Cast boolits: Acceptable tolerances?

[Jumping Frog]

I have some question about what kind of quality control I should exert over pistol bullets I recently cast (ingots were from wheelweights).

As my first cast session, I produced about 1200 .40 S&W bullets. The mold is listed as 175 gr. nominal weight. These are not for precision target shooting, they will be for USPSA/IDPA type shooting (and practice) typically closer than 25 yards.

The bullets were sorted in weight categories.

172 gr = 23%
174 gr = 45%
176 gr = 22%
178 gr = 10%
Outliers 170 and less, or 180 and higher = 1% (back in the melting pot)

So I have two questions. First, is this amount of variation typical, or will my tolerances get better as my technique gets better?

Second, would you keep the lots segregated when I load them, and then shoot them in similar weight batches? For example, only shoot 174's in a match? Load the 172/174's to one powder weight and the 176/178's to a different powder charge? Figure these are close enough and lump them all together? What? How close do the weights need to be, or is this amount of variation meaningless?

I am kind of like the dog that chased a car. I caught it and now am unsure what to do with it.

[randyrat]

I'm quessing it's your mold,alloy heat+ rythem. Once you get them consistant you will throw boolits more consistant. +/- 1 =1-2 grains, sometimes less
I would try the 2 extreeme sizes and see if they make a difference in your weapon/load for accuracy at the distance you need.
You have to be the judge.

Some of those boolits were made with a cooler mold/alloy some were made with a hotter mold,faster,slower,hotter alloy, you got the idea....

[Bret4207]

I'm guessing you're using a 6 banger? Here's what I'd look for- take your 2 heavier groups and see if you can determine why they are heavier. I'm thinking you may have been getting better fill out. See if the lighter groups have incomplete bands or bases. A 6 grain spread in a 175 gr boolit is significant, but not unusable. See if you can determine of some cavities throw heavier than others. That can happen and casue you no end of frustration. Did you stir the pot at all during your casting session? Add ingots? Did anything change during the run? BP or ladle? Did you change hands or the height you poured at?

Casting is as much an art as a science. You casting rhythm and style can make a huge change in how your boolits turn out. For me casting fast with a hot mould works, other guys cast slower or use a BP or other different styles. You need to find what gives you the most consistent results and go from there.

[Wayne Smith]

If a six cavity I'd guess one cavity throwing heavy. If you can identify it and use it as a five cavity the remaining 4gr variance shouldn't affect the way your are using them. 6gr may not. I'd load them and shoot them and see how much high the heavier boolits shoot. You may be able to use them as they are. You are not shooting for small groups, after all.

[Dale53]

Using a multi-cavity mould:

First cast until you are getting consistent quality. Then, when you have a really good mould full, carefully empty the mould to the side and save all of the bullets from the mould. You can then weigh and measure each separate bullet. You might want to do this a couple of times. That way, you'll be certain if the variance is caused by different mould cavities or something else.

Holding the mould tighter or looser can cause the bullet to vary slightly in diameter (it is hard to measure but easy to weigh). Just a few tenths of a thousandth differences will show up on the scale.

Cabine Tree actually makes a clamping set of mould handles that guarantees that the handles will be held at the same pressure for precision cast bullets. In fact, I use one on my single cavity custom mould for my schuetzen bullets. I cast those plus or minus .2 of a grain (two tenths of a grain). Those bullets will shoot in half a minute. A nationally known shooter friend of mine throws any bullet back that isn't SPOT ON. He has set record groups with his plain base lead bullet rifle at 200 yards (groups just over and under .7 of an inch!).

My pistol bullets are cast to +or- .6 grain. It usually runs closer. I use multi-cavity moulds and the makers did a FINE job on mine. The cavities are VERY close to each other. I cast large bullets (40/65 and 45/90) to plus or minus .6 of a grain.

If you have several grains difference between bullets you need to find out why (mould or technique) then make suitable corrections.

Dale53

[Hickory]

I use to have the same problem until an old time caster helped me out with it.
When dealing with W-W they all end up in the same place (5 gallon bucket)
However, they come off of different cars that have been rewheeled from
different tire centers. These tire centers buy their W-W from many different sources.
Most people with a bucket of W-W will melt out of the bucket as they need more boolits.
the solution is to melt down the W-W in as large batch as possible, stirring and adding alloy as needed.
At this point I cast a few boolits and check the the hardness. 15-16 BHN seem to be about right for me.
I then pour the melted lead into ingots.and mark them as a batch for future use.
This has helped me to keep the weight of the boolits from fluxuating.

[Jumping Frog]

My pistol bullets are cast to +or- .6 grain.

Well, you have all keyed on some very important issues. Being my first casting session, I see I was not particularly consistent. Thanks for letting me know that ranges from 171 to 179 grains are too high. +/- 0.6 grains appeals to the engineer side of me.

