Rejecting by weight variation ?

[BigSlick]

Hi guys,

I cast about a hundred .501-440 Lee bullets tonight for the 500.

Still trying to get some useable experience under my belt. I added a bit of tin to aid fill out, which worked great.

In my attempt to keep moving at a steady pace, I dropped a couple of pours when I didn't have to mould closed 100%. I know, it's a screw up. I got a little lead on the alignment pin on one mould half and ended up getting a little fin on the bullets cast before I caught it.

Otherwise a good session - I think.

After weighing all the bullets, I dropped a range in weight of 439.9 - 442.1 for all but the ones with a fin, which I will attempt to trim and weigh. The bullets with a bit of fin all weighed in the 448-454gr range. All but one filled out nicely with sharp grooves and bases. I'm pretty sure it was from the first drop.

When culling bullets, what range of weight do you consider acceptable. I was kinda thinking 1% variation would be OK but that seems like a lot ~ 4gr overall with these bullets.

Thanks for the feedback ;)

'Slick
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[cohutt]

Hi guys,

. I got a little lead on the alignment pin on one mould half and ended up getting a little fin on the bullets cast before I caught it.


'Slick

Slick I wondered where you've been lately now i know. I did this too, ended up with a dozen or so "mohawk" bullets.... i tossed- the fins popped off easy enough but the bullet was obviously not true round- still ridged sort of.

Good question- I am curious what experienced casters feel is an acceptable "cull" rate in a session. 2%? 5%? 10%? Also, I decided to cull the first couple of pours in a session and write them off as mold-heaters, send them back into the pot. It seems my first ones out of the molds have not been as good as the ones produced in the "groove" of the session once up and running.

[rmb721]

I would say it depends what you are going to use them for. No need to weigh if they are for plinking loads. If they look OK, good enough. For benchrest loads, you would probably want them in batches within 1/10th of a grain. It all depends on what suits you.

[BigSlick]

I ran these at 800 degrees according to my RCBS thermometer and let the mold sit on top of the pot for a while to get good and hot.

I didn't drop the first bullet until I was right at 800 deg, so I *think* my molds were hot enough. maybe not.

I dropped a few 93gr Lee .32's early this afternoon too. They were all within 1 grain, weighing in at 98.2-99.0 gr. About two dozen wrinkled bullets, then I cranked to pot up to max and waited. Things got better with the additional heat.

The 440's are some honkers. I'm jonesin to shoot them thru the beast, but gotta let the range dry out some first. I figured I would immerse myself in minutia while I'm waiting.
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[cohutt]

The 440's are some honkers. I'm jonesin to shoot them thru the beast, but gotta let the range dry out some first.

Those would leave a rut like a plane crashing into a wet range- real strip miners

I let my molds sit on the pot too but still have this thing in my brain that a little heat from the inside brings the whole mold up to temp.... maybe my first pours suck for other reasons; I create a long list of possible causes just by plugging in the pot/

[454PB]

You're doing great to keep a 440 grain boolit within 3 grains!

I've wasted a lot of hours weight sorting boolits, only to find that a good visual inspection is just as good.

Each of us has our own standards, so we cull boolits differently. I cull the real obviously bad ones as I'm casting, the rest get a thorough inspection before sizing. WAG....I reject about 5% of my castings.

[John Boy]

Slick ... just some suggestions:
... Use the Eight Phase Casting Cycle: http://www.longrangebpcr.com/8Phases.htm to keep the bullets in the tight bell curve grain range (make sure to weigh them when they are cold)
... Clean the mold vent lines with a razor blade, keep the pins lubed and the mold halves should close properly to eliminate the fines
... At 800F, would think the bullets are on the frosted side. Run the pot down to the 720 - 730F range and try to hold the temperature within a 10 degree variation.

My Lyman 457124 for example, (385gr - 1:20) mold casts shiny, fully filled out bullets with a nice bell curve weight variance at 710F. I hold the temperature range using a digital thermometer and will never look back using a bi metal

Because I shoot a lot of long range BPCR, I sort the bullets into batches that are a 0.5gr range. There will be some that are outside the majority of the bell curve ... they go into the pot and get melted down into an ingot for the next session

[David R]

Good question.

I have found with some guns, I can cut group size in half by keeping to .5 grains, but most I just shoot.

My 22-250 is the best example, I pour 55 grian 225464 boolits out of pure linotype. If I weigh them, it will cut groups in half. This isn't even noticible until I get out past 100 yards.

55 grain booit by .5 grains = almost 1%.

30 cal, I keep to + or - 1 grain. ONLY for target work. Anything else it doesn't matter.

David

[44man]

I have to agree with what the guys said, it depends on the use of the boolit. For benchrest or long range BPCR shooting you want close tolerances. I quit weighing boolits long ago by using the proper casting techniques. By pre-heating the mold to 500 degrees in my little mold oven, the first boolit is perfect and by working right I might have one reject per 100, sometimes none.
There are three secrets to good casting, don't cast sloppy with lead all over the mold and inside it, even temp on the lead, even temp on the mold.
The smaller the boolit, the closer you want the weight and the tighter you want the variation. On those big sodbusters, it just doesn't matter much. Your biggest worry with sloppy casting is a size variation because of the blocks not closing the same. Of course, that also throws off the weight.
If you want a laugh, you should watch my friend cast. The whole top of the pot, bench, floor, his shoes and the entire mold gets splashed with lead. The floor looks like a radiator shop. I have never seen him pour a decent boolit but he shoots good. I have shown him over and over, but he loses it. To tell the truth, none of my friends can cast even if I hold and guide their hands. As soon as I let go, the slop starts again.

