Acceptable ES/SD - 38/357

What extreme spread (ES) and standard deviation (SD) do you find adequate in your 38 Spl / 357 Magnum loads? I usually test factory ammo for their ES/SD and attempt to better these with my handloads…which in 38 Spl +P isn’t too hard to do. I usually aim for ES below 50 and SD below 15…I also find that the higher I run my loads the tighter my ES/SD become…powders which I obtained lowest spreads in 38 Spl +P using 158 gr cast are Power Pistol, BE-86 (best accuracy) and W231. In 357 Mag with 158 gr and 170 gr +/- Keith’s in upper mid range velocities, N340 has given me the tightest spreads and best overall accuracy.

Please tell me your experiences.

ES/SDs of less than 50/15 fps are good to strive for with 38 SPL +P loads chronographed out of revolvers. With 38/44 and 357 Magnum level loads ES/SDs of less than 75/30 fps is more realistic. This is with 10 or 12 shot tests. Tests of less than that, especially 3 - 5 shot tests, are meaningless for ES/SDs and can only give an idea of the velocity level.

Thank you Larry

Personally I dont really watch these numbers. They only tell part of the tale.

I load to safe pressures and acceptable accuracy. What that happens ta be for anything else isnt much of a concern.

So good if ya wanna experiment and see what ya can achieve good on ya but just offering ya dont need to get all wrapped up in them being "perfect". As long as you can achieve a velocity you want, with accuracy to meet your needs. Is more really required?

CW

Measure group sizes first, then look at ES and SD numbers if you still feel a need to do so.

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Originally Posted by lotech

Measure group sizes first, then look at ES and SD numbers if you still feel a need to do so.

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What lotech said...

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Originally Posted by lotech

Measure group sizes first, then look at ES and SD numbers if you still feel a need to do so.

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I've learned to do just the opposite. I'll chronograph a small incremental test of charges (usually just 5 shots) of a powder with a certain bullet looking for the spot where the ES/SD get smaller. That tells me the point where the powder is igniting and burning efficiently. I then will load incremental tests of 10 or 12 shots if for a revolver from that point up to a "max" load and then chronograph and test on target at the same time. If i find an increment that gives a good group and has a small acceptable ES/SD then I will load 25 or 50 round of that for an additional accuracy test before deciding if it is a good load or not.

After years of testing, I've found this method saves a lot of time, effort and components. This method will get me where I'm going faster or will eliminate that powder early on before too many trips to the range are made and components wasted. Yes, in days [actually years] past I've shot some fairly decent 5 or 6 shot groups at 7, 15 and even 25 yards with loads that, when chronographed, gave ES of 150 - 200+ fps and eventually proved to be very poor loads except for close range "blastin'".

All that one decent group showed me was I got lucky..........and should have used and listened to the chronograph.

So, where does one find what acceptable ES/SD's are for a certain calibers? In other words, for .45's or .223's, or any other caliber. Is there a given chart or what? I have never delved into this, I've only experimented with varying powder charges to obtain the best groups, then varying seating depths. I have a couple chronographs but have never used them. I just paper punch but I'm open to learn new things, never shot through a chronograph so I'll start with the older one first, just in case....

Slim

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Originally Posted by Larry Gibson

I've learned to do just the opposite. I'll chronograph a small incremental test of charges (usually just 5 shots) of a powder with a certain bullet looking for the spot where the ES/SD get smaller. That tells me the point where the powder is igniting and burning efficiently. I then will load incremental tests of 10 or 12 shots if for a revolver from that point up to a "max" load and then chronograph and test on target at the same time. If i find an increment that gives a good group and has a small acceptable ES/SD then I will load 25 or 50 round of that for an additional accuracy test before deciding if it is a good load or not.

After years of testing, I've found this method saves a lot of time, effort and components. This method will get me where I'm going faster or will eliminate that powder early on before too many trips to the range are made and components wasted. Yes, in days [actually years] past I've shot some fairly decent 5 or 6 shot groups at 7, 15 and even 25 yards with loads that, when chronographed, gave ES of 150 - 200+ fps and eventually proved to be very poor loads except for close range "blastin'".

All that one decent group showed me was I got lucky..........and should have used and listened to the chronograph.

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Agree that you must fire more than a group or two to find a good accurate load. I've never found firing groups at less than 25 yards to be a good use of components. Sorry loads will often group fairly well up close, i.e., under 25 yard. I never work up a load without chronographing, but my main interest is in average velocity. If the load doesn't shoot well, then I might consider ES and SD numbers, but I never put too much credence in these figures, just a reasonable amount and go from there.

When checking a load for accuracy in a revolver, I load 25 rounds. I put up two targets at 25 yards, one atop the other and fire five shots. I remove the top target and replace it with a clean one, and fire a second group. I repeat this sequence until I have shot all 25 rounds and have 6 groups--five 5 shot groups and one 25 shot group. The 25 shot group is the pudding that proves the pie. I guarantee it will be bigger than most if not all of the 5 shot groups.

For my purposes, if there is only one flier, I'll write it off as a "whoopsie on my part. If there are two fliers, I'll look very closely at the groups to determine if there is anything that I can see to explain it. Out of round bullet holes, or maybe two groups where my point of aim was slightly off. If I find an explanation of that sort, I'll react accordingly. Out of round, I'll be checking my cylinder throats and boolits for proper fit. Misplaced sight picture, I'll just figuratively slap my fore head and tell myself not to do that. If there are three or more fliers, that dog won't hunt. Either the gun or the load ain't right. I won't be loading anymore of those for that gun.