 failed to light with any SR and SR mag I tried, had to load near max or over. I cut down .460 brass and tried a Fed 150, all charges lit clear to over 55,000 psi. The 155 was more accurate.
Both 4227's stay away from my .44's, too many heat problems.
I also found a SP standard primer is better in the ACP, REALLY better in the revolver.
My primer tests have never ended and I spend weeks with each caliber and retest with any changes.
H110 or 296 does not need a mag primer in the .44, just keep the boolit in place and apply heat.

[subsonic]

I think it has to do with the jump to the rifling....