Puzzled by bad bullets

  • 837 Views
  • Last Post 21 May 2022
  • Topic Is Solved
David R. posted this 02 March 2022

Hi all, 

I have been casting bullets off and on for quite a few years and while I suspect my knowledge of the subject is pretty basic, I'm accustomed to decent results. Today I received a new Lee 405 gr. hollow base mold for my Trapdoor. My technique with large bullets for BPCR is metal that I believe to be pure and add just a bit of tin. I get it close to 800 ºF by my Lyman thermometer. If I don't like how they are flowing I add a bit more tin. So far it has worked and I get nice looking bullets. Today I took a bunch of such bullets that I don't plan to shoot and melted them down. I cleaned the new mold with Naptha  and a Q-tip. I lubricated the mold with bee's wax. With an aluminum mold, I usually just let the casting process warm the mold, expecting the first few to be wrinkled until the mold is warm enough. Today with my metal well over 800º F I was still getting bullets that looked like prunes after twenty five or so bullets. I stopped and after the mold had cooled a bit cleaned it with rubbing alcohol and Q-tip and resumed. By now my metal was about 1000º F.  I've never gone that hot before, but I was out of solutions. After another twenty five drops my bullets were slightly frosty, but still wrinkled like prunes. I'm stumped. They are dropping easily from the mold. I know that there are some knowledgable folks on this forum and I'm hoping that someone may have some insights. I was hoping to shoot a match this weekend, but it ain't looking too good right now. Thanx in advance.  

wrinkles

Attached Files

Order By: Standard | Newest | Votes
Little Debbie posted this 02 March 2022

Sounds like oil in the cavity or venting. I’m curious about your use of bees wax and if it might have migrated into the cavities. If that’s not it it sounds like venting might be and issue. Your temp seems way too high. 720 to 750 is max for me with that type of alloy. Just my thoughts. I’ve had some recent issues with wrinkled bullets that took some head scratching. They were immediately solved by ladle casting. It took longer bottom pouring……this kind of stuff keeps it an interesting hobby

Attached Files

  • Liked by
  • David R.
  • RicinYakima
David R. posted this 03 March 2022

Thanx for the response. By "venting" do you mean air escaping as the metal is poured in? This metal was flowing in pretty fast. I tried to be careful with the bee's wax. I put a dab on top where the sprue plate rubs and on the alignment pins. I kept thinking impurities in the mold, but was careful to clean it first. I use a bottom pour pot. I know that some people prefer ladles, but I find the bottom pour easier and before today more consistent. The last time I used it I opened it up to pour a bit faster, perhaps I've got it dumping too quickly. 

Attached Files

John Alexander posted this 03 March 2022

If I were getting those results, I would clean the mold again. I sometime use another method (boiling water and Dawn) if the first one doesn't work. Try limiting  the beeswax to a tiny bit on the alignment pins. I don't think you can use too little. If the sprue plate is smooth I never lube the top of the mold.  

John

Attached Files

Oldman 1950 posted this 03 March 2022

It could be the batch of metal you are using. Try and emptying the pot and give it a good cleaning and make up another batch of metal and try again. I had a pot full of alloy that would not give fully filled out bullets and a fresh batch of metal after a good cleaning fixed the problem. Sometimes we will get a batch of metal that has Zinc or other metal that is not suited for bullets. It might make good fishing sinkers but not bullets.

 

A. J. Palik

Any day you wake-up sucking air will be a good day

Attached Files

  • Liked by
  • David R.
Duane Mellenbruch posted this 03 March 2022

You have not mentioned your method of preheating the mold and HB pin.  By "prune" do you mean wiggle marks or like bubbles from the wax or oil off gassing as the alloy heats the mold.  To try to lubricate a mold with bees wax I would suggest you make a small Crayon of the wax, twist the end to a fine point and touch the point to the contact point.  That can deposit a small amount of wax as it melts off the tip.  I prefer to use a damp Q tip of synthetic two stroke oil as it is much easier to apply very lightly than the wax that spreads rapidly on the surface.  Stay away from the mold cavity with the lube.

