i have lee turett with auto drum measure thinking of go to lee pro disk measure
? would i gain or lose efficiency.
I do mainly the same thing. When shooting competition, I used an RCBS uniflow measure to throw about 1/2 a grain light and then trickled up to exact weight on a balance beam. Now, I use a Lee dipper to measure out light loads and then use the dipper to trickle up to exact. This can be a surprisingly quick procedure when you get used to doing it.Sooo,... with all that bluster,... all I can say is,... I start charging cases by calibrating my balance beam scale with a Lyman weight check set,...FIRST,... BEFORE EVERY POWDER CHARGING SESSION! I then I UNDER measure out every charge within a fraction of a grain with a Lee Powder charger into a marlin444 case. Then, I pour that powder into the scale pan,... and then bring the weight up to what I want with a trickler.
I do this procedure with every case I charge,... every one!
loading large batches, auto druim varies from .5gr -1.0 gr this is checking every 10th rd.Need more information. Why would you switch to the LPDM? What do you mean by "gain or lose efficiency"? What kind of loading are you doing, large batches of a single load or small load development runs?
That is something you can easily test for yourself, you do not have to take anyone's word for it. Load ammo both ways and go shoot some groups. I mean I could tell you volume is more important than tiny weight variation, but you sound like you would not believe me anyway. FWIW, The benchrest guys throw their charges. I have not used a powder trickler in over 15 years. Empirical evidence is what it is and it does not lie. But do not take my word for it.I have had others tell me that normal powder variance of +/- .2 gr makes little difference in accuracy on rifle rounds. Not sure I buy into that.
I agree with Shooter444 in regards to the way I shoot rifle (read not high volume of rounds). 9mm and 45ACP on the other hand I drop them using a Lyman powder drop and stomp a bullet on top of them. I am not sure that the accuracy of those rounds effect my ability to hit an IDPA target at 7, 15 or 25 yards a whole lot. And trickle measuring 250-500 rounds of those is not what I consider a good time. My 327, I trickle those. Smaller case, so volume difference make a bigger difference and I generally am shooting 25 yards to 100 yards with that pistol.
I have had others tell me that normal powder variance of +/- .2 gr makes little difference in accuracy on rifle rounds. Not sure I buy into that.
I have a sticky you should read, about using a volume device as intended.loading large batches, auto druim varies from .5gr -1.0 gr this is checking every 10th rd.
am wondering if the pro disk is closer than that.
Then you just aren't old enough. 😉 It didn't used to be uncommon to see volume info. But as you know, most volume based devices aren't actually a stated volume measurement; Simply dashes or arbitrary numbers. Whereas just about everyone since the roman empire has had access to accurate and inexpensive scales.I also know that I have never seen a loading manual say to load your 30-06 with 2.83CC of anything. I use Lee dippers and powder drops. I believe both vary more in volume on some powders a lot more than my beam scale will vary. I don't intend to test that for myself and present the data either.
If a 0.1 grain variation in charge weight had a substantial effect on group size, then odds are that you need to work up your load again. It clearly isn't hitting an 'accuracy node' if it is that sensitive. Worse, any variation in local conditions (temp, humidity, air pressure) are likely to make groups go down the tube.Yah, I don't buy that either!
I have seen POI open up, and tighten up, with a just .10 variation in weight.
👆This is why I asked, you are confusing some things.1) The other issue is, it could measure the volume, tap it on the bench and measure it again and shake it up and measure it a third time and most likely get 3 different volumes.
2) From experience and discussions, I have never really though as volume of any powder as being fixed.
3) But if I was really going to get down to the biggest reason I trust weight compared to volume. I can use a check weight or zero my scale. I don't have a way I trust to verify volume, other than to weigh it.
4) To get somewhat scientifical, powder burning is a chemical reaction. Density of powder can change as noted above. The mass of the material has a much closer relationship to how much material is available for the reaction and for all intents and purposes is fixed for a given 1 or 8 lb can of powder. I do not remember any calculations off the top of my head for any change of state of a material that uses volume for the amount of material being reacted (it has been a long time for in depth chemistry).