Reducing SDs

[ptf18]

Fellows: This is a general question pertaining to reducing SDs during load developement.

What do you all do to make large changes in your SD measurements.

For example. If I start with a load that has a SD of 25 ( I just picked that # out of the air), what would you do first to reduce that?

Of course the load (if possible) should be based on what others MAY have found to be a GOOD load so you have a starting point.

 

[kelbro]

Simple, reduce your ES.

 

[d. michael]

i too am interested in reducing ES & SD what are some things to try to achieve this??

 

[ptf18]

What Im asking is what items would bring large positive changes to the reduction of ES and SD.

Obvious would be the powder charge. If so how much of a powder charge change? Is there a general rule say 10% or 20 % or something else.

 

[Keith Glasscock]

Fixing ES or SD problems is a matter of doing some investigating.

Brass: are they all the same capacity, brand, and of identical neck tension?

Powder: are the charges weighed to an adequately tight tolerance? Is the load working within the "personality" of the powder brand?

Primers: are they all seated with the same preload against the bottom of the pocket?

There are plenty more, these are the obvious ones

 

[Alex Wheeler]

I have never had a hard time getting low es. If all your prep is good, powder charge and seating depth consistant, neck tension consistant, and you test your loads at 300 yards or farther you should have a good es. I test my loads at long range, so for it to shoot good it will have a low es. Keep tuning, and try different powders until it shoots well at long range, you will have a low es.

 

[CaptainMal]

Listen to the above.

Interesting but I just reduced my normal Dasher charge .2 gr. For some reason the ES went <10 for about 8 test shots. I took it to 300 yards and, in the wind, shot .5's.

Loved to say I used it to win the local 565 match last Saturday but I used the old load because I had many already loaded. Further testing is coming up but all the issues Zfastmalibu spoke of are where you should be looking.

Oh...make sure you are using a good chronograph under good conditions. Many times they are not that repeatable.

 

[broncman]

When I annealed after every firing to get consistent neck tension, and did a ladder powder test .2 of a grain increments with 2 different primers, I got in the single digits with ine primer, low teens with another using same powder.

There is usually a optimum charge weight/case capacity thing going on along with the other tunable factors such as depth, neck tension etc.

I will say that with one of the heavier 30 caliber bullets, I had very low ES, but recoil management was killing my group consistency...