You must have a clean mold to begin with, then get it well heated and try both free fall filling by holding the mold about 3/8" below the nozzle and pour down the center of the hole.  If that is not successful, try placing the mold directly against the nozzle and pour til it is well filled, twist to release the mold from the nozzle and pour a large puddle.  Wear gloves, most of the time  the mold will spurt when filled and it can drop on your hand with resulting pain and injury.

Attached Files

David R. posted this 03 March 2022

Thank you Duane. By "prune" I mean wiggle marks. Wrinkles, not bubbles. I like the Q-tip lube idea. This particular mold doesn't open very wide and it is difficult to get to the lower locating pin. I will try that. 

Attached Files

delmarskid posted this 03 March 2022

I use Neversieze on that mold rather than beeswax. Lee molds are hard to get clean. The last one I used from new got boiled in a strong dawn and water solution while the lead pot heated up. The mold turned dull but it cast good bullets right now.

Attached Files

David R. posted this 03 March 2022

Thank you for your response, Old man. What puzzles me is that this particular batch of metal is just bullets that I'm not going to shoot so I'm recycling them. They were smooth nice bullets. They had lube on them, but I assumed that it would just cook off and act as my flux. After much smoke and some burning I skimmed off the dross and had nice shiny metal like always. 

Attached Files

Oldman 1950 posted this 03 March 2022

I would try and reflux the pot of metal. I use small pieces of Parafin Wax, the size of a thumbnail is enough. It will smoke like HELL and after a few seconds it will burst into flames. I don't wait for it to ignite by itself so as soon as I drop the wax on top of the melted metal, I drop a lit match in so I call when it burst into flames. I have been this method of fluxing for more than 30 years.

Stuff like your problem keeps us scratching our heads. I have about 150 molds and a few keep me wondering what I am doing wrong.

 

A. J. Palik

Any day you wake-up sucking air will be a good day

Attached Files

  • Liked by
  • David R.
OU812 posted this 03 March 2022

Sounds like your mould is not hot enough. Dip bottom part of mould in melt to pre heat before casting. Use synthetic 2 stroke oil and Qtip to lubricate pins and moving part surfaces. Hope this helps.

BTW some moulds can be very difficult.

Attached Files

  • Liked by
  • David R.
John Carlson posted this 03 March 2022

Sounds like leftover lube from the manufacturing process.  I clean problem molds with brake cleaner, then Dawn and a toothbrush.  I also use never-seize for lube.  Temp seems high but if it works for other large caliber molds it should work for this one.  Since you're alloy is made from previously cast bullets that should not be the problem.  I do have one mold that just would not behave until I had cast a couple of hundred bullets, maybe just have to work it until it decides to behave.  just rambling here.

John Carlson. CBA Director of Military Competition.

Attached Files

  • Liked by
  • RicinYakima
  • David R.
OU812 posted this 03 March 2022

This is a common problem with hollow point moulds also. Mould must be hotter than normal before casting begins. Dip bottom of mould in melt for about 30 seconds to preheat.

You guys over stress cleaning.

Attached Files

  • Liked by
  • David R.
  • TRKakaCatWhisperer
TRKakaCatWhisperer posted this 03 March 2022

This is a common problem with hollow point moulds also. Mould must be hotter than normal before casting begins. Dip bottom of mould in melt for about 30 seconds to preheat. You guys over stress cleaning.
Wrinkles are where the alloy freezes.  Too cold - alloy and/or mold. 
IF the mold surface caused the wrinkles it would be the same pattern on each bullet.

