Topic: Reducing SD and ES of your reloads

[ekuo]

I read a few threads on here where people have mentioned getting single digit standard deviations (SD) and some pretty low extreme spreads (ES) of their reloaded pistol ammo. 

I periodically chrono my reloads to make sure I'm making the proper PF and to see what kind of effect different temps have on my reloads.  I typically shoot a 15 shot string, then calculate my average velocity and SD.  I usually get a SD in the low teens, but would like to improve on that if possible.

For those of you that get single digit SD's, would you be up for sharing your tricks and tips? 

Thanks!

[J Mack]

Assuming pistol cartridges.
For me the biggest gains come from quality of components and consistency of process!
For example good brass can be made into quality brass through brass prep or quality brass can be purchased but at the end of the day what you are looking for is consistency.

SD numbers are affected by things like internal case volume; consistent neck tension is impossible to achieve with cases of different manufacture, length or firings, simiauto’s are a challenge at time’s by the nature of the beast not enough crimp and you push bullets back into the case and too much crimp and accuracy goes out the window. I have not had any luck with plated bullets I don’t know if it’s because the inconsistencies in the copper plating or the construction but my most consistent loads come from hard cast lead or quality jacketed bullets.

As an experiment take fifteen new pieces of good brass from the same manufacture and trim them all to the same MINUMIM length for your cartridge load them all with your powder to the .001 grain and seat the bullets to the .001 inch then crimp with the lightest crimp that will reliably cycle in your pistol and see if your SD numbers come down

[ekuo]

Yes, this is for pistol (.40SW and .45 acp).  But it's also for USPSA and IDPA-type shooting, so we're talking volume.  Can't say that I want to trim that many cases per month! 

The reason why I ask is because when I work up or check my comp load, I want a load that consistently gives me a velocity where the average of the string, minus 2 std deviations, will be at 170 PF (i.e. 850 fps for a 200 gr LSWC .45 acp).  So, the lower the SD, the less I have to subtract from the average. 

Example:

Average velocity of a 15 rnd string:  870 fps
Std Dev:  15 fps
2 StdDev's:  30 fps

Therefore, my adjusted load is 840 fps or 168 PF (Adj Load = Average - 2 StdDev). 

I know it's probably gorilla math, but basically what I am trying to achieve is a load where 95% of the reloads will be at or above 840 fps (using the above example), and only 5% of them will be less than that. 



 

[J Mack]

Getting single digit standard deviation numbers with mixed head stamp brass on a volume progressive loader will be tricky for sure.
Some of the things I’ve done with my Dillon 650 that help my loads.
1)   I switched from a Dillon roll crimp to the Lee factory crimp; the Lee crimp is not as picky on case length and this change alone made the biggest improvement on loading mixed head stamp unsized brass.
2)   Tighten  the shell plate as much as you can and still have it run reliably , I’ve seen where guys will put bearings under the bolt and hear that this also is a big help. A tight shell plate helps with consistent COAL.
3)   I added some setscrews to my press to lock my tool head this also helped with  consistent COAL

Sorry I can’t be more help on pistol cartridges I only load a couple of thousand a year and I don’t pay too much attention to the numbers.
Good luck and please let us know if you find something.

[Nealio]

I know that the powder you use can make a difference for 2 reasons:

If you are using a light charge and the powder dump varies by a fixed amount, you will see a bigger inconsistency with those light charges.

Make sure the powder you choose meters consistently and accurately.


So for example when I was running Blue Dot I was getting a large fluxuation in charge weights, which was putting my velocities all over the place.  Since I switched to Power Pistol I see a lot more consistent charge weights and therefore more consistent velocities.

[ekuo]

Getting single digit standard deviation numbers with mixed head stamp brass on a volume progressive loader will be tricky for sure.
Some of the things I’ve done with my Dillon 650 that help my loads.
1)   I switched from a Dillon roll crimp to the Lee factory crimp; the Lee crimp is not as picky on case length and this change alone made the biggest improvement on loading mixed head stamp unsized brass.
2)   Tighten  the shell plate as much as you can and still have it run reliably , I’ve seen where guys will put bearings under the bolt and hear that this also is a big help. A tight shell plate helps with consistent COAL.
3)   I added some setscrews to my press to lock my tool head this also helped with  consistent COAL

Sorry I can’t be more help on pistol cartridges I only load a couple of thousand a year and I don’t pay too much attention to the numbers.
Good luck and please let us know if you find something.

OK.  Good thoughts.  Appreciate that.  

-I'm already using the LFCD and haven't used a roll crimp die in a long time.  I'm actually thinking that maybe I ought to try a regular taper crimp die instead of the LFCD to see if that has any improvements on the consistency of my load.
-Good idea about tightening the shell plate down.  I usually set that snug but not tight.  But I see your point on consistency.
-I've heard about people putting in set screws for their toolhead.  There is some play in the 550's toolhead where it slides into the press.  Got a pic by chance?  

Thanks

[ekuo]

I know that the powder you use can make a difference for 2 reasons:

If you are using a light charge and the powder dump varies by a fixed amount, you will see a bigger inconsistency with those light charges.

