boolit weight? how anal, how important??

[mikeym1a]

I've been casting some boolits for my old german Mod 88 rifle, in preparations for shooting, and had a brain storm. I weighed the boolits. They were from two different casting sessions, and I only use the boolit from one cavity, as the other is slightly smaller. After sizing and wrapping, I find that about 82% weigh between 174.0 -175.4grs, with 75% of those being between 174.5 - 175.4. How do you fine people view this? How important is this weight variance? Oh, all weighing was done on a franklin arsenal digital scale, if it is to be trusted.

Thanks:-P

[gray wolf]

Load them and move on, it's of no concern. Fact is it's pretty darn good.
No comment on the scale.

[Tatume]

Hi Mike,

The individual weights of a group of bullets is a sample from a normal distribution. Approximately 2/3 (68.2%) will lie between +/- one standard deviation of the mean weight, and 95% will lie between +/- two standard deviations of the mean (+/-3 sd – 99.7%). The more bullets you include in your sample, the closer your observations will come to the true values. As you improve your casting technique you will be able to reduce the magnitude of the standard deviation. There will still be intervals on either side of the mean that cover the described percentages of weights, but the intervals will be smaller.

There is probably nothing to be gained from weighing and sorting bullets, unless you are a very fine shooter. If your shooting is sufficiently good that it will matter, then you might consider a sorting protocol. One such procedure would be to weigh a large sample of bullets, calculate the standard deviation of the weights, and reject any bullet that is more than three standard deviations from the mean. In that event you would be discarding much less than 1% of your bullets.

For almost all of us, the effort will bear no fruit. So many other sources of shooing error are present that the inaccuracy attributable to variance in bullet weight is lost in the noise. My advice is to consider such matters for academic satisfaction. A clear understanding is worthwhile in and of itself.

Take care, Tom

[mikeym1a]

Thanks for the replies. I did notice a difference in the weights of the 1st and 2nd sessions. The 2nd was more consistent. I was only using a 4 lb pot, so only made so many boolits. As stated, the mould has two different sized cavities, and I only use the larger one. I had read of a shooter sorting his .22 rf target rounds by weighing, and sorting them into .1gr increments, and wondered if it would make a difference here. Thanks for the encouragement. :D

[Toymaker]

A "void" can form in a casting as the metal cools. I read about this and proved it to myself by cutting a round ball in half and finding a "hole" inside. I've also done the math to find the "correct" weight of a projectile and how big a "hole" is left with a 0.5 grain difference. Note that this was all with round ball. Unless the "void" is dead center and with the slower twist of muzzleloaders (i.e. 1:66) this will impact the flight characteristics and POI versus POA. Again, I've proven this to myself by experimenting. So I weigh all my round balls and sort them into 0.5 grain groups. The heaviest are reserved for special competition and the norm are for everyday use. The bullets I cast are 500 or 525 grain and the rifles have faster twist rates (i.e. 1:18). I've not proven to myself that small deviations in weigh (1 to 5%) have an impact. Having a smooth base with a clean, sharp edge appears to be more important.
Maintaining proper pot and mold temperature will minimize the size of the "void". Interestingly rapidly changing barometric pressure seems to play a part too, but that's just an observation from my notes showing pressure changes during casting and reject rates.
Just my observations.

[mikeym1a]

This is a .314 boolit that is paper patched for an antique german infantry rifle, model 1888. I had one out of 150 that weighed 5 grains less than the rest, and 8 more that weighed less than 173grs. I set those aside for recasting. Thanks. mm

[HeavyMetal]

it depends on what your shooting and shooting at,LOL!

For me it wasn't about keeping them all at the same weight, tough to do by the way, but about getting those way under or way over my "average" weight.

My 45 Lee H&G copy is a perfect example:

I alway had a bit of flyer issue and could never put a handle on it till I bought an electronic scale.

This unit allowed me to sort large amounts of cast boolits quickly, way quicker than a beam scale, before sizing and lubing.

As cast were quickly sorted into several batches with a plus or minus .5 grain "standard".

Checking several thousand as cast boolits generally yeilded 3 large " lots" with one or two much smaller ones.

The amazing part of this experiment was the one or two I found that were either 10 grains under or over my specified wieght range!

Because of this my bench rest group sizes became much more uniform, and nice and round, and a bit tighter as they clustered together.

Flyer's, the unexplained ones, disappeared completely but it is a lot more effort than most are prepared to do.

As in all things you get out of something only what you put in for quality ammo some times it calls for just a touch more to get the reward your looking for.

[flashhole]

I agree with grey wolf - that's pretty darn good. Load em up!

[williamwaco]

I used to weigh them into batches of no more than one half grain variation.
It doesn't help a bit.

