Bullet weight variance +/-

[Hans]

I just started casting this spring and it seems my bullet weight can vary within the same batch of alloy.I was wandering what kind of variance in bullet weight is acceptable? I'm casting a250 gr for a 45 Colt thanks for any help.

[NVcurmudgeon]

Hans, Much depends on what you plan to do with a particular lot of bullets. I am assuming you are casting for a .45 Colt PISTOL. For pistol bullets a good visual inspection will produce bullets with more accuracy than I can use! Similarly, visual inspection seems to be adequate for rifle bullets used for practice/informal target shooting use. I only weigh bullets for the limited competition that I participate in, and then only for rifles. My rifle bullets are of various designs,weighing between 170 and 220 grains. Using a 200 gr. bullet, for example, if I weigh all the bullets from one casting session the variation will be something like this assuming a lot of 100 bullets, after the bad looking bullets are thrown out.

197.0 to 197.9 gr. Maybe 2 bullets
198.0 to 198.9 gr. Maybe 15 bullets
199.0 to 199.9 gr. Maybe 33 bullets
200.0 to 200.9 gr. Maybe 33 bullets
201.0 to 201.9 gr. Maybe 15 bullets
202.0 to 202.9 gr. Maybe 2 bullets

This is a typical "bell-curve" distribution of variation. If I were selecting bullets for the best accuracy, I would choose them from the two groups of 33 and reserve the rest for practice. That way I would be sure to not be including any bullets with voids in them or variations in the alloy caused by adding different metal, or temperature variations. But, except for the most serious competition, it's not worth the trouble.

[Junior1942]

Sort 'em by Standard Deviation. See http://www.castbullet.com/shooting/standard.htm

I sort target bullets by 1 SD and plinking and hunting bullets by 2 SD. I even sort new cases by SD. It works.

Sorting by SD gives you a reference point--an SD.

[1Shirt]

Hans, I have observed over a period of time that I can reduce the variance in bullet weights at least to a degree is by insuring that I am casting in a rhythm sequence as much as possible. Have found by weighing batches that I run in sequence with those that I take a break and start casting again will show much more variance. Not scientific I know, but just an observation. Have found this particularly true with little 225's and 245' which I like to keep within 1/10 of a grain. I don't that particular with 285's and on up, and mostly just don't weigh them at all. If I were competing with the larger cals, I would probably be more concerned.
1Shirt

[David R]

I find my 22 cal 59 grain boolits vary by as much as one grain. that would be + or - .5 grains. My 150 grain 30 cal vary by the same or LESS. I weigh my boolits for competition only. For plinking or just having fun, its a waste of my time. Pistol boolits? Never weigh them.

When I do weigh boolits, All I really need to do is trow back the ones that are .5 under what I am looking for. I am sure these are fliers, and that is what I am trying to get rid of. I have proven with my 22-250 weighing the boolits will cut the groups in half. This makes it worth my time, but only for serious stuff. Just shooting and having fun is what I prefer.

David

[BruceB]

The topic intrigues me, since it's only on very rare occasions that I bother to weigh my boolits. So...maybe it was time to run another check, sez I, and out to the shed I went.

All the bullets weighed were from random grab-samples of 20 bullets of each type. All of them were cast using "The BruceB Method"....hot, fast, and using the wet pad to speed up the process. All are cast in straight WW alloy, and all received only a quick visual inspection.

Lyman 280468, a two-cavity Loverin-design mould, 20 boolits as-cast:

Lightest....125.6 Heaviest....126.1 Extreme spread 0.5 grains/20 boolits


Lyman 311672, new 2-cavity Lyman mould, 20 boolits as-cast:

Lightest....161.7 Heaviest....162.7 Extreme spread 1.0 grains/20 boolits


I've often wondered about the variables we introduce when sizing, lubing and gaschecking, so for the last type to be weighed I selected my 311467s, which come from a FOUR cavity mould (another variable) and which have Hornady gaschecks installed and four grooves lubed with Felix WFL:

Lightest....185.2 Heaviest 186.3 Extreme spread 1.1 grains/20 boolits


I quote the extreme spread as a gross figure, without bothering to examine the weight groupings within that spread. Fifteen of the twenty 468s fall within a 0.2 max spread, as an example. For the type of shooting I do, the gross spread is perfectly OK, as far as I'm concerned. As others have stated, IF the boolits were intended for SERIOUS matches ...like the Tuesday Burrito Massacree, f'r instance, then I'd weigh them to within a gnat's ass and do all that other happy stuff too. As it is, I'm happy to cast 'em, load 'em and SHOOT.

I'll continue to be happy with just a visual inspection.....it works for me.

[David R]

No doubt the BruceB method cuts down on the ES of the weight of the boolits.


