Got my Pritchet mold!

I cast up a few Pritchets tonight.  Bullets are a little wrinkly so my mold is probably not quite up to temperature.

They are measuring up to .566 just as the drawing says.

Here are pictures:

http://imgur.com/cuDgEoK

However, they are sticking to the core pins furiously.  I am having to tap on the handle pivot bolt several times to get them to drop free.

Do you have any suggestions for a mold release agent to use on the core pins so that the bullets drop free more easily?

Thanks,

Steve

Thanks for the info.  I suspected my mold was cold as the bullets are a little wrinkly. 

I followed the directions on the insert included with the mold, but had not read the sticky posts.

Steve

Tonight I case up 83 .566 Pritchets.  I am casting using a Lee 4-20 bottom pour pot, using pure lead.  To try and alleviate the cold pin problem, I ran my melt at about 875F.  Normally I cast about 750F.  I smoked the mold cavities using a BIC lighter, and then I pre-heated the mold on a backpacking white gas stove.  I’m casting using the longer core pins.

As is common with hollow-base bullets, nearly all of the bullets have voids forming at the top of the core pin.  I tried numerous tricks to prevent this; pouring while holding the mold at an angle, letting the lead impinge on the sprue plate, all to no avail.  I suspect the hotter-than-normal lead is part of the issue; the colder bullets I cast yesterday did not have as bad a void problem.  Interestingly my heaviest and lightest bullets both have perfect base cavities, telling me there is probably in internal void on the lighter bullet.

Here is what the bullets looked like:

http://imgur.com/yQd3RZ5
http://imgur.com/PxCUB5e

The bullets still tended to stick to the core pins, requiring 7-10 whacks on the handle pivot bolt before they would come free.  Towards the end of the casting session they were dropping with 3-5 whacks and I notice that the steel core pins are bluing from the heat.  So perhaps the oxidation is making the bullets drop free more easily and the mold is breaking in.

I love the dual-cavity  nature of the mold and it greatly speeds production. 

I then weighed all the bullets using my RCBS Charge Master 1500.  Here are the results:

Weight in Grains.
549.3
551.8
551.8
552.2
553.2
553.8
554.2
554.3
554.4
554.6
554.7
554.8
555.3
565.5
566.6
566.6
567.6
567.7
568.1
568.5
568.7
568.8
569.3
569.4
569.6
569.9
570.1
570.1
570.5
570.5
570.7
570.7
570.8
570.8
570.9
570.9
570.9
571
571
571.1
571.2
571.2
571.2
571.4
571.4
571.4
571.5
571.7
571.7
571.7
571.8
571.8
571.8
571.8
571.8
571.9
571.9
571.9
572.1
572.1
572.2
572.3
572.3
572.3
572.5
572.5
572.5
572.6
572.6
572.8
573
573.3
573.3
573.3
573.4
573.4
573.5
573.5
573.8
574
574.2
574.7

I arrange the values in increasing order as shown.  This produces a graph that looks like this:

The up-turn and down-turn portions of the graph are where the weight starts to fall off or increase dramatically from the otherwise linear portion of the graph.  So, next I discard all of the data off of the linear portion of the graph and re-graph.  That looks like this:

Ideally I’d arrange the data to produce a bell curve, and then I could discard values that fall outside of a standard deviation, but I don’t know how to do that.  So I just use the linear portion of the graph as indicative of the “average” bullets.  The shape of this graph is typical – I generally find that the colder bullets at the beginning of a casting session tend to be lighter than the rest, and as the mold heats up the come up into line.  If the mold runs hot you get a few outliers on the top end but most of the outliers are on the bottom end as the mold is heating up.

I then take the average of the linear portion of the graph, and set my maximum and minimum weight limits to be +/- .5% of average.  This results in:

571.54 Average
574.4 Max
568.69    Min
5.72         Max-Min

Using this data I re-weighed all the bullets and discarded anything outside the min and max.  This resulted in 61 acceptable bullets out of 82, or a discard rate of 25%.

Steve

Someone on the NSSA forum suggested dipping, too.  I will stop tonight at the local gun store and see if I can pick up a ladle.  The way I understand the ladle casting works, is you turn the mold sideways and press the opening up against the spout of the ladle, and then tip ladle and mold slowly until lead flows into the mold.  So the mold is filling closer to horizontal than closer to vertical, except for near the end of the pour of course.

I don’t relish ladle casting as you have to keep reaching through the oxidation on the top of the melt.  But I’ll give it a shot.

Steve

I went and pulled the instructions for the 1855 and 1859 patterns for the Enfield cartridges.  You can download the excerpts here:

http://4thla.weebly.com/uploads/3/7/9/6/37969349/enfield_paper_cartridge_instructions.pdf

Steve

That is very cool – using an internal plastic tube to make the powder chamber.  For N-SSA competition we use plastic tubes to hold the powder also, so if we ever allow paper-patched bullets this might be a nice shortcut that we can use.

I picked up a ladle Saturday and did some ladle casting.  Unfortunately they only had the cheap-o Lee ladle which is just a stamped steel affair that holds barely enough lead for one bullet.  And the spout is just a divot in the side of the spoon so all the lead, dross and all, goes into the mold.  I tried to continually push the dross off to the side of the pot when ladling out some lead though, and it mostly was not a problem.  Still, I think a better ladle is needed.

Ladle casting resulted in no visible cavities, but did result in “diagonal swirls” or wrinkles on my bullets.  I’m guessing I need to run the lead hotter to account for the heat lost during ladling.  I had turned the pot back down to my usual range of 750-800F; I probably need to stick with the 800-850F I was using the first time.

I got a couple of bullets with incomplete fill at the skirt – again I probably need to go hotter.

After I figured out that this super-high fill angle is what is doing the trick, I went back to bottom pouring at as high an angle as I could manage and still get lead down the sprue hole.  This also seemed to work well though I got one bullet with a void.

What I really need is either a side-pour pot or, perhaps more easily accomplished, a sprue plate with a “lip” around the conical inlet that will allow pouring at a high angle but will force the lead to go down the hole rather than run off the plate.  I’m going to see what I can come up with there.

Steve

Also just wanted to say again how great it is to have a double-cavity minie ball mold.  Man I can crank out the bullets!

Steve