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Thread: What's an Acceptable ES?

  1. #1
    Boolit Mold
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    What's an Acceptable ES?

    Like the question says...

    Back story: I'm used to loading .40S&W for my Glocks, and I'm used to seeing ESs in the 30-60fps range, and SDs in the teens or twenties, if not single-digits (with both factory and reloads).

    So, to me, an ES over 100 or an SD over 30 looks like something ain't right.


    You may have seen my ongoing thread about Trail Boss in .38Spl... I'm seeing ESs 100-150fps, and SDs in the 30-60fps range, which I figured was a problem.
    (NB: This isn't just my problematic reloads, but also Speer's 125gr +P Gold Dot.)


    Then, last night, I was reading the September issue of Shooting Illustrated (best gun mag out there, IMO), and looked closely at the velocities from the revolvers they tested...

    The review of the S&W 610 in 10mm (I want one, badly) looks good/normal to me: Of fifteen loads tested, the highest SD is 22, and only three loads had ESs in the low 40s (everything else was under 40).


    The review of the King Cobra: Of nine loads, the middle (#5) has an ES of 48, and the two highest were 63 and 71. No SDs were listed... That seems OK, too, if not as good.


    Then, the (glowing!) review of the 4" Ruger SP101 in .327 Fed Magnum blew my mind: Of a dozen factory loads tested, four had SDs in the 50s. Six had ESs over 160... Two over 200!

    (I now feel a bit better about my own inconsistent handloads!)

    There's no mention at all in the article about this inconsistency, which makes me wonder if this is "normal" or acceptable for long skinny revolver cases like .327 or .357 (or .38Spl).


    So, what's an acceptable threshhold or tolerance?

  2. #2
    Boolit Master

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    I shoot for ES under 100 and SD under 20 in plinking ammo, usually check 10 rounds at a time loaded with the same process the rest will get. For bench ammo I try for ES around 15-20 and SD as low as I can get. But that ammo is loaded in a much different method. Also, I think some powders just will not perform that tightly in some pistols.

  3. #3
    Boolit Grand Master
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    ES is often very high for long skinny revolver rounds with partially filled cases and the 327 is a particular offender in that regard. A better design would have been the 32 H and R case loaded to higher pressure but this cannot be done for obvious reasons.

    I have often thought that one cannot know true potential ES and SD unless one shifts the powder to the front and back of the case to truly model possible extremes in powder loacation, which more accurately models potential variation.

    A 9mm case with a 147 grain bullet is hard to beat in that regard....tiny case small area for powder to be confined to, high pressure. Low ES and SD’s result. Reverse those conditions and partially fill the case with powder and the numbers get worse.

  4. #4
    Boolit Grand Master


    Larry Gibson's Avatar
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    ES and the attendant SD in revolvers is many times larger than using the same cartridge and load in a solid breach rifle or handgun. The variables creating the larger ES/SDs in the revolver are the bullet mass, the longer throats (many times larger than the bullet), the barrel/cylinder gap and most often a much lower load density. The longer throats and a larger barrel/cylinder gap also alter the time/pressure curve and specifically the rate of climb to efficient burn. Slower burning powders and/or less than optimum pressures for efficient burn (such as with your Trail Boss loads in your 38 SPL with the very light bullets you're using) also increase the ES/SD. Additionally, most revolver cartridges vs semi-auto cartridges have much lower load densities with low end loads and that alone most often contributes greatly, even with easily ignitable fast burning powders, to larger ES/SDs.

    Honestly all the ES/SDs you mention are not really "out of line", especially the ones for your short barreled revolver.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  5. #5
    Boolit Grand Master


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    Quote Originally Posted by Bimmer View Post
    Like the question says...

    Back story: I'm used to loading .40S&W for my Glocks, and I'm used to seeing ESs in the 30-60fps range, and SDs in the teens or twenties, if not single-digits (with both factory and reloads).

    So, to me, an ES over 100 or an SD over 30 looks like something ain't right.


    You may have seen my ongoing thread about Trail Boss in .38Spl... I'm seeing ESs 100-150fps, and SDs in the 30-60fps range, which I figured was a problem.
    (NB: This isn't just my problematic reloads, but also Speer's 125gr +P Gold Dot.)