Make sure the powder you choose meters consistently and accurately.

Yeah, I'm with you on the powder choice.  Currently using WST for .40 and Clays for .45, and both meter pretty consistently based on when I do periodic checks with my scale.  Scale is checked with check weights as well. 

What I'm currently doing in my quest for consistency is:
-Keep the powder measurer at least 1/2 full when loading. 
-I clean the powder measurers periodically, and even polish the metal funnel portion at the bottom of the powder measurer.
-Clean the powder bar
-Make sure to use a full stroke
-Use the same brand of components -bullet, primers, powder.  About the only thing that is random is the brass. 

Guess what I'm looking for are ideas on technique, like the above mentioned tightening up of the shell plate and tool heads. 

Good thoughts.  Keep 'em coming if you have any ideas.  Thx

[RGinIdaho]

Good stuff.

Consistency of components is one factor. I've consistently loaded low SD, accurate ammon on progressives with mixed brass. I've seen single digit SD's in revolvers. Yeah, the equivalent of 6 different chambers in an auto pistol or rifle.  Go figure...

IMHO
Powder burn rate seems to have a larger influence on the outcome than any amount of case prep. I have turned in single digit SD's with mixed brass in auto pistols as well as rifle loads. I have also gone the anal brass prep route and found no change in SD or accuracy in some instances. I'll have to admit that many times I have stumbled onto an accurate and consistent load by sheer luck. I mean the consistent part. The accurate part is easy if the gun is at all capable.

If you notice in some load manuals,  Hodgdons, Accurate and Lyman for example; they publish a pressure for the load listed. Did you ever wonder why they stop at 46k cup when the cartridge is good to say 52k cup? That is not listed so that you know your load has less pressure and therefore room for error. Just the opposite is true. That low ball load is a bit "spikey" for lack of a better description. It has to do with the consistency of that particular powder in that particular combination of case volume, bullet weight, etc. The farther they are from the actual SAAMI spec, the more pressure variation in the combination. You will see some loads that are listed right at max pressure ratings. This is an indicator of consistency in pressures. Pressure does the work and impacts velocity figures. You can see where that is going. Pick a proven consistent combo and go from there. Sometimes you will work up a load and find low SD's all along the ladder. Sometimes only in one particular range.

A good example is working with ball powders. It was once generally accepted practice to begin low and watch accuracy and ES. You can watch a ball powder go from 100fps ES down to 10fps ES then go back up. Once you pass the 10fps, you were generally believed to be working above the maximum pressure levels consistently safe for that combination.

Primers and barrel length seem to affect SD at times. When you think about it, the entire barrel can be considered part of the combustion chamber for the powder. The temperature at which the primer operates has an impact on how fast and how consistently the powder column is ignited. Both are factors that affect burn rate... Crimp and or neck tension also impact the burn rate by increasing or decreasing the time (milli-seconds) that bullet opposes the pressure created by the burning powder. Try altering the crimp in the big bore magnums like 41, 44 and 454. You can dramatically affect accuracy and SD particularly with 296 or h110(both ball powders).

Some powders are known to operate more consistently at upper pressure limits. Others are radically inconsistent when pressures rise above a certain level.

SD seems to be a bigger factor at long range than anything else. Out to 600yds, 20fps isn't even a half MOA in .308 for most loads. 1/2MOA at 600y is 3".  At 1k, 20fps might be a deal breaker depending on the target size.

OK, a lot of thoughts, maybe some rambling and repeating concepts so, I'll quit. 

[RGinIdaho]

Ekou,
You are working toward the opposite end of the spectrum as far as load work UP! More like load work DOWN. That might be a challenge.


For the 45acp and the 200lswc.
 
Try n310, lasercast 200 lswc and winchester large pistol primers. I've gotten 10 and 20 round SD's in sorted brass from 4.2 to 4.6 grains. It will range between 825fps and 890fps depending on the load and barrel. N310 is not a cheap powder but it is clean, consistent and accurate. If you buy in bulk, it isn't too bad cost wise. The load has worked for me with other lswc but lasercast seems to be a bit harder, a little more consistent in sizing and generally a bit above the the average bore diameter in .45 barrels. The lasercast bullet and the winchester primer are definitely factors in the combo. Not as big as the powder though in my testing.

Wilson suggests this load for pistols with their accuracy guarantee. P Sweeney tested it for a book he wrote on the 1911 and found it to be the most accurate load tested over the run of mixed 1911's tested.

At one time I had six 1911s. They all shot the load extremely well. Spiff shoots it in his Glock. If my memory is correct, his groups shrank to a good bit less than half of his original load.


For power factor measurements, the lasercast that I have weighed come in at 195gr. Figure them at 200 and they might cut it close if they chrono and weight. My load went 166pf @ the IDPA State match. Closer than I planned but, it would have passed in my gun if the need had arisen.

[ida83704]

Not trying to be a wise acre here, but why the concern on SD on pistols?

Precision Rifle sure, that makes sense.
Is this to make sure you make power factor?

What is the SD on Factory full power?

[RGinIdaho]

Not trying to be a wise acre here, but why the concern on SD on pistols?

Precision Rifle sure, that makes sense.
Is this to make sure you make power factor?

