FX 120i $597.00

[hounddawg]

Simple physics is all anyone need to know that lower SD's should mean lower vertical spreads Jugornaut. But what you cannot seem to grasp is that you don't need charges weighed to .001 grams to get low SD's. If you do your load development right you can use a Lee plastic dipper and still get low SD's

On the 4831 SC test above at 44.1 gns of powder the average velocity was 2731 FPS and at 44.5, 2728 and at @43.3 2739. Now that tells me I could load that ammo to 43.3 and be off by a full .2 grain in either direction and my velocity ES would still be below 10FPS on average. Those charges were weighed by a RCBS Chargemaster 1500 which I bought 6 or 7 years ago.

The video's posted show the same thing. The charges differed by a tenth of a grain but the average velocities were within a few FPS's of each other

 

[jugornot]

Now I think you are missing my point. For the most part weight SDs varied directly with Velocity SDs Which vary directly with group height. Well almost. Like I said good news all around. Using a dispenser with plus or minus .1 grain, is pretty close to having an expensive scale. For long range shooters there is a hint of hope that the tendencies shown for tighter groups. Not a great deal of difference, but a tendency that this small study (whose greatest fault is small sample size) hints at.

As far as nodes, I am much more particular than you. My ideal node is a spread that actually decreases across a .2 grain of powder. Invariably this also coincides with a small SD and ES. In most of my load tests it has been a -1 average for a .2 grain difference with low SDs.

But from there actual study:

6x47
SD charge 0.016 0.021 0.093 0.114 0.161
99% Plus 37.648 37.609 37.857 37.922 38.123
99%Minus 37.6 37.546 37.578 37.58 37.64
6.5CM
SD charge 0.02 0.016 0.076 0.055 0.147
99% Plus 42.242 42.212 42.426 42.301 42.671
99%Minus 42.122 42.116 41.97 41.971 41.789

Even better news The Harrel can vary plus or minus .45 grain and still give an average velocity very close to what the rest of the groups do.
In fact for the sd to represent what 99% of the shots will do you have to add +or- 3 SDs. Which are:

average charge 42.182 42.164 42.198 42.136 42.23


6x47 0.048 0.063 0.279 0.342 0.483


6.5CM + or - 0.06 0.048 0.228 0.165 0.441

Using the Harrel has 99% chance of being +or- .4 grains

Using the Auto charge has 99% chance of being +or- .25 grains

Using the Charge Master has 99% chance of being +or- .25 grains

Using the auto_trickler has a 99% chance of being +or- .055 grains

Using the Prometheus has a 99% chance of being +or- .054 grains

So using the extremes of the grain variances in reality 99% of the shots on :

Harrel .88 grains

Auto charger .5 grains

Charge Master .5 grains

Auto-trickler .111 Grains

Prometheus .108

Using avg velocity is useless. Single digit variances with very low SDs is my answer. But heck the harrel had low SD 1 time. That falls within the 99% realm. Not the average velocity but the SD seems to be a better predictor of group height. Once again the major failure of this test is a lack of samples. Good news with today's dispensers you can't measure to within .001 grains. The two best dispensers may get you within .05 grains. The dispensers that claimed to be +or- .1 grain are at least double that. And the Harrels would almost vary 1 grain.

What I do take away from this flawed study is the +or- averages for common dispensers is not what we think. +or- .02 grains is really more like +or- .05 and +or- .1 gram is more like +or- .25 grains. Now which do you choose to load to?

 

[hounddawg]

how many times do I need to repeat that I agree that SD has an effect on group height for it to sink in that I agree. How many times do I have to repeat you do not need to spend 800$ on a scale or measure to the milligram to get low SD's. I am getting as good if not better SD's as you are using regular old everyday scales, anyone can if they do load testing. You don't even need a chrono, shooters have been using ladder tests for years to find velocity nodes. The entire OCW system is based on it. I am sorry if that offends you so much but that says more about you than it does me. Wasting my time /ignored

 

[jugornot]

how many times do I need to repeat that I agree that SD has an effect on group height for it to sink in that I agree. How many times do I have to repeat you do not need to spend 800$ on a scale or measure to the milligram to get low SD's. I am getting as good if not better SD's as you are using regular old everyday scales, anyone can if they do load testing. You don't even need a chrono, shooters have been using ladder tests for years to find velocity nodes. The entire OCW system is based on it. I am sorry if that offends you so much but that says more about you than it does me. Wasting my time /ignored

Simple physics is all anyone need to know that lower SD's should mean lower vertical spreads Jugornaut. But what you cannot seem to grasp is that you don't need charges weighed to .001 grams to get low SD's. If you do your load development right you can use a Lee plastic dipper and still get low SD's

Deleted snarky comment. I apologise.

But I have a question, why all the references to SD? Accuracy and even the precision of the scale has little or nothing to do with SD so why not start a thread on SD and how it is achieved. I will be glad to post some chronograph records and we can see what makes a difference and what does not

Hmmm!

Truth here. I do have an Auto-trickler. It is a force restoration scale which is necessary for accurate trickling. See video1 and video2. The FX120i is accurate to supposedly .02 grains. Which from the video leads to grain variation from high to low of .05 grains. No where in my posts do I claim to measure anything to .001 grain.

You also use a scale accurate to .01 grains. First it is a load cell scale(see videos above) and all the scales for $20 on the internet Are not as accurate as you claim.

yep. My scales measure to .001 milligrams and .01 grains. Looks like the repeat ability is around plus or minus .002 grams and .01 grains. I like to develop my loads where I have a node where there is some leeway on either side and I also load to the distance I am shooting. I develop on the gram scale and am real picky about the charge. When I find a good node I just use the grain scale and call anything good that is plus or minus .02 grains for 300 and 600. At 800 I go back to being anal.

To bad you ignored me. Deny anything in this post.