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Maillemaker
03-28-2020, 12:01 AM
Now that I have a Smith, I broke out my Eras Gone Smith bullet mold and cast up some bullets using both 1:20 tin:lead alloy and pure lead.

The bullets cast nicely even with pure lead.

I input the bullet weights into a spreadsheet, and then discarded anything that fell outside of +/- 1 Standard Deviation from the mean.

This is slightly more selective than the +/- .5% that I used to use as a filter.

Pure Lead:
https://i.imgur.com/qEvEptol.png

1:20 Tin:Lead Alloy:
https://i.imgur.com/y8A3qv9l.png

Most of the time under-weight bullets showed wrinkling. Clearly these were cold drops.
https://i.imgur.com/ML3fAYWl.jpg

Here's an example of the culling from under and over-weight bullets.

https://i.imgur.com/kMh9CC9l.jpg

Full-sized pictures here: https://imgur.com/a/PwBgRSL

Michael Bodner
03-28-2020, 06:18 PM
Nice work. However, for your sake, I hope you can get out of the house soon. Clearly you have too much time on your hands ;)

:p:p:p

But again, nice scientific approach!

-Boots

Maillemaker
03-28-2020, 08:45 PM
LOL I'm working from home, so no more time than I used to have. :)

I have always done a baseline weighing of bullets to generate graphs like this to find the +/- cull weight.

Steve

Michael Bodner
03-28-2020, 09:50 PM
I always weigh all mine. I divide them by whole numbers. Once I have them sorted, it's easy to see the distribution. Usually, I go aroun be +/- 2 grains, sometimes 3. I figure 3 grains over 400 is a small enough percentage to have little enough effect.

Kevin Tinny
03-28-2020, 10:33 PM
Hello, Steve:

It appears that Eras has its moulds made by Lee, which tells me they are aluminum. They must be kept HOT.

Wrinkles and, from your photo's, seemingly pour lines down one side tell me either or both of your metal and mould are too cool.

Alum moulds cast ok for me if metal is at 775F and the mould and sprue plate are KEPT amply hot.
I am not sure if alum blocks warp like brass ones can.

I preheat iron blocks by barely letting bottom surface of closed blocks touch the top of the molten lead.
Check with Eras that this is ok for aluminum.
Otherwise you might have to warm via rapid casting of 10 to 15 bullets UNTIL WRINKLES ARE GONE.

Keep pot almost full and replenish in 1# pieces to minimize lowering pot temp.

I use a Lyman egg style dipper with its hole enlarged to .200".

Hold the mould at 90 degrees. Then dip and place the dipper tip firmly in the sprue plate opening and rotate both to upright. Wait maybe three seconds and gently lift one edge of the dipper snout so rest of its contents runs out over sprue plate into pot. This helps keep sprue plate hot.

If no wrinkles, the main reason for weight variations is base edge fillout irregularities. I drop castings onto thickly folded towel so no base edge damage. Try to make the opening of mould interval short to minimize cooling.

An RCBS dial temp gauge fron ROTOMETALS works fine. Pot dials are borderline useless.

Avoid mould casting release preps, widely believed to reduce wrinkles, because thry are usually an alcohol and graphite mix.
Graphite is an ABRASIVE that will eat at the sprue plate screw spot on the top of the block and create a galled area.

Find a way to elim wrinkles.

VR/ Kevin

Rob FreemanWBR
03-28-2020, 10:40 PM
A few years back I weighed and sorted my rounds (Musket, Maynard, Revolver, Ballard and H&P) based on the particular round's median weight.

Bottom-line: I saw absolutely NO improvement in accuracy, and spent numerous hours that I'll never recoup from weighing and recasting "rejects"...

I was, and always shall be, exacting on the WEIGHT (not volume) of my charges. And as for the rounds, if they don't cast perfectly they're sent back to the lead pot.

To put it into perspective, I'm not trying to hit a point target at 1100 yrds with a 165 gr .308 round. Instead I'm hurling a +350 - 460 gr ball at max distance of 300 feet. Granted you HAVE to exercise all of the basic fundamentals of marksmanship each and every time you line up your sights. But in my personal & humble opinion, a 2 gr variance in weight will make only the most excruciatingly minute effect on the point of impact, at most.


Just so I'm clear - in no way am I calling anyone's baby "ugly"! It's a free country (for now at least) so, if weighing your rounds gives you a "warm and fuzzy" - by all means, weigh away my friend!

Maillemaker
03-29-2020, 12:13 AM
Find a way to elim wrinkles.

I actually tossed all of the bullets from that run and started over. I ran my lead at about 850F. I pre-heat my molds on a backpacking stove. On the subsequent batches they now cast great, even using pure lead.

I use the alcohol/graphite mixture on the top of my molds. I find it reduces galling. It's the Moose Juice from Moose Moulds. I know they do not allow graphite in the aircraft industry as graphite causes corrosion of aluminum. But I've had no problems with it on molds and definitely find it limits the galling between the steel sprue plate and the top of the aluminum blocks.

Oh, by the way, I'm using a bottom-pour pot. I only ladle-pour for hollow-base bullets, as I find that is the only consistent way to avoid voids in them. It's why I now avoid hollow-base bullets. :)


I was, and always shall be, exacting on the WEIGHT (not volume) of my charges.

I agree it is probably overkill, especially for an under-100-yard game.

But shooting for me is mostly a mental game. If I have confidence in "the gun", then I shoot well. As soon as I doubt "the gun", then I start missing like crazy because I'm second-guessing myself.

So, elimination of variables gives me confidence in "the gun". I weigh every charge, and almost every bullet. I no longer bother weighing the Moose Molds Wilkinson because it drops so consistently that there's hardly any bad bullet anyway.

geezmo
03-29-2020, 07:22 AM
I like everything the Colonel said.

Barry S.

Hal
03-31-2020, 06:32 AM
I visually cull before bothering to weigh. I'm not as worried about heavy ones as I am light ones, and will often keep all the heavy ones. I think heavy ones are probably just bigger due to temperature variations in the mould and/or melt, Light ones, on the other hand, most likely contain voids. On hollow based bullets, you can often see the void in the top part of the hollow base. However, there are often voids that are totally internal and cannot be seen. If that void is not perfectly centered inside the bullet, that bullet will go downrange in a path resembling a corkscrew.

Kevin Tinny
03-31-2020, 07:42 AM
More:

I have found, beyond temp variations being part of cast bullet weight range:

Minute speck of lead on block face or in vent grooves enlarges cavity when closed.
Inconsistent/lighter hand pressure on closed blocks.
Interruptions in casting rhythm lets blocks cool.

There is a set of block handles that are similar to self clamp-locking VISE GRIPS.
They are used by the long range cast bullet group.
Try Buffalo or Shiloh if interested.

VR/ Kevin

Maillemaker
03-31-2020, 11:30 AM
So, topic-divergent aside here, but one day I really want to figure out how to make swaged bullets with cannelures like they did back in the day.