If you are seeking a setting of 3.1gr then simply multiply that number times 10. Then dump 10 powder loads into your scale and adjust the dispenser until your scale reaches 31.0gr. Your powder drops will still have variations (3.10, 3.11, 3.09, 3.10, 3,10) but you'll have a much closer setting than you could ever get weighing single samples. Plus, most balance scales will have an easier time weighing 31.0gr versus something light like 3.1gr. Additionally, if you are low by 0.1gr on 31.0gr (30.9gr), then your average over 10 is still 3.09gr which is still close enough to 3.1gr for me!
I have tried it that way, but did not care for it. I am not sold on the measure being closer that way.
For loading on my LNL this is how I do it:
The
first thing I do is run
at least 10 or more charges through my measure to settle it down. I run primed sized cases through my LNL bumping the lever slightly at the bottom of every stroke. This is VERY important, especially with bulkier flake powders that settle a great deal. For non believers, test it out. Also keep the powder level above your baffle. If you don't have a baffle, get one. If you don't think a measure with 1" of powder in it doesn't throw a different weight that when it has 4" of powder in it, test this one too.
Then I set my scale on whatever weight I want. Say 5.4 Grs. I continue to run cases through my LNL, but now I pick out a case as it comes around. I weigh the charge. Lets say it is 5.2. I dial out my measures setting and run 3 or 4 cases through before picking out another one. I weigh this one. It's 5.3. I dial out my measures setting again. (Lets say 28.6) I run 3 or 4 cases through before picking out a case as it comes around and weigh it. 5.4 Grs! I am close. Now I run cases through weighing the contents of each one. I find that some are 5.4, but some are a bit less. (The pointer is a little below the 0 line) I dial my measure to 28.8. Again I run 3 or 4 cases through before picking out a case as it comes around and weigh it. I weigh it. 5.4 Grs. I am close. Now I run cases through weighing the contents of each one. I find that some are 5.4, but some are a bit more. (The pointer is a little above the 0 line). OK, I dial my measure to 28.7. Again I run 3 or 4 cases through before picking out a case as it comes around and weigh it. I weigh it. 5.4 Grs. I am close. Now I run cases through weighing the contents of each one. I do at least 7 or 8. I find that some are 5.4, some are a hair more. (The pointer is slightly above the 0 line), and some are a hair less. (The pointer is slightly below the 0 line). I continue to weigh some charges. If they continue to be at or slightly off 5.4 Grs in an even manner (over and under) I have my setting for that powder and that lot #. I record all these settings so I can reuse them. All I have to do then is check a couple of charges.
Obviously some powder meter better than others. Some are closer to dead on every time, and some are erratic enough to be difficult to get the setting. Some will throw dead on for 3 charges and then be off .1. AA #2 and True Blue are boringly consistent. They will throw exactly the same, over and over, with virtually no variance.
700X will barely do plus or minus .1 Gr, but works great for some loads. I just don't push max with it because I know it varies a bit.
As you can see I throw a lot of charges, after settling down the powder in the measure, and continuing to keep it uniform with the help of a baffle and a little consistent bump on every down stroke of the press.
I also size/deprime in a previous operation so I don't have the hardest part of the loading going on while I load. That helps keep the operation of the press more consistent when loading. It is very smooth without the stress of sizing and the priming action on the upstroke.
All these things help get more consistent powder weights. When I load, the press is being bumped just the same as when I get my powder weights.
Back to the main questions at hand.
I shoot the X-Treme bullets in .38 (light to standard loads) & .357 (light to midrange loads). If you stop at 75% or so of jacketed data you will be fine. It can be pushed a bit more actually, but 75% will keep beginners out of trouble.
I would work up .1 at a time with 700 X when you get past midway from the starting data to where you think you will stop. For a fast powder it is pretty forgiving, but it is still a very fast powder.
say 3.0grns to 3.1grns. It is very hard to tell the difference with such a small increment.
Yes, it can be. I covered that a bit in my powder weighing method.