Home Forums Hunting & Shooting BPCR How much variation in bullet weights???

I ran off about 15 lbs of 20:1 405 gr Gov bullets this past weekend and and I'm seeing as much as 1 to 1.5 grain variation in weight between slugs. I will likely sort them into weight classes before sincere loading efforts.

About what degree of variation are you folks seeing, and is there anything in ones technique that can minimize variation?
Thanks, 1Minute

The variation you are seeing is not unusual, although there are those who claim they can cast a batch with less than that. Sorting them into weight groups is a common practice as well.

My sense is that it not so much a matter of weight variation per se, as why. A light bullet might be due to a void, indicating a bullet out of balance. A heavy bullet might be due to the mould not being closed completely. Weight variation can also be due to variation in the heat of the mix.

I generally weigh and sort my bullets, then discard those at the high and low ends of the distribution. For serious shooting, meaning long range competition, I like to load bullets from the center of the distribution. I can usually get 100 or so that don't vary more than .2 grs.

Hope this helps.

Paul

Hoo boy, that is hardly unusual. I learned rather quickly that there is a HUGE difference between casting ANY handgun bullet and the enormous slugs the big guns use. Paul gave the best advice on selection. As you go along the technique of casting lead boxcars will improve.

I segragate into 1.0 Gr variance, ...and shoot most everything I cast, having discarded the initial few from initial approach to mold temp ( I do preheat with MAPP ).

Tried sorting to smaller variance over the years, ......extra work was all it looked like, and the 1.0 gr sorting shoots wonderful results.

I Minute, ....I'd say that a 1.5 gr variance over a long run of slugs is VERY good casting results.

Good Shooting !

GTC

To elaborate a bit on what I said, if you weigh and sort a batch bullets by .1 gr., and lay them out in rows on a table, you will see a bell-shaped distribution. I'm not saying this is necessary, but it is a neat example of practical statistics. When I talked about a premium batch varying maybe .2 gr., I meant cherry-picking a couple or three rows out of the center of the distribution.

Come to think about it, I took this picture some time ago. IIRC, the ones on the pink stickies were the low end culls. This doesn't appear to be one of my better batches, but it does illustrate what I'm talking about. Note the cardboard air shield around the PACT scale.

1minute I doubt you'll have any problems with those bullets dumped in a box lubed sized and loaded just as they are. When you start talking about 4 and 500 gr bullets 1-2 grs don't really amount to much.
It takes 4 grs in a 400 gr bullet to amount to a 1% variation.
The bullets being the proper size for your barrel, and using a good lube will likely do more for good accuracy than obsessing about 2 gr variation in bullet weight.

Thanks for the feedback. I was mostly interested in whether I was practicing some obviously sloppy pouring technique that could be improved upon.

I'll likely do some sorting and batch them for loading. If nothing else, just to fill some time one dull evening. The only obvious visible difference I see in examining those slugs is that some exhibit a very tiny (technical term) irregularly shaped void where the sprue was severed. When pouring, lead levels are well above that point as things go solid, so I don't have the remotest idea as to how a void can form. I'll try playing around a little more with temperature and see if that has any effect.

Rgarding competition.... I'm old and likely don't have the eyes for that, but I still like to milk everything possible from my tools.

As an aside, I'm presently using a RCBS mould advertised as a 405 grain gov unit. The slugs are coming out in the 419 grain range. After I've torched off a few, I'll likely step up to something in the 520 to 530 range for reaching out.

Thanks again and keep the powder dry, 1Minute

HEHEHEHEeee haw, as for the old guy business , 3 of us that've been offering up opinions and advice seen our 50th birthdays several years ago. So I suppose you'll need a better excuse than that one for not shooting competition. lol

HA, Ranch, that's for sure. 39 ain't my age, it's the year I was born.

