Zeroing process?

[John Westenberger]

My load development process is this (Start to finish)

-Use pin gauges to check rough bore diameter. Slug bore for breechloaders.
-Talk to teammates and see if anyone has a similar gun, and load what they use. Borrow projectiles or molds/sizers if possible (Sometimes the process stops here. My Smith drove tacks with loads I borrowed from a teammate. I just replicated those with Swiss 2f instead of Goex 3f)
-Load up 5 shot groups in 2 gr. increments. Use lube that is known to work. I like Len's lube for everything.
-Load up 1 extra group, I usually do the lowest load to save powder, to foul the bore up and get a little warmed up myself. A clean bore, for whatever reason, seemed to be either dead on to where I was aiming, or a flier. Probably inexperience and me holding the gun weird the first few shots.
-BRUSH in between groups. I don't run any patches at a skirmish. Just brush. Knock the big stuff out and keep the bore dirty, but not fouled.
-Take any group that shows promise, load that again, as well as load 1 grain either direction. Try those. Same process with the fouling group. I've had guns that

I did all this when moving my Zouave from a known Goex load to Schuetzen (After the Goex shutdown), and now I'm getting ready to do it for my new to me Trenton. Will probably use the 7lbs of Goex 2f I have left and try Swiss 1.5 and 2. I can usually get a decent group within two trips to the range, and get it totally dialed in another one or two.

I don't usually weigh projectiles. If they look good, they are usually good. I figure they're all close enough that if a group has a flier, it was either me, or the projectile. I don't factor fliers in group size. I've weighed them before, and it was more hassle than it was worth. When shooting 400 odd grains of lead, 5-10 grains of difference isn't going to throw a shot that far at 50 yards. Your results may vary.

[marv762]

the one thing i do that i haven't seen anyone else mention is a weigh my bullets. so if you shoot a group of 5 they are all the same. have seen people say i have flyers or 2 groups. that will just take that issue away from the start.

also go with 1 grain increases. been doing this long enough that i just start at 46 and go up from there. Marv jr.

[Maillemaker]

I weigh my bullets.

There was a reprint of a Dave Francis article in a recent Skirmish Line where he suggested discarding anything outside of +/- .5 grains. I find this extreme and this would result in very few acceptable bullets if I did this.

I now enter a run of bullets into a spreadsheet and compute 1 standard deviation. (this is where 95% of a sample falls under a bell curve). Typically, this is about +/- 2 grains.

I used to go +/- .5% of average but 1 standard deviation is generally a tighter tolerance.

I don't bother weighing revolver bullets and I don't bother weighing the Moose Wilkinson as it drops so consistently there is no point.

Steve

[PoorJack]

When I'm doing load development for a particular bullet, I do weigh every bullet and use only those at +-.5gr. When making skirmish ammo, I open that up to +-1gr. It's entirely possible to get that level of consistency in casting but you have to be willing to work at it.

[Maillemaker]

Are you ladle casting or bottom pour?

[PoorJack]

Steve-

I have a 20# bottom pour pot from Lee. I have a mechanical thermometer that goes up to 1200f. Wide open, the pot won't do more than about 875F. I have also drilled out the spout on the bottom for a faster flow. One other thing I've noticed is the weight starts to vary as the pot gets under half full so I stop and add lead at about the half way point.

[Maillemaker]

Thanks for the info. I also have a Lee 4-20 pot. I have also drilled out my spout to increase the flow rate. I have an RCBS thermometer. I run about 900F in the pot as any lower and I get wrinkly round balls in my Lee aluminum molds. They shed heat very fast.

I always pre-heat my molds by letting them rest on the surface of the melt. So they throw good drops from the first drop.

I'm going to do another run tonight as careful as I can, and report the results. I'm then going to do a run ladle-cast and compare.

The only mold I have that drops within tenths of a grain is my Moose Wilkinson mold.

Steve

[Maillemaker]

I did another casting session tonight. Bottom pour using an Accurate mold of the Larry Flees Sharps design. I cast as consistently as I could.

I cast 73 bullets. 3 had obvious defects so I discarded them right away.

Here is a graph of the results:



Here you can see the average, plus ways of computing a minimum and maximum acceptable weight:



I chose to go with +/- one standard deviation. This was a spread of 1.8 grains. About 68% of objects should fall within one standard deviation.

The standard deviation is .9, which is less than 1, which means the data is well clustered around the average bullet weight (which one would hope they would be).

So out of 69 bullets, 15 were rejected as over or under weight.


Here are the weights:

499.6
500
500.1
500.2
500.2
500.5
500.8
500.9
501
501.1
501.1
501.1
501.1
501.1
501.1
501.1
501.11
501.2
501.2
501.2
501.2
501.2
501.3
501.3
501.3
501.4
501.4
501.5
501.5
501.5
501.5
501.6
501.6
501.6
501.6
501.6
501.7
501.7
501.7
501.7
501.7
501.8
501.8
501.8
501.9
501.9
501.9
502
502
502
502
502
502.1
502.2
502.3
502.3
502.3
502.4
502.4
502.6
502.7
502.8
502.9
502.9
503
503.5
503.5
503.5
505.1

[PoorJack]

Steve-

Where in the pour series did the rejects occur? From my experience, they should occur at the end as the pot drains. Like I said, I keep my 20# pot at least half full.

[Maillemaker]

I made sure to quit when I got to half a pot.

Not possible to tell when the bad ones happened. I found them as outliers while weighing.

One had flash - the mold must not have been shut all the way. It was overweight.

Another had bubbles/voids around the base of the bullet and was underweight.

Another had a void in its nose and was underweight.

When you look at the graph ordered by weight, you can tell that there is a definite down-turn on the left and up-turn at the right.

I suspect these are cold and hot bullets.