A weight scatter array

[HammerMTB]

In Dale's thread close by (I'd say below but it might just rise above) he experimented with WW without tin.
I just experimented with WW and added tin.
I was curious how much my weight varied on the bullets. If I weigh 5, I get a small sample. I weighed 90 and arranged them in a scatter so I could visualize the variance and whether I might draw any conclusions from the time and effort spent. :idea:

http://i172.photobucket.com/albums/w15/HammerMTB/Boolits/DSCN1760.jpg

So, tho you can probably look at the pic and see most of this, the rows start heaviest at the top. I did not divide weights by tenths of a grain. If it was 264 grains, whether 264.9 or 264.0, it went in 264.
I have chosen 1% as a variance acceptable for my use. More variance might get a bigger pot of acceptable boolits, but really not much. 'Sides, it makes the math easy in my head [smilie=l:

There was only 1 boolit 265 gr, which is the advertised weight for the mold. S'OK, I know they vary depending on alloy.
As you can see, most of the boolits fall in the weight range of 264-261 gr.
However, there are a significant # of them in the 259, 258, and 257 rows. I know the print on the paper is hard to read, but there is a gap below 260 (row of 2 boolits). As I sorted, I thought I might have a mold throwing 2 boolit weights. But since there is a significant disparity in the # of boolits in the upper vs. the lower array, I don't think that is the answer.
Below the neat rows are about 20 that are light, from 255 gr on down. I even found one, all filled out, that is 220 gr! It has to have a void on the inside. I think I'll try to open it to see inside, somehow without destroying whatever void I might find in there, that is, best not use a hammer and chisel. :bigsmyl2:

[fredj338]

Are they all cast form the same alloy? With larger bullets, a 1% variation is pretty good. A 5gr diff. tells me there may be an internal void you can not see. I only weigh my serious competition or hunting bullets & any that vary more than 1% from the avg. get tossed back.

[runfiverun]

that's way too large of a range you got a .either your pot is cycling hot/cold. pot problem or your adding lead as you go.
those are linear from a cold to hot mold.
or you got two different mold cuts. [one hole is jacking you].
or you have poor casting technique.....sorry.

[Marlin Hunter]

Does the hardness go up with the lighter boolits?

are they all the same diameter?

Is your scale right or repeating properly? Try weighing every boolit in the same row several times. Air temp makes a difference on weight. The warmer the air or boolit, the lighter it will weigh. leaning on a table can also change the weight. What kind of scale are you using, electronic or mechanical?

[mike in co]

river run probably has it.
temp variation and height of lead in the pot will show up in weight variation.

mike in co

[HammerMTB]

that's way too large of a range you got a .either your pot is cycling hot/cold. pot problem or your adding lead as you go.
those are linear from a cold to hot mold.
or you got two different mold cuts. [one hole is jacking you].
or you have poor casting technique.....sorry.


I may try another run separating the 2 from the 2-cavity mold, just to see if that's it.
I do add, but I add sprues and rejects, not willy-nilly, but stopping maybe 1/2 way thru the run to put a lot back in, and waiting to get the melt back up to temp.
Hot/cold mold I guess is possible. In the past, that always showed up as wrinkly boolits. With the added tin, maybe it doesn't show as easily....

[geargnasher]

From the time my moulds first start throwing filled-out, shiney boolits to the full-frost boolits, there can be a loss of up to about 2-5 grains and .0005"-.001" in drive band diameter. I cull mine first by sheen, then by fillout/void issues, then by other defects and finally by weight.

I find that maintaining consistent mould and alloy temps = consistent boolit weights and sizes.

Another fly in the ointment is the annoying tendency of Lee mould sprueplates to warp, or stand off the blocks in one area causing some boolits to be longer than others. I just fixed a two-banger I had that had a 6-grain difference in boolits due to the sprue plate being warped, usually don't have this problem with steel moulds.

Gear

[HammerMTB]

Does the hardness go up with the lighter boolits?

are they all the same diameter?

Is your scale right or repeating properly? Try weighing every boolit in the same row several times. Air temp makes a difference on weight. The warmer the air or boolit, the lighter it will weigh. leaning on a table can also change the weight. What kind of scale are you using, electronic or mechanical?

I haven't hardness tested a lot of them, but could, esp as related to weight.
They are quite consistent in diameter, .432 and nice and round, too. Really couldn't ask for more there except they fall right thru my SRH cylinder. Not much I can do there, except not run them thru the sizer.

The scale is electronic. I did not reweigh a lot of them, but reweighed randomly as I went and got consistent #'s. I can cross check with a balance beam scale, too. They were all weighed at a single setting less than an hour long. Can't blame changing temp or other conditions, tho I don't see how that could reasonably affect the weight.

[qajaq59]

temp variation and height of lead in the pot will show up in weight variation. I believe you, but I'd be interested in why the temp would effect the weight? Does it causes voids?

[Bret4207]

6 banger and a bottom pour? If so you have compound problems. A 6 banger gives you 6 times the chance, (well, not really but you'll get the idea), for weight variation and a BP pot doesn't have a consistent head level so the pour varies. That's part of the reason I think a ladle makes better boolits. Add in the temp variations or sprue palte issues as the guys said and maybe some technique that needs polishing and there you have it.

[mike in co]

I believe you, but I'd be interested in why the temp would effect the weight? Does it causes voids?


temp relates to density, relates to boolit weight, height of alloy in pot relates to feed pressure from the pot (called net positive suction head is some engineering circles) affects how much alloy goes in the mold.

when volume casting i actually use two pots and alternate while the prior pot is refilled and returns to temp.


mike in co

[1Shirt]

The larger the number of cavs the higher the probability of increased variation. That said, I never have weighed handgun blts because of quantity fired, and the fact that I am never going to be a real decent handgun shooter anyway. I do weigh all of my rifle blts that I am going to fire for match or for accuracy testing. Have sometimes cut apart a couple that were very lite to find a bubble hole (for lack of better words). In general for 30's and above I am satisfied with 3/10's of a grain vairiance, but if I am shooting in a match, will go to exact weights. Less than 30, with emphasis on 22's and 6 mm's, I weigh and seperate to exact weight on an electronic scale. I do this after I have checked, sized, and lubed them. Ya, probably a bit anal, but so be it! I do believe strongly that consistancy in timing while casting has a great deal to say about consistancy of weight in blts dropped. I water drop every thing because I find it most convenient.:coffeecom
1Shirt!

[montana_charlie]

If you use a multi-cavity mould, it might be enlightening to keep bullets separate by cavity...then compare their weights within their own group. Then you are (essentially) analysing the output of a single-cavity mould.

I just checked a new batch of PP bullets from a (nominal) 550 grain single-cavity mould.
I culled 12 for visual defects.
Of the remainder, one weighed 545 grains, and two weighed 544.8 grains. They were desigated as 'foulers' for establishing barrel condition at the beginning of a (black powder) shooting session.

The 'keepers' broke down to 21 at 544.6 for one 'set' of loads sufficient for two 10-round groups...and 14 weighing 544.4 grains to provide for another 'set' to be fired into a different group.

My cheapie digital bullet scale only displays even numbers in the 'tenths' position, so I accept two-tenths of variation as close enough for my 'good' loads.

I don't do much 'plinking', but I'll accept half a grain on those.
CM