    Then, last night, I was reading the September issue of Shooting Illustrated (best gun mag out there, IMO), and looked closely at the velocities from the revolvers they tested...

    The review of the S&W 610 in 10mm (I want one, badly) looks good/normal to me: Of fifteen loads tested, the highest SD is 22, and only three loads had ESs in the low 40s (everything else was under 40).


    The review of the King Cobra: Of nine loads, the middle (#5) has an ES of 48, and the two highest were 63 and 71. No SDs were listed... That seems OK, too, if not as good.


    Then, the (glowing!) review of the 4" Ruger SP101 in .327 Fed Magnum blew my mind: Of a dozen factory loads tested, four had SDs in the 50s. Six had ESs over 160... Two over 200!

    (I now feel a bit better about my own inconsistent handloads!)

    There's no mention at all in the article about this inconsistency, which makes me wonder if this is "normal" or acceptable for long skinny revolver cases like .327 or .357 (or .38Spl).


    So, what's an acceptable threshhold or tolerance?
    Now 327 federal is something I can help with. First my own opinions of ES are always changing. I do not worry about SD, although I often mention it, as my chrony calculates it for me. I am ok with wider ES than many rifle shooters are. 60-70 fps is ok. Like you, I do not like to see 100 fps+, and that usually indicates problems.

    Now onto 327 federal. The best shooting factory load I have found is the Federal AE 100 grain (the 85 grain version sucks). This load is capable of 4" groups at 50 yards in my 5" GP100, and runs about 1650 fps. Now the scary thing is the extreme spreads, they are up around 160 fps. I disagree with 35remington in that a partially filled case is to blame. In the case of the Federal AE factory load, the powder is compressed, you can shake them and do not hear any powder moving.

    Now I have done quite a bit of chrony work with the 327 federal. I've said it over and over, but the biggest culprit most of the time is a too light bullet, and guys looking for lazer fast velocity. The combo of slow powder, light bullet, lesser neck tension as a result, and other variables do not make good ammo. I went out of my way to cause problems with air space in 327 federal. Like I said, i went as low as 1 grain of powder, and the extreme spreads were very low. That same 100 grain bullet with strong loads of AA#9 has ES in the 90's. Change primers, and it can come down to the 40's.

    While air space will always result in some position sensitivity, it is not a cause of erratic ignition in the case of fast powders. I have not worked with trail boss, but most fast powders work great with poof loads.

  6. #6
    Boolit Grand Master popper's Avatar
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    I don't worry about the statistics, let the target show the results. ES is highest and lowest fps, SD is the distribution of the fps. They really only relate to LOADING procedures, i.e. how identical are your loads? I can't shoot long range pistol accurately anyway, never chronyd a pistol load either. Rifle is different. SD 20 is reasonable.
    Whatever!

  7. #7
    Boolit Master


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    Quote Originally Posted by megasupermagnum View Post
    Now 327 federal is something I can help with. First my own opinions of ES are always changing. I do not worry about SD, although I often mention it, as my chrony calculates it for me. I am ok with wider ES than many rifle shooters are. 60-70 fps is ok. Like you, I do not like to see 100 fps+, and that usually indicates problems.

    Now onto 327 federal. The best shooting factory load I have found is the Federal AE 100 grain (the 85 grain version sucks). This load is capable of 4" groups at 50 yards in my 5" GP100, and runs about 1650 fps. Now the scary thing is the extreme spreads, they are up around 160 fps. I disagree with 35remington in that a partially filled case is to blame. In the case of the Federal AE factory load, the powder is compressed, you can shake them and do not hear any powder moving.

    Now I have done quite a bit of chrony work with the 327 federal. I've said it over and over, but the biggest culprit most of the time is a too light bullet, and guys looking for lazer fast velocity. The combo of slow powder, light bullet, lesser neck tension as a result, and other variables do not make good ammo. I went out of my way to cause problems with air space in 327 federal. Like I said, i went as low as 1 grain of powder, and the extreme spreads were very low. That same 100 grain bullet with strong loads of AA#9 has ES in the 90's. Change primers, and it can come down to the 40's.