[9.3X62AL]

No argument at all with the comments posted above. Slick--yer doin' fine!

For most handgunning, a 1% variability is fine, as long as the boolits are visibly consistent. Those two factors seem to run together much of the time, once everything gets heated up and running well. Anything "finned" gets tossed back into the pot. My first several casts get recycled, too. Rifle boolits for precision or long-range work likely need weight-sorting and closer weights, esp. small caliber rifles (under 30 caliber). Weight-sorting is like case trimming to me, and if it isn't needed--I dont do it.

I run my pot at around 675* with 92/6/2 alloy or wheelweight alloy. I noted in both iron/steel and aluminum molds that I gained between .0005" and .0015" in diameter by running the metal cooler.

[Junior1942]

I visual sort first, then I sort by 1 SD for target shooting or by 2 SD for plain ol' shooting. A digital scale is handy for sorting.

[fourarmed]

I normally sort by appearance only, but last weekend (snowed in) I was loading for my silhouette revolver, a DW .41 mag. I decided to go whole-hog (or at least 3/4 hog). I cleaned primer pockets, trimmed, and annealed the cases. I was loading 410459 boolits that had been visually inspected at the time I sized and lubed them. I used a digital scale, and weighed 225 of them. I decided to sort them into 3 groups: under 217gr., 217-219 gr., and over 219 gr. My goal was mainly to eliminate the really discrepant ones, if present. I wound up with about 20 boolits each in the over- and under- categories. Only one boolit was more than 1 grain outside the central category. I had one that weighed 215.5.

[cbrick]

The easiest way to get (or reduce) weight variation is mould temp variation and alloy temp variation. I pre-heat the mould and then don't even look at the bullets from the first 8-10 fills, they will be the lightest bullets in the casting session. LAH nailed it in another thread when he said: Casting = time and temperature. Keep your alloy temp constant and cast at a steady, even pace to keep your mould temp constant and you will greatly reduce weight variation.

If your going to weigh your bullets the amount of variation that is acceptable depends entirely on the intended use of the bullets. I don't weigh my bullets even for long range revolver accuracy testing. I do weigh about 8-10 bullets from each casting session as a means of checking for any alloy variation from previous casting sessions with that bullet. If your going to weigh them, determine a percentage of the whole, a 2 grain variation in a 55 gr bullet is far more variation than a 3 gr spread (+- 1.5 gr) in a 250 gr bullet.

In long range revolver group testing (150 and 200 meters scoped from bench) I have found that alloy BHN variations will effect groups more than minor weight variations. My 357 FA revolver likes the BHN at 17-18. If I go harder (all the way up to 30 BHN) I loose velocity though groups are still fairly good. If I go softer I loose both groups and velocity. If use a BHN spread of 15 to 25 in the same group its lucky to even hit the 150 meter target. I don't get that kind of difference from bullet weight variation so I don't weigh the bullets.

Rick

[BigSlick]

Thanks for the feedback guys.

I tossed all the bullets with fins back in the pot and used them and a few ingots to drop a couple of hundred .401 175 TC bullets.

All of these have weighed in with less than 1 grain variance, with most being less than ? grain. With the alloy I'm using and my moulds weight was 180.9-181.8gr

I read thru the 8 steps info John Boy posted. It made sense, so I tried to keep my timing for each step the same. I had to stop twice, once for the BBT with my Lars Red and once for a pit stop. I kept the mould on a hot plate while I was away from the pot.

I ran my temp down to the 700* range. The bullets are all shiny and smooth except the ones I dropped when I took the breaks. Those were frosted but still good (turned out to be the lightest of the bunch).

I am going to lube as many as i can over the next couple of days and hit the range Monday to see how these shoot before pouring any more.

Any of you happen to have a consistent measurement in inches of how much tin to add for a 17lb load of ww's ? I weighed the 2% I added yesterday and today, but was in a hurry to get everything set up and didn't measure it by length. 17lbs (if I got the numbers right) will take about 1/3 lb to make 2%. I'm using 95/5.

Thanks for the info and the PM's. You guys are gonna make me think I can do this if these bullets group any better than minute of the broad side of a barn.
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[cbrick]

Thanks for the feedback guys.

Any of you happen to have a consistent measurement in inches of how much tin to add for a 17lb load of ww's ? I weighed the 2% I added yesterday and today, but was in a hurry to get everything set up and didn't measure it by length. 17lbs (if I got the numbers right) will take about 1/3 lb to make 2%. I'm using 95/5.

I use an electronic postal scale to weigh the ingot, then use a calculator to determine the weight of the tin in the percentage I wish to add.

Rick

[Dale53]

2% of 17.0 lbs is 5.44 ounces. This is easy to calculate with a calculator and then just "melt in" 5.5 ounces (that is close enough).

Dale53