Paul

Edited to add:

1minute, I wouldn't worry about the little divots where the sprue was cut. That seems to relate to how much the bullet has cooled before you cut it. Just make sure the sprue plate stays flat on the mould surface. I don't rap the sprue plate to cut the sprue, I push it over with a gloved hand, and I keep a bit of pressure downward as I do it.

Paul,

don't let them youngsters give ya a hard time just 'cause you're "old". I'll be 72 in July and I don't let that small stuff bother me. I usually sort cast bullets into 1 grain lots, and that's good enough. The ol' 45/90 will put 'em into 2" groups at 200 yards with a case full of the holy black.


Jim

Try 61 birthdays. When I vacate one of these monitors, it's 3 or 4 minutes before I can really focus at a distance. 1Minute

Man I must be the young pup. I'm 60.

You guys give me a lot of encourgement. I now have glasses but with slight correction. My right eye has an astigmatism but fortunately my left eye is my master eye and with glasses on most days I can still read a stop sign at a hundred yards.

No excuses for me not to shoot.

Knock off the "old Fart" dialogue.

I'll dredge around, ...lookin; for this "bell curve" bs,

and how we should be all puckered (SP?)

I've slung 'em in there ( he sits back, ....reflects) than says,

YUP.

Obsession might be a good thing for some,

and if you think obsession is good for your way of shootin', I says go for it....

"Never Sweat" is right there,....

and the accuracy potential,

Chuckle, giggle, snort,...

Hittin' an 18" gong at well over 1100 yards ,repeated accurate.


./.....I'm grinning,...a dumbschit.

Doin' it's a little over-rated,

It's no big stunt,

Evil Twin just pulled off a "stunt"

No meat ruined....." Bang Flop"

I'm laughin' here now./..

Newfie guides goin' " Holy Smokes, did you ever see a MOOSE go down like that"

Some old black powder gun, I guess.

Yup.

GTC

As the morning sun rises over the Arizona desert

Crossfire writes BPCR haikku.

Good morning, all.

Paul

Paul - I see you were up early again this morning - to watch the snow I guess. Sucks for field work, let me tell ya....

Brent

Sort of amazing I suppose. When the alarm comes on in the morning the radio is always set to K2 in Casper, but many mornings this time of the year, WHO is overriding, and the amazing part is that lots of times you couldn't tell any difference in weather forecasts and current conditions between the two.
Cold and snowy here this morning.

"As the morning sun rises over the Arizona desert

Crossfire writes BPCR haikku."

Well before sunrise, and damn cold for this part of the world.

Been doin' the "NightHawk" routine for the last little while....

Can't Say whats goin' on down in the San Pedro valley, just below.....I damn sure not stickin' my nose into it, either.
Suffice it to say that there's been a lot of activity, and some of it has run uphill, just to the North of my place.

We do need to get a handle on the Border.

GTC

i was going through some of my cast bullets and found a white powder on them that was slippery like graghite.any casters seen this before & what is it?
i cast some big lead 680grs.,630sp,down to a 200gr real bullet.all in 457cal and use my lee sizer to get the proper size of my bps.what percentage do you think would be acceptable for quality control?thanx bp shooter

bpshooter,

If I understand your second question, the answer has been suggested in the various responses in this thread - It depends.

If I am loading for a big match, I want to be dammed confident that if I miss a distant target it was because I didn't break my shot well, or misjudged the wind or something, NOT because I loaded an imperfect bullet, or did something else sloppy in loading my ammo. IOW, I want my ammo as perfect as I can make it. Obsessive? Yeah, probably. I will sweat the small stuff.

OTOH, if I am loading for one of our local buffalo matches, I'll cut some corners. I might use a batch of unweighed bullets, or those from the ends of the weight distribution. I'll probably dump the powder straight from the measure instead of weighing each charge. I might use the dregs of an odd lot of powder. Keep in mind what Ranch said, a few grains variation in a big 500+ gr. bullet amounts to only a small percent of the total weight. So, YOU set the standard.

About the stuff on your cast bullets, I'm guessing that it's oxidation.

Paul