    While air space will always result in some position sensitivity, it is not a cause of erratic ignition in the case of fast powders. I have not worked with trail boss, but most fast powders work great with poof loads.
    given the infinite number of variables in producing an accurate load. let your target do the talking. Dead center with a .30-30 beats a near miss with a .458 mag.

  8. #8
    Boolit Grand Master
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    Now, I never said that ES couldn’t be high with a case full of powder, and I have no doubt the light 327 bullet is playing a role in high extreme spreads in velocity when slow powders are used.

    But if you want to see extreme spreads get even worse than you are mentioning, especially in relation to the velocity obtained, try a partial case full of powder, low pressure, and let it shift in position from front to back. The “do it all” appeal of the 327 may tempt some to load the cartridge as I have mentioned in an attempt to make a 32 Long out of it and this does not turn out particularly well.

    This applies to a number of the long revolver cartridges...38 Special, 357 loaded light, 45 Colt, etc.

    When poor choices of powder are made, such as Universal in the comparatively short 32 Long, velocity variations can reach 140 fps or more with powder shifted front to back, and this with loads that are getting only 750 fps in the first place. As a percentage of variation that is pretty high for something that approximates standard pressures for the cartridge. When the 327 is loaded to similar velocity levels and tested the same way the numbers are even worse, exactly as expected.

    Point I was going after in the general and specific sense when applied to any cartridge is that having a lot of airspace does not help.

    To some limited degree better powder selection helps, but there are limits to that as well. For example, Titegroup lets extreme spreads run as low as around 50 fps when tested as I have described using standard seating depths with 158s in the 38 and upper standard to Plus P pressures, but lighten the bullet weight substantially and ES climbs with supposedly “insensitive” Titegroup as well.

    Know those factors that tend to lower ES and apply them. That is all you can do.
    Last edited by 35remington; 08-21-2019 at 10:53 PM.

  9. #9
    Boolit Grand Master


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    I consider position sensitivity and extreme spread to be two different issues, although one can effect the other.

    A 327 federal most certainly can work great loaded to 32 long levels. It's not hard to do at all. 45 colt is supposed to be light loaded, so I'm not sure what you are saying there. 357 magnum works fine with a 000 buckshot (70 grain), and 38 special is a pipsqueak as it is.

    I know what you are trying to say though, although my testing has shown no problems as a whole. 45 acp as an example is no better than 45 colt loaded to the same levels, at least in my guns. Just look at the rifle shooters. 10 grains of Unique in most rifle cases is a common load. That's something like a 15% case fill, and shoots fantastic.

  10. #10
    Boolit Grand Master
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    I do recall sometime back Mike Venturino mentioned shooting 32-20 factory loads. With the powder at the back the expected sharp crack and close to expected velocity was obtained.

    Letting the powder shift by the bullet before firing resulted in them sticking in the barrel. He mentioned that in Handloader magazine a few years back, as I recall.

  11. #11
    Boolit Master
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    I’m loading 38 spl 158 gr cast and pc’d boolit at 3 gr BE, at about 820 fps. Watching the lawn steel group down in Florida shoot, they tilt pistol up and shake to get powder back by primer and are very pinpoint accurate out to 70 yards shooting steel silhouettes. Haven’t been looking at SD or ES
    Will next time I go to shoot which is about 3 times a week.
    Last edited by Hossfly; 08-21-2019 at 11:04 PM. Reason: Spelling

  12. #12
    Boolit Grand Master
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    One only knows if position sensitivity is occurring if one induces it, and since it is possible to shift powder forward when drawing the gun from low ready or a holster, if one does not specifically test for it one cannot quantify the effect.

    I consider position sensitivity as the major player in extreme spread that it is and specifically model it. In long cases position sensitivity, lower pressures and ES are directly related.

    When using 32 Long equivalent loads in the 327 case I specifically shift the powder rearwards due to my previous findings if I have any reason to suspect it has bunched up near the bullet.

  13. #13
    Boolit Grand Master
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    45 ACP is very substantially better than standard pressure or even somewhat higher pressure 45 Colt in terms of reduced ES in my very specific testing for same. The why is obvious....the smaller ACP case has less room for the powder to slop around. It is also running at higher pressure in most instances when speaking of SAAMI specs.

