smooth bullet molds

[KenH]

Hello all - I have a couple of questions perhaps ya'll can help me with. I'd like to make a smooth bullet for PP'ing in smokeless powder, perhaps 43 Spanish and 45-70 rifles.

With a smooth sided cavity mold, will a bullet drop out of a solid mold ok without it being in two pieces? OR - does a mold require two pieces to open to allow bullet to drop out? I'm talking low production here, just a few bullets cast at a time - like 30 or 40 or so bullets?

Also, would a brass solid mold drop the bullets any better than an aluminum mold? I can do either one, got brass or aluminum round stock large enough to make mold with.

Thank ya'll for any comments or suggestions.

Ken H>

[Bent Ramrod]

If you've machined a good, round, smooth cavity, the casting will for sure fall out of the mould when the sprue plate is swung away and the mould inverted. However, even slight reamer marks will begin to catch the casting as the mould heats up and the fillout gets more exact. If not excessive, a little tapping usually will get the casting out anyway. I've never had to struggle, because all the moulds I use are two piece; I just notice that I am likely to get the casting on the floor without opening the blocks if I have it pointed in the wrong direction when I knock off the sprue.

Ideal had, at one time, a "cylindrical" mould, a base pour cylindrical cavity in a one piece casting with the nose shape in an adjustable punch. This could be tapped or pressed with the sprue plate swung away to eject the boolits.

I only have one brass paper patch mould. It appears easier to make a really mirror finish in brass, while ferrous alloys often have tiny circular tool marks on an otherwise smooth surface.

[bangerjim]

Molds only drop boolits proportional to the cleanliness of the cavity....that's lack of dings and burrs. Also as they heat up, drops become more difficult.......best to slow down and let it cool a bit.

I have a couple NLG molds for PC'ing and boolits drop from them just as easy as with grooves. You gotta have a split cavity mold with sprue cutter or you will NEVER get the slugs out!

I use Fe, Al, and brass molds all with excellent results. You just gotta treat Al molds a bit nicer!

banger

[KenH]

Thanks for the comment folks - I'm just learning about this making molds business. We'll see how it turns out.

Ken H>

[joesig]

If you are just going to bore a hole in a block of metal I would suggest that it has some draft to it. (Cone shaped.) You can probably do that with a hone.

Baring that, if I understand how you want to bore a hole in the center of a rod, I would suggest using an ejection method similar to swaging with an ejector punch. Your cores aren't just going to fall out when you invert the mold.

I don't know if that method will really save you much over a split mold design.

I would use aluminum.

[KenH]

Thanks for the info - I did drill one in a solid aluminum rod, but at last minute I put the ejector rod you're talking about in nose end. That allowed it to punch out nicely. I think "if" it was perfectly smooth, it might drop anyway, but my test was about .002" cone shaped, but the big end of cone was at nose end - doesn't work well that way. I think what happened I drilled, but didn't lift cutting bar often enough allowing shavings to pack in at bottom causing that extra .002" expansion at bottom. I think that's also causing the finished hole to be cut a bit oversized all the way up 'n down.

Hey, this is mostly a learning experience anyway - keeps the old brain active and a LOTS more fun than working crossword puzzles.

Thanks again,

Ken H>

[longbow]

Yes, I make moulds much like the Ideal cylindrical moulds for .30 cal., .44 cal, and 12 ga. slugs with good success. A drill is not the tool to use though as they leave a rough hole. Better to make a "D" bit or buy a reamer of the right size ~ for instance an N reamer is perfect for standard .30 cal giving cast boolits of 0.301".

You can drill then lap using a slug cast in the hole you drilled but you will most likely have to drill considerably undersize then lap to final size using valve lapping compound. I make "D" bits and ream to slightly undersize then do a final lapping to make sure the bore is smooth and I do add a very slight taper to ensure release (maybe 0.0005"). I also use an ejector pin which is usually a nose form or HP pin.

You can paper patch these or knurl and tumble lube which I often do. You just pick the size you want as knurling raises the surface by up to about 0.003".

There are several threads on the subject with some quite good posts and nicer moulds than I make... though mine cast to size and they shoot very well.

Look for Heathydee, he did a good write up and has made some every nice moulds.

Longbow

[KenH]

Thanks LongBow - Yes, a "D" bit is what I used. I took a 1/2" W2 rod, turned to size I wanted final cast bullet to be. Then took that to milling machine, clamped in vise, indicated to be sure it's exact parallel, used a 3/8" endmill to cut exactly half the diameter to form the "D" tool.

I only used a 7/16" drill bit to make the pilot hole, then ream with D tool

When you mention " knurl and tumble lube " do you mean without paper patching?

Ken H>

[longbow]

Yes, without paper patching. I tend to be lazy and paper patching really wasn't needed for my .44 Marlin so I made a slightly larger cavity at just about groove diameter and made a knurler for boolits. It raised the surface by about 0.003" so cast, knurl, tumble lube, load and shoot. Not patching required.

Actually you can tumble lube smooth boolits at groove diameter or a bit over and they shoot pretty well as is. So far I have gotten the best accuracy from my lee Enfield .303 using a smooth boolit at about 0.002" over groove diameter, tumble lubed with no knurling, load and shoot. I use COW filler though as they are plain based so limited velocity potential due to gas cutting. COW helps some so they can be pushed a little faster. It works for me anyway.

However, for your purposes these types of moulds make great PP moulds. I keep intending to make a multi cavity mould this way but have not got to it yet. I have too many unfinished projects already and the single cavity moulds work well enough for my needs.

