Lee Dipper 25% overload - ok experts?

mbsams

I have SR4759 and want to load 31.2 grains for my 45-70 Trapdoor and the Hornady 300gr. Hp per Hornady manual Vol 4. The slide rule dipper chart supplied with my Lee dipper kit shows to use dipper 3.10. I checked it with my Ohaus 505. The charge weighed 39.2 grains - a huge difference and an overload. I checked all the dippers and they all threw an average of 25% too heavy - the 4.5 dipper is more than 10 grains over. I have been using this lot of SR4759 for 10 years and my trusty Ohaus for all my reloading and the measured velocities are always what is expected. I checked the Ohas with known weights and it is correct. The only other powder I have on hand is UNIQUE. the dippers threw what the chart says and is confirmed correct with the Ohaus 505. The only conclusion I can come up with is that the chart for this powder is way off - aprox 25% too heavy - it's a good thing for me and my trapdoor that I checked the weight the dipper threw. I had to drop down to dipper 2.5 to throw 31.9 grains where the chart says it should only throw 25.2. Some variation is expected but not 25%. This is a very unsafe situation. Any possibility that this powder should be thrown by volume like black powder and not by weight?

XXCross

NO! Do not measure SR4759 by volume! You'd be in a world of hurt.

v35

I load for 17 calibers with Lee die sets and would never use any kind of measure not calibrated with a scale.
When you have time, check variation from dipper to dipper and you'll probably go out and buy a good measure.

sandwarrior

I never use the dipper. I always use a scale. Different powders have different density and therefore volume is not the correct way to measure powder. Only when volume is adjusted directly to a weight of THAT powder can you go by volume. Even then you give yourself some room.

jonk

Dippers are fine, but you must check from lot to lot and batch to batch with a scale. 4759 is a fine powder for the cartridge- just make sure you are using trapdoor data and not that for modern guns.

I wouldn't use jacketed bullets in the trapdoor anyhow, they're too hard on the soft steel bore.

heavyiron

Hi mbsams,

quote:Any possibility that this powder should be thrown by volume like black powder and not by weight?

Maybe I am not understanding your question correctly, but throwing the powder with a dipper is throwing by volume and the volume should equal something close to the correct weight as indicated in the Lee charts.

Differences in weight as measured by volume should not be as different as the 25% you have noted. The difference could be attributable to the bulk density (weight/volume) of the powder you are using changing over time.

The same type of gunpowders are known to vary from lot to lot both in burning rates, density, and other characteristics. For example, the Bulleye gunpowder made 50 years ago does not have the same properties as the Bullseye powder of today. You said your SR4759 was 10 years old. Could it be the Lee dipper is calibrated for a later lot of powder with a higher bulk density than your 10 year old powder?

My advice would be to weigh all your charges until your 10 year old batch is used up. You followed the correct reloading procedure to check a volume throw with a good scale. Keep up the good work!

I would also add that it is perfectly fine to measure gunpowder with a volumetric measure. In fact there is probably more powder measured volumetrically for reloading than by weighing because it is faster and easier. Every powder measure is a volumetric throwing device (similar to the dipper) but should be checked with a scale. That is how they were intended to work.

Heavyiron

scrubberguy

mbsams:
I have the Lee dippers and use the Lee dippers, However I never use the Lee dippers without double checking to see what they are actually throwing as far as charge weight is concerned!

Powder can and will change weight because of a varity of storage or moisture conditions so I always check each powder each time I use a dipper or scale!

This is reloading 101! Trust but verify!

Follow this rule and you will always be able to count to 10![8D]

varian

i started loading with a lee hand loader and dippers for the 45-70. each time i start to reload with any volumn power measure i weight 10 charges and use an average weight as my standard. never had a problem using this procedure. by the way, i really like 57 grains of 3031 for my marlin 1895.

rufe-snow

You sure that the 4759 your using is just 10 years old? Years back I use to use it for low pressure smokeless loads in BP cartridges. At one time the production of 4759 was stopped. Then a number of years later it came back on the market.

If I had to guess from your experience, either the lee dippers or your 4759 are out of whack. Either the dippers are set up for the older version of 4759, or your powder is the old stuff, before it was dropped by the manufacturer.

Call Lee about it tomorrow, I've spoken to there customer service folks in the past with good results.

CapnMidnight

I'm with Rufe, Lee has great customer serive people.
For what it's worth.
W.D.

tsr1965

The best thing to do is get yourself an adjustable powder measure if you already do not have one. You can use a scale to set it, and check for consistancy, and be done with it. No more need for dippers then...toss them, where they belong!

richbug

4759 was off the market for a number of years. When it came back it wasn't as fluffy as it used to be. Nothing wrong with your dippers, just IMR changed the powder.