Dillon vs 3BR ...who has the lowest SD

[10mmShooter]

Observations after 3 hours at the range with my chronograph

I used LE Federal 180g Hydra-Shoks(P40HS1G) as my control round to check the chrono and my measuring methods. Through my Beta Master Chrony I showed 945.89 fps with an SD of 10.77 fps. I was very happy with this result as expected the premium factory round has a very low SD, and the 945 avg fps is close to the factory stated spec of 1000 fps. Test conditions were 85 degrees and 90% humidity which kills velocity.

Through out my 3 hours of testing 17 different loads in 3 calibers .38 spec, 10mm, 44 mag(all shot out of 8-3/8 686, 8-3/8 Anaconda and two 610's). I observed something unexpected, I load with a Dillon 650 and Redding Big Boss II and Redding 3BR powder measure combo. I would have expected my loads that I loaded with the single stage press should have a lower SD that the loads from my 650. It all comes down the Dillon power bar vs the Redding 3BR powder measure. I was loading Green Dot a flake powder in the Dillon and AA#5 in the 3BR. Obviously the AA #5 ball powder should meter better than the Green Dot flake you would think??.

My actual results for the 17 loads in 3 calibers showed an SD range of 9.61 fps to 18.5 fps , I was very pleased to have all my loads under 20 fps SD.

Anyone ever notice anything similiar?? The Dillon press continues to impress me.

[Houndog]

It's NOT the measure as much as technique in operating the measure that's the key to consistancy! The Dillon relies on mechanical means to dump the powder while the Redding measure relies on you being the same every time. Do you bump the measure the same every dump, or is one soft and the next one hard? I use a custom measure made by Lynwood Harrell for Benchrest, and in my opinion it's THE best measure currently available. If I do my part, it will dump powder at less than .1 accuracy, but if I get sloppy, it's all over the place! The key is consistancy!!!!!

[mike in co]

not really a valid test.....

two different powders

try 100 rounds of the same load from each setup, shot the same day same gun, alternate every 5 rounds or so so the gun in consistant.
then look at your numbers for 2 100 rd strings.

the dillon powder measure is a lic of the lee design, and is one of the most consistant measures made.

mike in co

[fecmech]

It may or not be a valid test but one thing is true about progressive presses they are constantly vibrating the powder column and IMO that leads to greater consistency. I have a Redding powder measure on my Lyman turret press that I turn as I load each round to completion. It never varies more than a tenth of a grain with any of the pistol powders. The same holds true on my CH Auto Champs with their bushing type powder measures.

[HeavyMetal]

I agree with Mike: apples and oranges comparo.

I will suggest same powder in both press's and then do as Mike suggested.

My experience is SD means squat! Low SD's are nice to look at but I have seen double digit SD's that shot very well. SD is a variable and, as far as I know, no one has demonstrated a way to adjust or predict an SD.

Since it is what it is I usually ignore it.

A different day with different Humidity and temp's and those same SD's might be triple digit!


What impress's me is group size! Velocity should be in the range of factory loads after that the ability to put it where I want when I want it is the only thing that matters.

Not critiquing your style here merely passing along my thoughts on the subject

[dudel]

My experience is SD means squat! Low SD's are nice to look at but I have seen double digit SD's that shot very well. SD is a variable and, as far as I know, no one has demonstrated a way to adjust or predict an SD.

+1 A recent article in Handloader (Charles Petty IIRC), showed better accuracy on rounds that had higher SD. This is not to say that you could not find a combination that had good accuracy and low SD. I think it just means that a low SD is a good predictor of accuracy.

I used to agonize trying to get small SDs; now I just look for tight groups, and hang the SD. Chrono is used for checking for excessive pressure when working up loads.

[Rocky Raab]

Standard Deviation (SD) is a measure of consistency, so we cannot consider it to be worthless. On the other hand, consistency of velocity and group size are not directly related. You can have great groups with a load that varies in velocity, or you can have large groups with a load that shoots the same velocity every time. You can also be great and great as well as lousy and lousy! So, even though velocity consistency is a good thing, and small groups are a good thing, they are goals to be sought separately.

The above is for handgun or short-range rifle shooting, of course. Those tortured souls trying to shoot small groups in different zip codes need not counter with their quite valid "Yeah, but..." comments.