    What is remarkable (not saying that is the case with those here) is the number of individuals that overlook position sensitivity as a factor in long cases and high ES especially at low pressures.

    Can’t count the number of times I have read or had someone assure me in person, for instance, that Unique is “position insensitive.” On a few occasions I’ve placed that under a 158 in a 38 Special case and ran it over the chronograph with witnesses. Opinions suddenly changed.

    That is a big player in high ES, to reiterate my point. Run it in 9mm and it does wonderfully, but then so does nearly everything else.

  14. #14
    Boolit Grand Master
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    So to further belabor the point, I am purposefully trying to find the maximum possible ES that can occur with a given loading, mostly for the purpose of seeing if it is possible to reduce it.

    And there is more than on way to reduce it. Switch bullets, switch powders, shift the powder before shooting. Or simply recognize the conditions where variation matters and where it does not, and don’t care when it does not matter.

    Following up on Larry’s commentary, one could pursue a tighter fit of bullet diameter to cylinder throat diameter to reduce ES in revolvers. Substitute Bullseye for Unique.

    For seven yard defensive shooting practice it probably doesn’t matter so much.

  15. #15
    Boolit Mold
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    Thanks, guys... This is helpful.

    The consensus seems to be that I shouldn't be too worried about the "stats." I'm OCD enough to want low numbers just for their sake, and I sometimes plink at 25yds, so more consistency would be better...

    Also, some of the light loads I'm trying vary so much in velocity that one round is double the energy of the next, which is disconcerting: It feels like a squib load (but it's not).

  16. #16
    Boolit Grand Master


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    25 yards you will never, ever notice a difference. The only reason I check at all is because I like to have a day or two a year of long range handgun shooting, starting at 100 yards, moving out to 5-600. Usually in the spring and fall when the farm fields are empty and dry.

  17. #17
    Boolit Grand Master
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    If you want low extreme spreads load 3.5 grains of Bullseye or Titegroup under a 148 cast wadcutter. This is as good as it gets in the 38 Special, which is quite good indeed.

    Still standard pressure. About 870-880 fps from a four inch revolver

  18. #18
    Boolit Grand Master

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    A lot can affect extreme spreads in firearms. Case thickness, case hardness, crimp, primers, flash holes size center and form ( sharp edges burrs). powder type and how it fills the case. And then there's the firearm, barrel length ( I normally see higher es from short barrels) hammers striking the primers force, and on revolvers barrel cylinder gap. Sorting brass by maker and lot number helps, looking for the best primer also can lower es, crimp, seating tension.

    Finding the appropriate powder for pressure level barrel length also helps. This is in relationship to the primers also.

    Ive been shooting BPCR with Black powder and heavy for caliber bullets in the 1150-1200fps range. With flash holes deburred and a slight bevel, T flash holes uniformed, and the right compression on the powder I can get ESs in the 10-13 fps range or SDs of 3-4. These rifles have longer barrels of 30-34" also. I anneal every other firing and don't crimp. Light neck tension ( hand seated bullets).

  19. #19
    Boolit Mold
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    Quote Originally Posted by megasupermagnum View Post
    25 yards you will never, ever notice a difference.
    I just ran the ballistics...

    GunData won't allow a muzzle velocity of less than 500, so I compared 500 and 700fps, with 75gr wadcutters (nevermind that it says 148gr, I just selected that to get a comparable BC).

    This says 1-1/4" verticle difference, plus 1/4" difference in wind drift, at 25yds.

    Click image for larger version. 

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  20. #20
    Boolit Grand Master


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    I should have qualified, I meant the 60-100 fps spreads we were talking about. I lost count how many fantastic shooting loads have ES around 70, and how many poor ones have ES in the teens. 200 fps ES is bad, something is wrong there, and you will notice just by recoil something aint right.

    Now, you posted a ballistics table of drop, not trajectory. Since you are sighted at a distance beyond 0, the effect will be less on target. I do believe you should increase your trail boss load to 4 grains, which is ultimately what all these threads are about. Velocity spreads is one thing, but it's another to be flirting with a stuck bullet.

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