What is the SD on Factory full power?

For me, it is the gee whiz factor. I like to experiment and better is, well, obviously better. Kind of like the American male mantra; bigger is better.

Other than developing SAFE, accurate ammo,at least with close range handguns, I don't worry about SD in my handloads unless it is above 20. I hate to think that one round is moving 50fps faster or slower than the last one. The faster one is the one I worry about. Why the huge increase in chamber pressure?

 I used to shoot silhouette with revolver and single shot pistol. ES and SD are contributors to accurate rounds out to 200m. I get picky there.

ES is something to consider regarding safety in all cartridges. Extreme pressure variations on an already max load and you could have issues with popped primers, case fatigue, etc.

Factory loads, I've seen SD's in the single digits. Teens are pretty common. Just glancing at my notes, I don't see anything outside of the 20's. Cheap WWB 9mm turns in a low SD.

[Steve N]

I think that once a guy starts shooting for accuracy, and I mean ACCURACY, then it becomes an obsession. My son told me that a while back. And it's true. Even my back country 22 that I carry and get dirty - some brands shoot better than others when it comes to ammo - and I have become quite demanding with all my weapons. It's a PITA as times - but what the heck - it's a personal challenge -

[ekuo]

Ekou,
You are working toward the opposite end of the spectrum as far as load work UP! More like load work DOWN. That might be a challenge.


For the 45acp and the 200lswc.
 
Try n310, lasercast 200 lswc and winchester large pistol primers. I've gotten 10 and 20 round SD's in sorted brass from 4.2 to 4.6 grains. It will range between 825fps and 890fps depending on the load and barrel. N310 is not a cheap powder but it is clean, consistent and accurate. If you buy in bulk, it isn't too bad cost wise. The load has worked for me with other lswc but lasercast seems to be a bit harder, a little more consistent in sizing and generally a bit above the the average bore diameter in .45 barrels. The lasercast bullet and the winchester primer are definitely factors in the combo. Not as big as the powder though in my testing.

Wilson suggests this load for pistols with their accuracy guarantee. P Sweeney tested it for a book he wrote on the 1911 and found it to be the most accurate load tested over the run of mixed 1911's tested.

At one time I had six 1911s. They all shot the load extremely well. Spiff shoots it in his Glock. If my memory is correct, his groups shrank to a good bit less than half of his original load.


For power factor measurements, the lasercast that I have weighed come in at 195gr. Figure them at 200 and they might cut it close if they chrono and weight. My load went 166pf @ the IDPA State match. Closer than I planned but, it would have passed in my gun if the need had arisen.

RG,
I've read and re-read your post several times, and I think (I think) I understand what you're saying.  You've posted some really good successes, so I want to understand what you're doing that gives you such consistent ammo performance. 

You believe there is a sweet-spot for each barrel that has a preferred powder and bullet combo, and I believe the same.  Varying the load +/- a tenth or two can improve or worsen things.  I saw that very effect when I was working up a load for my AR.  POI would change up/down, left/right as I changed the load.  But since I was well over minor PF (rifle) I didn't scrutinize the data other than to make sure I was over PF. 

I'm with you so far, and will try the "Wilson" load.  I happen to have a box of Lasercast 200 gr LSWC under the bench, and I'm willing to give VV N310 a try (except I will continue to call it V-V because I can't pronounce Vihtavouhri, much less spell it!).  Thx for the load info. 

But I'm not following your comment about "working towards the opposite end of the spectrum", and what you meant by "need to load work DOWN". 

I'll be at Parma on Saturday... maybe you could explain more? 

[RGinIdaho]

Ekou,
I won't make it this Saturday due to work committments.

Sorry for the info dump. I was in a hurry and didn't tie it all together as well as I could have.

What I mean by opposite end of the spectrum;

Most folks start low and work up. Typically, if they watch the chrono results they will see an increase in consistency as they work up toward a powders preferred burn rate. You on the other hand are searching for that consistency near the lower end. A really fast powder and heavy bullet might get you where you want to be.

Be careful with really fast powders and caliber heavy slugs and major PF in the .40sw. It has a reputation for taking out guns with that combo. Generally accepted advice is nothing faster that AA5 with 180ish slugs if you are going for major PF. WSF got me in the low teens and singles with 170 lswc in .40.

 45acp with it's lower pressure range, not so much of an issue in fact good target performance such as you seek is common with very fast powders. 9mm while high pressure seems to tolerate fast powders more readily because of the miniscule case capacity that remains when a caliber heavy slug is used.

[ekuo]

RG,
Thanks for the explanation.  Copy that, on the warning about .40SW being a pressure round.  I've been cautious with my .40 load workup for that reason, and that's why I chose WST over Clays for .40SW. 

Of all the powders I've used, I never had a chance to give any of the VV's a try.  So you've peaked my interest, and I plan to get a pound of it for some load testing with some Lasercast and Bear Creek moly's that I have on hand.  I'm also not adverse to upping the PF if that's what it takes to get a well performing round, so will do some testing to see if I can improve on my current load. 

Sorry you won't be at the match, but I'm sure we'll run into one another before too long. 

Later!