Yes, as you guessed, I am using a Lee 6 cavity mold. Next time I cast, I will need to investigate the weight from each cavity.

What do you think I should do with the boolits I've got? Shoot them off and try for better next time?

[ChuckS1]

Check the bases to make sure they're flat and corners are square; that's where your accuracy lies. I wouldn't worry about the weight variance due to the range and the level of accuracy you need for USPSA/IDPA type shooting. If anything, what's makes a difference might be making sure the bases are square. I shoot conventional bullseye using .45 ACP H&G 68 200 grain SWC boolits. At 25 yards, except with flawed bases, my less than perfect boolits still group in the 10 ring. But at 50 yards, I triple check those boolits to make sure they're as good as possible. If I were to rank the top 5 factors impacting accuracy with cast boolits for the type of shooting you're describing they would be (in this order):
1. Shooter
2. Shooter
3. Shooter
4. Shooter
5. Cartridge

It's the fundamentals of marksmanship that make the difference. I've seen plenty of guys without high end guns and ammunition win matches based on marksmanship alone. USPA might be different in terms of the race guns, but I can guarantee you that every one of the winners are expert marksmen.

[runfiverun]

in the type of shooting you do if they will hold the a zone or tip a plate they are good enough.
but i would investigate the out of spec thing.
if it is one hole so be it, just don't use it.
if it is something else like adding cold metal to your pot and changing the alloy temp for 5-6 pours that is something you can control, and should ,just cause it's the way to go.
accuracy starts with the boolit.
and if you are questioning it it won't help your shooting,confidence is a very big part of shooting.
if you are sure of your ammo,you are sure of your shooting.

[Dale53]

A number of years ago, several of us at our gun club started shooting PPC. PPC is not terribly demanding of ammunition but it CAN be demanding of the shooter if the competition is serious. I live in an area that has some serious competitors of all disciplines living and shooting.

We all progressed from not so good to pretty dern good. We started to sort out those who were not terribly serious from the seriously good shooters. One of my shooting buddies worked very hard and he seemed to have the necessary eye/hand coordination to do well. When some of us started to pull ahead of him (I'm talking serious differences here) he became VERY frustrated.

I put his gun on the Ransom Rest and it was shooting about six inches at 25 yards. My gun had just been run and it was shooting 3/4" groups at 25 yards. I had a suspicion as to what was happening. After I ran his ammunition, I put six rounds of MY ammo in his gun (we were shooting dbl ended w/c's with 2.7 Bullseye except for the quick load stage and we were using Lyman's 358311 round nose for that stage). With my ammo his gun shot right at 1" at 25 yards.

I had him bring a box of his bullets to the club for me to inspect. I brought a box of 1000 of mine. I looked at his bullets and I NEVER had seen such sorry (Appalachian term for TERRIBLE) bullets in my life! I let him open my box and pick bullets at random to examine. I even had a scale so he could weigh them.

The result is that he immediately started improving on his bullet casting and his scores shot up tremendously. His standards were horribly low because he simply didn't know what a good bullet looked like. I gave him some tips on casting (we didn't have the internet in those days) and to give him his due, when he realized what he needed to do he stepped up to the plate and did it.

This scenario is more common than realized.

Dale53

[Bret4207]

Well, you have all keyed on some very important issues. Being my first casting session, I see I was not particularly consistent. Thanks for letting me know that ranges from 171 to 179 grains are too high. +/- 0.6 grains appeals to the engineer side of me.

Yes, as you guessed, I am using a Lee 6 cavity mold. Next time I cast, I will need to investigate the weight from each cavity.

What do you think I should do with the boolits I've got? Shoot them off and try for better next time?

Yup, shoot 'em up. Got to get a little reward for your work. At ranges under 20-25 yards they may surprise you. Try a few groups and see how many odd shots and fliers you get. You'll try for better boolits next time around.

[Dennis Eugene]

Dang good theard here,. Dennis

[Echo]

+1 for what ChuckS1 said - The base of the boolit is the rudder that steers the slug down range. If the base is filled out, square, then the boolit will do well. If not, nope...

[Jumping Frog]

Well, my bases are square and generally well filled out.

Sometimes, it seems like I didn't get a perfectly clean cut on the sprue. There is a little bullet righ spot there, whereas the rest fo them are cut really cleanly.

Other times, it seemed like the lead smeared a little bit against the sprue plate, and the base of the bullet shows some of that smear.

[runfiverun]

clean cut =good high spot a bit late and the tear ='s too soon.
most of my hot and fast casts are the third type.
but they are well filled out have sharp corners a nice color and are pretttttty darn close in weight.
so i don't freak about it.

[bcarver]

cull the 178s. Its only 10%.
As you get better it may be one grain+or- that you cull