Low velocity in .357 load? How come?

Shrinkmd · Jul 17, 2011

I made up some different strength batches of .357 Magnum with the following:

New Starline .357 brass
Montana Gold 125 gr JHP
Federal SP primers
Alliant 2400 (recent manufacture)

These were shot from a 627 PC 5" V-comp (with the comp installed, but it is after the barrel ends, so in theory isn't affecting it like a port in the barrel, right?) It was warm, about 85 degrees or so.

16 gr 2400
High: 1324
Low: 1204
E.S.: 120
Ave.: 1249.3
S.D.: 36.7
95%: 29.2

16.5 gr 2400
High: 1285
Low: 1197
E.S.: 88
Ave.: 1255.1
S.D.: 26.9
95%: 21.4

17 gr 2400
High: 1309
Low: 1209
E.S.: 100
Ave.: 1272.8
S.D.: 32.5
95%: 25.8

So the velocity isn't really going up much despite 0.5 gr increments in powder charge. 1 gr of 2400 only adds 20 fps???

Granted, these are only 10 shot samples, so I will retry this another day at the range when I have more time. Do these results make sense? Lyman says you can go to 17.7 gr 2400, and Alliant's GDHP data lists max at 17.5.

Given that they aren't going any faster, should I try working up any more or call it a day? Lyman 49th says these should be going 1478 with the 17.7 load out of a 4" universal receiver. Are the Montana Gold bullets too hard, so they are slowing down in the bore? I know you're not supposed to use magnum primers with the 2400, but the data from Lyman says they use CCI 550's with all the loads.

Of course, now that I look more carefully, the Alliant data lists 1409 out of a 10" barrel, wheras Lyman says 1478 out of the 4" universal receiver. I'm even more confused. By Alliant's data, my results don't look too bad, considering I'm missing 5" of barrel as well as having a cylinder gap.

So what kind of chrono results are people getting from similar loads?

ssyoumans · Jul 17, 2011

6" GP100, 60 degrees, 850' above seal level.

16.0gr 2400, Rem 125gr JHP, 1.570", 1453 fps

I'll update with some more data later. I seem to recall getting within 15fps same with same powder load whether using 125gr Rem JHP or 124gr Montana Gold. That was within the SD, so no difference in my opinion.

35 Whelen · Jul 17, 2011

I'm no ballistician, but I think 2400 might be a hair slow for a 125 gr. bullet. But if you insist on using it, I'd put a pretty hefty crimp on the bullet to allow the powder a couple nanoseconds more time to burn. I also wouldn't hesitate to use a magnum primer if I thought it would help. Sure can't hurt anything.
Also, I used to use a Chrony chronograph and I'd get weird reading likes this that didn't make any sense. I switched to a CED Millenium 2.
35W

Shrinkmd · Jul 17, 2011

Also, I used to use a Chrony chronograph and I'd get weird reading likes this that didn't make any sense. I switched to a CED Millenium 2.

And that is what I am using as well, although just the regular screens and not the IR set. Does that make a difference in the inherent accuracy of the thing? Also, does it matter if you shoot straight across, or at some slight angle. I get tired shooting the exact same target, but come to think of it perhaps I should.

I forget my geometry, but given the small change in angle to still safely shoot through the screens, would two targets (printed on copier paper) next to each other matter?

bfoosh006 · Jul 18, 2011

+1 on a good firm crimp, and move your chrono back to 15+ feet when firing magnum handguns. The muzzle blast will mess with its readings.

gamestalker · Jul 18, 2011

I honestly feel that the one shot samles are actually giving you some false or unreliable comparisons. I shoot a lot through my chrony, and even though I weight every powder charge, trimmed all brass to the same exact length so as to achieve consistent crimps from one cartridge to the next, seated the same bullets to as precise same lengths as possible due to olgive inconsistencies, used matched head stamps, my velocities will range from +/- 35 fps, or more. And depending on the projectile weight, brand, and type these variances can go up or down rather significantly.
Over the years I've surmised that the brass that has been loaded the most, and even close to it's final loading, has provided the most consistent results, as opposed to newer brass. In addition to this observation, I've noticed Remington, being a softer brass in comparison to Federal or Winchester, delivered a bit more consistent velocity. This observation of mine has been pretty consistent with just about every cartridge I've loaded for.
Try using more rounds to average your fps reults and I think you'll see some numbers that will make a little more sense to you.

Steve C · Jul 18, 2011

With slow powders like 2400 a .5gr increment is only +/- 3% of the load and is a relatively small increase in the charge considering the difference between start and max load is 10% for most powders, exception being H110 , W296 and the like.

