Poor fill out on one driving band Lyman 452651?

[Snyd]

I just got a lyman 452651 mould and cast up a few bullets with it yesterday. WW's with some 50/50 added. The boolit drops at .452 at the 2 crimp grooves, .451 or less at the froward driving band and .452 at the bottom band. Gas check shank is fine and the boolits look good otherwise. I used to other moulds and cast out of the same pot. No problems with fillout on them. Any ideas on what my next step should be? I need to determine if it's me, the alloy/mould combo or a problem with the mould. Or, is it not a problem but a feature of the mould :D

[Trey45]

It's quit possibly a defect in the mould. If you're using a bottom pour lead pot, try pressure pouring just to make sure it's not improper fillout. If it's consistantly dropping undersized front bands, it's got to be the mold. Lyman will say it's within spec's and send it back to you.
Erik will make your mold right here:
http://www.hollowpointmold.com/
He does excellent work. If memory serves me right, there's also a couple guys here on this board who will do that type of work, I cannot remember who they are though.

[Lloyd Smale]

look to see if its frosted where its not filled out and see if its between the two cavitys when the bullets are in the mold. Sometimes with tin alloys and a steal mold you will get a hot spot there. If so slow down a bit.

[Shiloh]

Is it vented properly in that area?? Take a close look. Make sure the vents aren't plugged.

Shiloh

[sagacious]

Is it vented properly in that area?? Take a close look. Make sure the vents aren't plugged.

Shiloh

This would be my first check, too. Fills-out well everywhere but at one driving band? Proper venting at that location is the first suspect to eliminate. Use a needle or very sharp tool to trace the vent lines and make sure none are plugged/blocked at the very edge of the cavity in the problem area. Very often, vent lines are blocked in a new mold. You will need to use good lightling and a hand lens to check the vent lines.

Also be sure to check that the mold is perfectly clean in that area-- a bit of oil residue, cutting fluid, or something similar will also cause your problem.

Your alloy sounds fine. Make sure the mold is up to the proper casting temp, as different molds have different temp requirements.

Check all these concerns, plus check operator error and make sure your pouring technique is 100%, flux your melt, etc, before seeking another fix. It is completely normal to have a new mold not cast perfect bullets the first session or two. Hang tight, try it another time or two, and your fill-out problem may disappear-- sometimes there's only so much you can tell from the first session.

[Snyd]

Wow...This site it great and you guys are awesome! Thanks a bunch!

[Snyd]

Okay, I finally made it back for another casting session today. I used 5lbs ww to 1lb Lino mix and now have a thermometer and cast at 750-775, good fill out, sharp edges but still the same problem. The only thing I did to the mould was make sure the vents were clean. I also cast up a bunch of boolits from a different mould that turned out beautiful. All nice and shiny with good fill out and nice sharp edges.

So, I now have the mould soaking in mineral spirits. I'll let it soak a day or to and then scrub the heck out of it and try it again.

How hard would it be to lap this thing, would it be worth it?

[sagacious]

Snyd,
Make sure that the vent lines that contact the edge of the cavity at the driving band are not blocked. You will probably need a good magnifying lens to be able to see if the vent is blocked there. Run a very sharp scribe along the vent lines and into the cavity to make sure there's no tiny burr at the very edge. Vent lines blocked in this manner are fairly common, and can cause exactly what you're describing, but the problem can be very difficult to see with the naked eye.

Before considering lapping, double check the vent lines. Try again after scrubbing the mold, and let us know how it went. Best of luck.

[Snyd]

Okay, will do. Thanks again.

[saz]

Hey Snyd, how is that boolit working in your Puma?

[Suo Gan]

look to see if its frosted where its not filled out and see if its between the two cavitys when the bullets are in the mold. Sometimes with tin alloys and a steal mold you will get a hot spot there. If so slow down a bit.

+1 on that

[shotman]

Kroil works try it, lead dont stick in the vents or any place Smokeing will fill vent lines
talk to your denist and get a pick that they broke you can sharpen them and they work great to clean a mold/mould what ever

[armyrat1970]

Not meaning to hijack this thread, but vent lines? Have always read a lot about vent lines in a mold.
What exactly are the vent lines?

[Suo Gan]

They are the grooves milled into the face of mold blocks...sometimes they are absent, sometimes there are a lot, sometimes just a few, sometimes just one half has them, some ambitious or frustrated souls have done it to their blocks themselves with a file... All meant to vent hot gases away from the boolit so wrinkles, rounded corners and air pockets don't develop so easily. Some say that vent lines are unneeded silliness, some say the more the merrier. Boolit casters are a fickle lot. But whatever works, works.

[dubber123]

There are alot of good suggestins, but I have another. I have had quite a few NOS moulds, (New, Old Stock), that have sat for years with the packing oil in them. Eventually this oil will harden to the point it is very hard to remove. I have had a few, that although they looked spotless, would refuse to fill out in a certain area. Using a VERY sharp awl, I scraped the offending area, and sure enough, some hardened oil flaked out. problem solved. Good luck,

[Suo Gan]

I have had good luck by boiling blocks with a detergent. I usually cast enough of what I need for a year, then I pack them away in grease, just boil it off next year.

[Edubya]

Snyd,
Make sure that the vent lines that contact the edge of the cavity at the driving band are not blocked. You will probably need a good magnifying lens to be able to see if the vent is blocked there. Run a very sharp scribe along the vent lines and into the cavity to make sure there's no tiny burr at the very edge. Vent lines blocked in this manner are fairly common, and can cause exactly what you're describing, but the problem can be very difficult to see with the naked eye.

Before considering lapping, double check the vent lines. Try again after scrubbing the mold, and let us know how it went. Best of luck.

It would be good if you set up a divider wall (perhaps a cigar box) for your boolits to drop separately into so that you can identify exactly which one is not filling out.
Use a Q-tip to trace the line all of the way to the cavities.
EW