David

[joeb33050]

For many years I have inspected and weighed every bullet I shot. I throw back a lot of bullets, every one with an obvious wrinkle or hole or …. ?
In 2004/2005 I analyzed bullet weights of 10,008 bullets cast in 90 lots with average weights from 58.5 to 445.3 grains. The average standard deviation was .137 grains, with a minimum of .068 grains and a maximum of .294 grains. The standard deviation doesn't seem to vary with average bullet weight.
A good-running mold and pot will cast bullets weighing +/-.2 grains 80% to 90% of the time. It doesn’t seem to matter whether it’s a 150 grain 30 caliber or a 500 grain 45 caliber bullet. When I weigh bullets, I find a stranger here and there. Maybe one in one hundred will weigh substantially more or less than the rest. I believe that close inspection is mandatory, that weighing to eliminate the strangers is important for some shooting, but that weight variation of a few tenths of a grain is not important. Segregating bullets into tenth grain categories makes little difference in my shooting.
Inspection of bullets without weighing is adequate for 90% of cast bullet shooting.
joe b.

[45nut]

Gotta question for ya bruce, I was casting from a lyman 4 banger 311290 the other night and had a tray of water with a soft towel stuffed in there likeI picture you using. When the sprues got to taking forever to freeze I plopped the mold upside down and held it on the towel for a sec and then cut the sprues and dropped the boolits per normal...BUT I had a reaction from the handles,it "seemed" to me as though the quick cooling was sucking the lubricant from the hinge pin. Making opening and closing them very difficult at best and a real PITA at worst. I had to constantly re-apply lube to the pin and work the handles free. I did manage to cast 40# of great boolits in 2 hours despite the extra work though. Should I look to add some graphite or anti-seize to the hinge pin instead of the hard boolit lube I was using? Thanks !

[charlie / sw mo]

i use 6 cavity moulds for all my pistol bullets and usualy cast 40 to 50 lbs at a time. i do not weigh pistol bullets due to the time it would take, most of my pistol shooting is done on steel plates from 15 to 50 yds so i dont think it would help me to weigh pistol bullets. i do weigh all my rifle bullets even tho im not sure how much it helps me since most of my rifle shooting is offhand at steel plates at 150 and 200 yds. it is suprising how much of a spread there is --the picture ill post are 45 cal (405 gr) all cast from wheelweights --i use a pact scale.
charlie in sw mo

[Hans]

Thanks for the input, it sounds like maybe I've been too busy making it to be too much work.

[Old Jim]

Charlie, How close to Branson? I'm about 40 miles NW.

[SharpsShooter]

Well, since I just finished weighing and sorting close to 300 455gr 45-70 boolits, I'll throw in my humble opinion. I'm casting ACWW and using a bottom pour lee pot. I ended up with 125 that were 455gr +/- .5 a grain. Interestingly though, the rest were 458gr +/- .5gr. I suspect the change resulted in alloy mixture changing when I refilled the pot even though the ingots came from the same smelting session. IMHO 3.0gr is far too much variance for competition shooting, but if segregated into groups by weight, I see no reason that they could not be used as a group, without mixing with others of various weights.

[David R]

My concern is .5 of a grain is 1% of a 50 grain boolit.

.5 grain of a 200 grain is only .25%.

Most of my boolits vary by one grain, big or small.

I weigh the little teeny weeny 45 gr 22s and it makes a big difference. I don't weigh the 255 gr pistol boolits.

David

[Buckshot]

............Charlie, that's a very interesting photo you put up. Is that a dedicated scaling setup? It appears you have a very nice reloading room.

.............Buckshot

[charlie / sw mo]

im lucky here--my porch is 60 ft long and i closed it in and put benches along both sides so i wound up with about 80 ft i could use so i dedicate areas . about 8 ft you see there is for sorting--theres about10 ft for5 sizer/lubers i can run up some more pics if you would to see them. i dont know how deleting them works though.
charlie in sw mo

[charlie / sw mo]

im about 12 miles east of forsyth mo on rt 76e--i try to stay away from branson because of the traffic. you ever get down this way , stop in .
charlie in sw mo

[charlie / sw mo]

............Charlie, that's a very interesting photo you put up. Is that a dedicated scaling setup? It appears you have a very nice reloading room.

.............Buckshot
i tried to post a pic of my casting setup but the pic size was 216 so couldnt post it--now iv found a pic taken before i modified it--under 60 so ill post it. i put a 4 in slat under the range hood(right to left) and attached a piece of 1/4 in clear plastic to it with a piano hinge. now all fumes are pulled up thru the hood and i can still get into the pot area by lifting the plastic door.
charlie in sw mo