I've always used a faster powder that 2400 with 125gr bullets, reserving 2400 for 140gr or heavier. Best 125gr loads have always been with Blue Dot. Powders of similar burn rates between Herco to AA7 should give you better consistency (lower Std. Dev. and smaller range) that should translate into better accuracy.

ssyoumans · Jul 18, 2011

ssyoumans said:
6" GP100, 60 degrees, 850' above seal level.

16.0gr 2400, Rem 125gr JHP, 1.570", 1453 fps

Additional data, chrony at 10'
6" GP100 16.0gr 2400, MG 125gr JHP, 1.575", 1516 fps
6" GP100 16.0gr 2400, Rem 125gr JHP, 1.575", 1448 fps
3" SP101 16.0gr 2400, MG 125gr JHP, 1.575", 1351 fps
3" SP101 16.0gr 2400, Rem 125gr JHP, 1.575", 1339 fps

I use to load Blue Dot before Alliant issued the statement not to use BD with 125gr bullets. I had loaded 14.0gr for 1526 fps. At the time 14.5 was published max, but I ended up pulling those loads as they showed signs of excessive pressure, sticky extraction and flattened primers. Reloaded at 13.0gr for 1443fps and they shot fine. I had always used BD for 125gr 357's up until the instability warning came out. Interesting that Lyman 49 still publishes a BD load with 125's.

All data with CCI Small Pistol Primers (no magnum).

Something must be wrong with your chronograph or powder or crimp because I am getting higher velocity out of a 3" barrel with a full grain less powder than you and your 5" barrel.

2zulu1 · Jul 19, 2011

Here's some old 2400 (not recent manufacture) data from Sierra #2, 1978 and Speer #10, 1979.

Sierra #2 - 2400 - 125gr JHP 14.8s to 19.0grs

Speer #10 125gr JHP - 2400 17.5grs to 19.5grs

I chronographed some old 2400/125gr Sierra JHPs in 2006, they had been in storage for who knows how many years and must have been loaded when I was carrying a M66, 1980s.

Win cases, WSPM, COAL 1.585", 5 shot strings

18.0grs
Ruger Blackhawk 7.5" 1341fps/499fpe, ES 60fps, 1.6" at 25yds (off a pickup)
Colt MkIII/6" (ca 1980) 1333fps/483fpe, ES 41fps, 2.2" @25yds
M686+/6" 1458fps/590fpe, ES 85fps, 1.7" @25yds

18.3grs
M686/6" 1602fps/712fpe, ES 59fps, SD 21fps

18.7grs
M686/6"
1647fps/753fpe, ES 58fps, SD 23fps

No cylinder ejection problems.

This particular M686 has a faster than average barrel, typically averaging faster than 100fps compared to the Blackhawk and Colt. with most, but not all powder/bullet weight combinations.

FWIW, Lyman #45, 1970, did not test 125gr jacketed bullets, jacketed bullets did not arrive 'til the late 60s; I'm not sure when the 125 JHPs began production.

Bob

Shrinkmd · Aug 9, 2011

Could it be the Montana gold bullets are "slower" than other jhp's? I thought I read that they have a slightly harder jacket.

So what would be a better powder to try and get better performance out of 2-5" barrels with these bullets? Unique or Power Pistol?

918v · Aug 9, 2011

You might have a slow barrel. You might also need more neck tension and crimp.

steveno · Aug 9, 2011

sometimes the chronograph just won't give you what you are expecting but that is the way it goes sometimes. it looks like some things have been mentioned to look at however.

gamestalker · Aug 9, 2011

Thr next step in performance up grade is H110 or 296. I load exclusively with those two for every bullet weight in my .357's. Many will argue that these loads will loosen your gun up or even cause the forcing cone to fracture, but in all the years of loading mostly 125 gr. jacketed with these powders, I have yet to experience any negative effects. Even my brass life is excellent.
A couple words of advice though when using those powders. Make sure you use a magnum primer and a stout crimp. Without the good stout crimp you'll have bullets jumping out of the mouths, which we know can cause more than one problem, cases igniting that aren't in battery with the barrel, and the cylinder getting locked up.
Also, don't reduce those pwders below listed minimums or strange things can happen, like unpredictable high pressure spikes.

GP100man · Aug 9, 2011

Take a step up in powder burn speed , HERCO , IMR 800x & CLAYS UNIVERSAL are better suited to wring out a 125gr bullet in the 357.

Low velocity in .357 load? How come?

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