Auto disc measurements


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J_McLeod
November 1, 2011, 02:51 AM
I finally got around to loading some 95gr TMJs tonight that I got from RMR last month. After setting up the turret and auto disk and dispensing several charges to get the powder cycled through I decided to check the weight before loading. First I tried the .46 disk which should have given me 5.0gr of HP-38 but instead it weighed at 4.5gr along with the next 5 charges. So I put in the .49 disk and got 5.0 instead of the 5.3 I should have gotten.

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16in50calNavalRifle
November 1, 2011, 03:32 AM
Note that I've only been doing this for a few weeks, but I always weigh what a given disk is dispensing at the time I'm actually going to reload (and check charge weights ever 10-15 rounds anyway as part of quality assurance). Lee says and common sense agrees that things like temperature and relative humidity will vary and this will change the amount dispensed by a given disk. Also different lots of the same powder may vary in the way they meter through a powder dispenser.

I glance at the Lee table for "ball park" data on which disk to try for a starting charge, but after that it's trial and error, moving up one disk or disk cavity at a time - and already I am working more from my notes than anything else. But each time checking what that day's results will be before I start reloading.

HP-38 meters well in the Auto Disk. Your "error" of .3 grains on that one disk sounds typical. If you really really want a specific charge and that amount is "straddled" by two consecutive disk cavities, consider the Adjustable Charge Bar (for charges of 3 grains and up). There's also the disk-stacking option, an extra you can buy from Lee. Or modify one of the cavities by partially filling it with something (there are posters on this forum who modify their disks this way - that way you can have a dedicated disk or cavity for a specific favorite charge - search this forum for details).

bds
November 1, 2011, 03:33 AM
Update, 16in50calNavalRifle posted while I typed.

+1. That's typical. Use the Auto Disk chart more as a guide as there are lot #/production year variations that will vary the actual powder drops by .1-.2 gr. What's more important than whether the chart is accurate is the consistency of powder weight charge-to-charge. Most of my Auto Disk drops with W231/HP-38 (once the powder has settled after 3-4 cycles) are accurate to .1 gr charge-to-charge.

For me using Ohaus 10-10, .40 hole will drop 4.2 gr, .43 hole will drop 4.5 gr, .46 hole will drop 4.8 gr and .49 hole will drop 5.2 gr for both W231/HP-38.

J_McLeod
November 1, 2011, 03:37 AM
I have an adjustable, and have used it a lot. Tonight's measurements surprised me because it's been +/- .1 every time I've used it with HS-6.

bds
November 1, 2011, 03:40 AM
When I use the adjustable charge bar, I always verify the powder drops with the scale.

jcwit
November 1, 2011, 06:46 AM
Remember the mfg. always errors on the side of the lawyers.

brl0301
November 1, 2011, 06:57 AM
^ +1 ^

I always just use the lee info as a starting point and always use a scale to verify the actual weight of the powder

fpgt72
November 1, 2011, 09:47 AM
Yup same with me....it just gives you a starting point to work from. I also use their perfect powder measure and it is the same way....just figure out a ball park and go from there.

squarles67
November 1, 2011, 10:49 AM
HP-38 always weighs lower than the chart reads for me also. I've found some powders come out right on and some measure low but I've yet to see one throw more than the chart says.

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