Attached Files

  • Liked by
  • David R.
Little Debbie posted this 03 March 2022

By venting I mean the ability for air to get out and not be trapped. Lee HB pins are funny and add structure that seems to trap air some times. I like to have my sprue plates fairly loose. Just enough to keep the base (nose in your case) flat to let air escape the top. Some times a slower fill rate is better. Additionallly I’ll just relieve (barely) the top edges of the of the mold halfs (halves?) where they meet. I think Ben has the best tutorial on this. After reading your response I think you got beeswax in the mold causing your wrinkles. I think it’s a requirement to lube the sprue plate on an aluminum mold. Get some two stroke oil. ( The little Stihl bottle is cheap and my favorite )but any will do. A drop on a Qtip is rubbbed on the top of the mold or bottom of the sprue plate then scrubbed ( with the mold filled and hot) off with the other end every time you feel any binding or galling (close your sprue plate with your gloved hand). My cleaning routine is using aerosol brake cleaning spray to flush the mold liberally and scrubbing with a dry Qtip. I’ve got two or three Lee HB molds that cast well using more or less pure lead when handled as above. I use silver anti seize on all aluminum molds to lube the sprue plate screw and alignment pins/bars. Sparingly and at the beginning of every casting session when the mold is cold. Doesn’t take much on a Qtip. I also smoke the cavities on all aluminum molds.

Don’t use copper based anti sieze on any aluminum!

A combination of blasphemy and idiocy I know, but my aluminum molds are all gems and my old Lees are still casting perfect bullets after more than 30 years of hard use.

Attached Files

  • Liked by
  • David R.
Millelacs posted this 03 March 2022

There are references to both synthetic 2-sroke oil and 2-sroke (non-synthetic ?.

 

What are the differences, and does it make a difference which is used?

Attached Files

BigMan54 posted this 03 March 2022

I've only used Synthetic 2-stroke, it works fine for me. 

Use a q-tip with a DROP on a hot mold. Wipe it on by putting in on underside of sprue plate and top of mold near edges. Then wipe off with dry end of q-tip, Do it fast, Then wipe on sprue plate bolt on top of sprue plate. It will work it's way down. Do NOT reload q-tip, that one drop to start is all you need for each mold,  aluminum or steel.

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

Attached Files

  • Liked by
  • David R.
David R. posted this 03 March 2022

I'm getting a lot of good information here. I was hoping to get in a casting session today, but it didn't work out. When I go at it again I will be sure to have a well cleaned, well heated and sparsely lubricated mold. I also intend to slow my flow down just a bit. I had it dumping pretty fast, not thinking that air may have trouble escaping the cavity. This is my first experience with a hollow base mold. I'm suspecting that it may be a bit of a different animal than I'm used to.   

Attached Files

Little Debbie posted this 03 March 2022

I’ve seen no difference in synthetic or non authentic two stroke oil for sprue plate lube. I was sorry when I ran out of my Castrol two stroke oil several years ago. I like the smell when it burnt in my chain saw and on my sprue plates……….I’d have to look to see if the Stilh brand is synthetic or not. I put the “empty” Stihl bottles on my casting bench. They get turned into a funnel stuck in a flip top bottle to drain. After a week I get months worth of sprue plate lube and I cast at least once a week. So if you have any two stroke motors you have sprue plate lube.

Attached Files

  • Liked by
  • David R.
Duane Mellenbruch posted this 04 March 2022

If you slow the flow too much and cast in a cool area or a drafty area, the alloy will pile in the cavity like a soft serve cone.  Let that tell you how fast to pour.  You might find it better to have a rapid fill produces a smooth casting.

Heat cycling the mold is always a good idea to help reduce any oil residue from manufacturing and it will allow a thin layer of oxide to form on the mold surfaces that makes for better casting.  A couple more sessions and you should be over the hump and casting good bullets.

 

Attached Files

  • Liked by
  • David R.
  • Shuz
David R. posted this 04 March 2022

I want to thank everyone for their thoughtful responses.  This morning I cleaned the mold with brake cleaner and compressed air and smudged it with a stick match. OU812 recommended dipping the mold in the molten metal to pre-heat. It never occurred to me to try such a thing. By the third bullet they were looking like jewelry. Keeping the metal at 850º F according to my Lyman thermometer seemed to be the sweet spot for having sharp, well defined features on my bases. It's starting to look like I may make it to the gong match tomorrow after all. Evidently these hollow bases bullet molds need to be treated a bit differently. Thanx again everyone! 

Attached Files

Show More Posts
Categories
Search
Popular Tags
This Weeks High Earners
Hot Topics
Close