weight variance in cast bullets

[robertsm53]

I'm not new to casting and know that a number of variables will affect the final weight of cast slugs. The question I have for you folks is, for accuracy how big a variance in weight is ok? I have begun to weigh each bullet, and separating them by weight. This is not rocket science and although time consuming it is a simple process. . The slug I have started with is a Lyman 250 grain slug, .380 Dia. to be shot in a 38/55 Sharps. The vast majority are coming in at 250 Grs. to 253 Grs. Bullets outside this range are discarded and those remaining are separated by weight. The first test batch are all + or - .5 grs. 249.6 to 250.5 go in the 250 gr batch, 250.6 to 251.5 goes in the 251 pile. Does that allowable variance seem to big? Would a tighter allowance really be worth the effort? I can break them down to +/- 1 or 2 tenths of a grain but would it be worth the effort? Another thought would be to settle on a given percentage of the bullet weight. I don't know, maybe plus or minus 2% of bullet weight?? I will also be weighing and separating slugs for .30 caliber and both 45/70 and 45/90 rifles. In the past most all my casting has been for Cowboy Action shooting where "Minuet of Cowboy" at a few feet was all that mattered.

[leadhead 500]

A good way to sort is to sort and keep what’s within 1%.

[charlie b]

When I looked at weighing bullets I decided to check what the good jacketed bullets were like. .30cal. Sierra 168 Match Kings had a 0.3gn spread. Hornady 168AMax were 0.6gn spread. Both bullets shoot to 0.5MOA in my rifle.

So, when I weight sort bullets they are in 0.5gn spreads. I usually shoot 210gn bullets in my .308. MOA accuracy out to 300yd.

The other thing I look at is a minimum weight. Seems that below a certain weight I get larger groups and/or more flyers. For me that means the bullets must weigh between 209.0 and 211.0

PS when I really want to shoot for minimum group I will use bullets of one weight, eg, 210.5gn.

[quilbilly]

1.5% works for me on either side of average for 100 yards or less but beyond 200 yards, 1%.

[Rcmaveric]

If I feel a need to weigh sort i go with the 1% extreme spreads.

That applies to cases and bullets if I weigh sort them.

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[gnappi]

Wow! I have mainly only cast for handguns at most handgun distances as well as my TC's / XP-100 at ranges up to 100 yards and as handguns go have been satisfied without sorting.

Are you all seeing results as good as Charlieb? What ranges, calbers and accuracy improvement are you seeing to be worth the sorting? Maybe I'll consider this for my 200 yard .308 plinker

[Rcmaveric]

Depends on what I am doing. Sorting bullets won't turn an 2MOA group into bugeyes. But it will shave .1 or .2 off a nice group. So if you are shooting where .1 or .2 off your group is the difference between a win or loose the. Do it.

I sort bullets for 200 yard shots and over.

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[robg]

once i start casting i dont flux again till i refill pot , get less weight variation.

[charlie b]

Depends on what I am doing. Sorting bullets won't turn an 2MOA group into bugeyes. But it will shave .1 or .2 off a nice group. So if you are shooting where .1 or .2 off your group is the difference between a win or loose the. Do it.

I sort bullets for 200 yard shots and over.

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Not into bugeyes, but, I go from 2MOA to 1MOA by careful sorting.

[robertsm53]

Thanks for the responses guys.
This morning I cast up a small pile of .458 / 405 Gr. bullets and just got done weighing them. As expected they all came in heavier than the stated 405 grs, from 418 to 425 grains. The ones the fringes I tossed back in the re melt pile, and kept the bullets that were in the 420.0 to the 424.9 range. I only had 3 that were 425.0+range, and 9 that were less than 420.0 Grs. Wound up with 115 bullets that were in 420 to 424.9 range. I was bottom pouring from an RCBS Pro Melt II set at 775 degrees. Tried to cast set at 770 but it was a bit to cold and would not fill out the mold completely. I don't know what the real temperature was, didn't have my laser thermometer handy. next time I will double check the temp setting against the Thermometer.
I have the equipment and tools to ladle cast, and do plan on trying that method eventually as well.
These were weighed PRIOR to putting the gas check and lube. As I run them through the sizer die and reload process I will keep them in sequence and fire them lightest to heaviest to see how they group. My local range is only 100 yards, so I don't really expect to see any real difference but I do want to get in the habit and see the results when I get to the range where I can get out to 1000 yards. These bullets will do for shorter distances, and I have had some success out to 5 or 600 yards. After that I will be following the same procedure with a couple of 500 + grain molds.

[sharps4590]

Ladle casting and using the same alloy, once melt and mold are up to temp and that temperature is maintained, 90% to 95% of the bullets will weigh within one grain and usually there is one weight that is predominate, such as 264.8 for my 9.3 bullets. I usually sort into 1 grain weight difference and load them as a batch. I don't know if that's necessary or if they shoot any better but I feel better.

[fa38]

When I sort I usually keep the real low weight bullets for warming the barrel by shooting into the berm. No sense in shooting a match bullet into the berm. I take a red sharpie and mark the nose of the bullet to indicate the bullets I shoot into the berm.

[PAndy]

I buy bast bullets. My best sources get about 3/4 of the bullets +/- 0.5 gr from average. I don't know how they do it. Some commercial stuff will have some bullets ranging +2% to minus 2%. Honestly those shoot pretty well unsorted .

[robertsm53]

Just cast another batch of the RCBS 405 Gr. 458 Dia. bullets today, and Thank you Sharps4590. This batch dropped out of the mold a lot easier, and just about 1.5 Grs. heavier, with less variance between each slug. I weighed each one on my Dillon Electric scale to the .10 of a grain just to check them out and they were closer in weight. The first dozen or so were still a bit cold until the mold came up to temp, and they were well below the norm. As I looked at them I could see that the lube grooves were not well formed and the edges and step for the gas check were rounded as well.

fa38 Thanks for the warming the barrel input as well. I will use those at the local range, at only 100 yards they will be my "Plinkin" shots. Also there seems to always be someone around who would love to shoot the old buffalo guns, and these would be great for others to shoot just to say they got to shoot a Sharps.

I use empty .45 ACP plastic bullet trays that get tossed in the trash an my local range to line up the bullets and keep them in order as I weigh them, works like a charm. After I run them through the RCBS LAM II, I place each slug in the plastic tray, with another inverted over them, tape the trays together and label the outside as to contents. Bullets stay clean and gas checks don't get knocked loose, Lube stays put and they are ready to go days or months later. Next up is the 530 grain slugs, and the fun continues!
Thanks all for the ideas and suggestions