Load'em up.
Shoot'em.
Enjoy'em.

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Repeat!


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[ku4hx]

If my boolits came out with that small a weight variation, I'd think somebody was playing a joke on me. Like when I was in college. A buddy of mine and I keep sneaking gasoline into another buddy's tank. The way he figured it he was getting several hundred miles to the gallon. Of course gasoline was cheap then and we all burned it out.

Can't take credit for the prank though .... saw it on Gomer Pyle USMC.

[flashhole]

That's pretty good. :)

[gray wolf]

So much for this thread, down in flames.
We will soon be onto how many miles per gallon we get in our cars/trucks.
Said with a smile,--a big one.

[waksupi]

If my boolits came out with that small a weight variation, I'd think somebody was playing a joke on me. Like when I was in college. A buddy of mine and I keep sneaking gasoline into another buddy's tank. The way he figured it he was getting several hundred miles to the gallon. Of course gasoline was cheap then and we all burned it out.

Can't take credit for the prank though .... saw it on Gomer Pyle USMC.

Can I be your buddy? :lol:

[Donor8x56r]

I tried separating boolits by weight last year.When shot it turned out that some rifles notice difference and some don't care.

It looks to me that keeping (made boolits)lots separated is more important than weight.

[ku4hx]

Can I be your buddy? :lol:

If you'd a-been there in 1966 you probably would have. But I see I best not talk about that any more. Decorum and all that.

[sundog]

Weighing boolits is usually not necessary. However, I have proven to my own satisfaction that doing so will eliminate flyers during military bolt matches. The sample is easily in excess of 5K rounds over a period of years. I use a Dillon electronic scale, and the time spent culling match boolits is worth it to me.

[1Shirt]

I also cull boolits with emphasis on the smaller ones 22's and 6MM's. For paper punching I want these exact, and I sort and store them in plastic lidded boxes with multi compartments that I buy at Hobby Lobby. Feel the need for weighing the heavy ones over 300 grains is not needed, but should be closely inspected for flaws, and the culls used for offhand practice. I use a little digital mfg for Hornady that I bought on ebay for 25.00. Think a lot of the issue is the boaring process of weighing and separating. Guess that is an advantage of being old, retired, and having the time to weigh and segregrate boolits.
1Shirt!

[hickfu]

The reason I got into casting my own was because of the weight difference I saw in commercial boolits. I ordered 100 boolits that were supposed to be 425gr and when I weighed them there was a 13 grain spread from lightest to heaviest. I figured I could do better since these were made on a casting machine and were probably never weighed. I weigh all of my casts just to make sure I didnt get a bubble in one that will cause a flier. Im not a sniper or match shooter but I like to try and keep my ammo as close to the same as possible. I also weigh my brass and powder 1 at a time.


Doc

[dondiego]

Wow Doc! Your ammo must be good stuff! I have never weighed cases but I have read that is why Eley .22 match ammo is so good..........and expensive. I am mostly just a tin can plinker but I do cull without remorse, and specifically examine the base of the boollet. Ha! I realized I wrote "tin can". I wish huh?

[hickfu]

I dont know if it helps or not trying to keep everything the same (probably not) My favorite rifle is a Marlin 1895 in 45-70. Its not a bench gun by any means but if I am going to take a shot at an animal I want it to be the most humane one possible so I try (and that is try!) to keep my rifle hitting where it aims.... Its a pretty good shooting little lever gun. I can put 10 shots at 100 yards close enough I can cover with a half dollar if I let the barrel cool down between shots. No leading and all I do is run a dry patch through when done to get out powder residue.


Doc

[dondiego]

Doc- I have that same rifle but I haven't really checked it out fully yet. Soon though. I did just put about a hundred rounds through a Siamese Mauser (Navy Arms) 45-70 bolt rifle last Friday. Several different loads and bullet weights. I still didn't weigh the bullets and the powder charges were dropped from an RCBS Lil' dandy. Only the first few throws were weighed. Shot well.

[mroliver77]

I have found my time is better spent practicing. I have loaded culls and shot them along side of sorted boolits. Out to 100 yards there was little difference. For hunting I do weigh just in case there is a freak. If I were shooting a match I would spend more time. I think brass prep and measuring and getting the right dies and expanders etc more critical.

[pdawg_shooter]

For handguns I lube, load and shoot. In rifles, I allow + or - 1% from a 20 bullet average.

[grampa243]

i would say the size of your boolits will make a difference of how much it helps.. like say the 60gr. boolits for my 223 all get weighed but i don't weigh any of my boolits for the 45-70. and i don't worry about handgun boolits that are getting shot in IDPA type shooting.. but i do weigh for the 243 :)