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Discussion Starter · #1 ·
I just got a new 600Jr for the .410 bore. It came with bushings number 10, 11, and 12. The Lyman's 4th edition says these bushings should throw 13, 13.8, and 14.6 grains of H110 respectively. The Mec site says they throw 14.2, 15, and 15.8 grains. Am I missing something? I'm currently weighing shot and powder on a scale, but when I find loads I want to produce in quantity I'll want to fill the shot and powder bottles (and buy more bushings). Anyone know why there is such a difference in the two figures? Could I be misreading the charts?
 

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HuntNshoot said:
Could I be misreading the charts?
No, you're misunderstanding the charts.

They're only guides to get you in the ballpark of which bushing to use. And not only do they occasionally vary, as you've seen, but usually any given bushing won't actually drop what the chart says it will.

The bushing selection sequence goes like this:

1. Pick the load recipe you want from a powder company's printed load guide or website based on your desired hull, shot weight, velocity, powder weight, primer and wad.

2. From the bushing chart, select the one nearest your desired powder weight, put it in the press and drop some charges, weighing each one and returning the powder and shot to the hoppers each time.

Drop three or four to get the powder stabilized in the bottle, then drop about six, weigh and write down the weights, then add them all and divide by the number of drops to get the average.

If that's close enough to the charge weight you want, then that's the bushing to use. Otherwise, get the next larger or smaller bushing and start over with the testing.

Do that until you find a bushing that actually drops what you want.

If a bushing drops within a half-grain or so more or less of your desired charge it will be okay if you can't find a bushing that gets any closer.

Leave that bushing in the press and use it from then on for that powder weight. It's not likely H110 will vary significantly from lot to lot.
 

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Lyman's #4 was published some 11 years ago, and the data was no doubt collected over some period of time prior to that. The point is that things can change over time. I doubt if Lyman's staff went through the trouble of checking each bushing they show in the manual, so they no doubt took what the manufacturer sent them. Printing error? Bushing diameter change? Who knows?

Follow Case's recommendation. For whatever it might be worth, my #11 bushing drops 14.5 grs. H-110 from a Sizemaster.
 

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Discussion Starter · #4 ·
Thanks guys. I was a bit worried since one set of values was nearly a 10% difference. Guess I'm still in "metallic" mode.
 
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