Lee Rifle mold consistency??

[BobinIL]

Is it me or is it the nature of Lee molds?? I cast a batch of bullets with my 2 cavity 457-340 and 457-405 molds and I find the bullet weights vary by 1 to 1.5 grains. Usually I end up with 2 separate groups of bullets of 2 different weights with a few outlyers. I assume this is due to the 2 cavities being inconsistant. I love lee molds for pistol bullets but if I am casting precision long range rifle bullets perhaps I should have bought Lyman or RCBS single cavities. I usually weigh my rifle bullets and try to keep them + or - 0.5 grns. With these molds I am rejecting 70% to 75%

[mooman76]

Many things affect the consistancy of the mould and it is probably the way you are casting. On a better note I think you are being too critical. On a 405gr mould if you are off by 1 gr you are off by 1/4 of 1%. That's not bad at all.

[Dale53]

Offtimes, Lee two cavity moulds don't close the same each time. The alignment surfaces are aluminum to steel. This metal combination and design tends to "gall". So, if the mould closes correctly one time and not perfectly aligned the second time, the bullets WILL vary in size.

The solution is to lube the alignment surfaces with Bullshop's Sprue Plate lube. This is no BS, it DOES make a difference.

http://bullshop.gunloads.com/tbs_lube.htm

FWIW
Dale53

[Mk42gunner]

You could figure which cavity casts the boolit you like and run the mold as a single cavity. Like mooman said you're off less than 1/2 of one percent even on the 340 grain boolit.


Robert

[qajaq59]

On the Lee you have to be a little more careful how you close the molds. They can have a bit more slop then the Lyman does. I have several sets of Lyman molds as well as Lees, and one of the lyman's is off a bit too. But it seems to have no effect on the shooting. And if I'm working up a load, and being picky, I weigh and sort them anyway.

[runfiverun]

the amazing thing here is that you are able to keep your weight tolerances that close with lee molds.
even custom molds in single cavity using a mold lock and timing each movement will only get you so close.
like said above 1/4 of 1% is outstanding..
i get a tenth of a grain difference in lube weights sometimes.

[AZ-Stew]

mk42 and runfive are on track with this one. A whole bucket full of other things related to your shooting are going to have to be absolutely perfect for you to be able to tell the difference on target caused by a fraction of a percent difference in boolit weight.

Regards,

Stew

[Recluse]

the amazing thing here is that you are able to keep your weight tolerances that close with lee molds.
even custom molds in single cavity using a mold lock and timing each movement will only get you so close.
like said above 1/4 of 1% is outstanding..
i get a tenth of a grain difference in lube weights sometimes.

+1

And I was going to ask if this size/weight difference was before or after sizing and lubing?

[rhead]

the amazing thing here is that you are able to keep your weight tolerances that close with lee molds.
even custom molds in single cavity using a mold lock and timing each movement will only get you so close.
like said above 1/4 of 1% is outstanding..
i get a tenth of a grain difference in lube weights sometimes.

runfiverunn is right on.


I would say that that is quite good with any mold from any manufacture. You are obviously doing many things right.

What level of precision do you normally get from your non Lee molds?

[delt167502]

I use the 405 gr.and the 340 gr. only mine are lyman,they will very as much as 3 gr + - . If you are shooting at 300 500 yards it might make a diff. I tried varying the lead aloys to get diff. wgts. as much as 5 grs.+- . Loaded same 405 gr (20 rds) fired at 200 yds. 4 groups of 5 largest group of the 4 was 3". I then sorted and loaded (20 rds) that were within 1/10gr. fired 4 groups of 5 the largest group measured 2' 7/8".unless you shoot long range,I can't tell a diff. the smallest group measured 1 1/8" which is better than I am.