Of course I also have many commercial moulds too so really don't need any more moulds (I always want more though!).

Maybe I should add as a more complete answer to your question "When you mention " knurl and tumble lube " do you mean without paper patching?" Actually both!

When I tried my 0.301" smooth boolit for my .303's it did not work well even patched past groove diameter until I decided to try knurling the boolits to raise diameter to bore size then paper patched after. That did it. The boolits at 0.301" were too small for my 0.303" bore and I guess were either slipping in the patch or the patch was not cutting properly for release. In any case, the slightly larger diameter gained by knurling worked.

I would not bother if I were doing much paper patching for the .303's though I would just make a mould to cast at 0.303"/0.304" then patch to groove diameter.

Then as mentioned, I do make larger moulds specifically for knurling and tumble lube. So, yes, both!

Longbow

[KenH]

Hey Thanks for such a nice long answer. I'm learning a LOTS from ya'll nice folks on this group.

A question please - with a D tool cut to .345", what would you expect the final cut size to be before polishing? I'm getting an oversize hole, but I think it's due to allowing too much shaving to build up inside the hole. I think I need to life the bit often to keep shavings cleared - comments?

Also, does a mold normally cast "exact" size of mold? OR - is it common for it to cast 1 or 2 thousandths over size of mold bore?

Ken H>

[longbow]

I find that if I drill or bore to just a few thou under then hand turn the D bit in I get pretty much exact D bit final size. However, ir I use the lathe and "drill" the final hole with the D bit I get oversize holes by a couple thou. I think the fast spinning of the lathe under power and chips do it.

In fact I ruined a Lyman 314299 mould that I was removing gas check shanks on with a D bit I had used to make a .303 mould. When I used it with hand power it cut exact but when I did the Lyman mould I chucked the mould in the lathe and used power but fed the D bit fairly slowly and wound up with a much oversize base on the cavities. I think rapid spinning and slow feed were responsible.

Try using hand power and fairly fast feed in but to do that you can only be removing a few thou.

Your mould will cast slightly smaller than the cavity. I always start undersize then lap to finished diameter to both ensure I get exactly what I want and also to add about a 0.0005" taper.

Longbow

[KenH]

Thanks for the tips Longbow - sounds like two different tools are needed, well 3 tools?

1. I've got a drill bit I've shaped the tip to pretty close match the shape of bullet nose to drill the pilot hole at .435"
2. A "D" tool ground perhaps .005" below desired size to turn in lathe?
3. A "D" tool ground to desired diameter to work by hand to finish size?

Does that sound anything like right?

"IF" I had to count my time at $1/hr it would be a LOTS less expensive to buy my molds, but since I'm retired, my time is pretty much my own time. Good for learning - keeping the old brain active.

Ken H>

[longbow]

I would say that should do it. You could save a step in making another tool by buying number or letter drill bits close to the finished size you need. A little more cost but less time spent making tools. If you have time then it probably doesn't matter.

Hah! I have often thought about how much time I spend making "cheap" moulds. Oh well, there is satisfaction in doing it yourself and also in getting boolit diameters you need without waiting for custom/semi custom moulds. I do love my Mihec moulds but waiting for over a year is painful.

On the finished size issue, I found that using power resulted in oversize cavities I think simply because of the relatively rapid rotation of the work piece and relatively slow feed of the D-bit. By rotating the lathe chuck by hand while feeding the D-bit with some force results in steady cutting with few revolutions of the work piece. Possibly using back gear and feeding fast would solve it too. I have not tried that.

Longbow

[KenH]

Thanks for the comments Longbow - there are two ways of learning, personal experience, and learning from other folks knowledge, and many times learning from other folks saves re-inventing the wheel {g}

I'll follow up in a few days my results.

Ken H>

[KenH]

OK, h​ere's an update on my mould work. This is a mould for a Swedish Rolling Block 12.7X44R that I'm using 50-70 brass for, with only turning the rim a bit. I slugged the bore of this Rolling Block​ and best I can tell the bore is about .480"-.482" with a groove of .510" - .512". I've read that is about normal for the Swedish Rolling Block. The rifling does look deep for sure.



Above​ is the mould I made over the weekend - works good. I chucked the two aluminum blocks in a 4-jaw chuck, drilled pilot hole with drill bit, then finished with a tool I made from 1/2" W2 steel rod. The bullet is pretty round nose, maybe I need to reshape the nose of tool for more of a taper on nose? Comments?

I've not put any vent lines in yet - but it does seem to fill bullets pretty good. Any suggestions on need for vent lines? How best to put vent lines in mould?

The mould drops a .492" bullet at 425 grains. The bullets shown are as dropped from mould and measure .491" to .493". While not perfect it is decent. The sized bullet is below from a die I made for sizing down to .488". I wish to try PP'ing a few of the smooth sided. As suggested by Longbow I will use a file to "emboss"​ a​ ​knurl on ​the sides that will hold lube for trying lubed bullets. I plan to load up a few today or tomorrow and try them.



The sized diameter of .488" is a bit over bore for PP'ing, and perhaps a bit small for lubed bullets? BUT - seems like it's a decent starting place.

Thanks to all for suggestions and comments. I've sure learned a LOTS from this group. I've done much more reading than posting.

[Ken H<

[montana_charlie]

KenH,
Because your images are contained in emails that exist in your Gmail account, you can probably see them just fine.
But, for those of us who cannot logon to your Gmail account, they are invisible.

Just so you know ...

CM

[KenH]

Thanks - let me fix that. I wondered, but when I could see them in preview I thought it was working.

Edit: I just fixed the photo issue - let me know if there are any other issues.