Boolit design

[hemmjo]

Hello everyone, some background before I ask my question. I am new to the cast boolit hobby. So new that I have not even cast any boolits yet. I still have trouble spelling boolits. I have used with great success, the old lyman .45 cal round ball mold that I got for my dad to make ammo for his sling shot long ago. I am a retired industrial technology teacher with all of my fingers. I have lots of experience teaching safe work habits. Used to teach kids about machining and foundry practices. They ran lathes, cast brass and aluminum, etc. I also have a quite a bit of reloading experience from 30 years ago, before life got in the way and the farmland around our home started growing houses instead of corn, beans and wheat. I used to shoot a lot and reload for my 22-250 and .221 fireball. Still have all the tooling from that.

I know how to safely work up a load. But I have always had a loading manual as a starting point. Just saying that I have the safety mindset and mechanical skills required do what I am going to ask, just no experience in this specific area.

I mentioned in the old military rifle section of this forum, I have my grandpas S-147, 1936, 8mm Mauser. The bore slugged at .326. It is in great shape. I have fired a few rounds of surplus military ammo. Accuracy was not spectacular. From standing I was able to hit 3-4" logs and scatter a few rounds into an regular sized paper plate at 50 yards. I know that is not great testing data, but it was fun anyway!! I am guessing that since the .324 bullets were rattling around in the .326 bore, that may have been a contributing factor accuracy. I now have reloading dies for it.

I have found are no commercial bullets correct size, and only one mold even close is available. There is no point trying to work up a load with bullets that I know are too small start with. So I am going to make my own mold. I have a small machine shop in my basement, all old school no CNC, machining skills are not an issue. I can make whatever shape I decide on. This will be part of the fun for me, the reward will be shooting whatever the result is.

Bullet, oops I mean boolit, design is the issue. I have read a lot, and have many of the drawings for various boolits available in .324. I could just copy one of these designs and make the mold a bit larger. Getting to my question, the grooves in cast boolits are an issue. It is a bunch easier to make a mold with no grooves.

I have been reading the power coating threads. That seems to be the way to go since I have never done either of the lubing processes. All of the threads I have read are simply power coating grooved boolits instead of using various other lube methods. Some info I have found mentions the grooves give the lead someplace to deform into as it engages the barrel. This puzzles me since copper jackets do not have any place to deform into as they are fired.

While reading this morning I found this, "The polymer coating on the Federal Syntech bullets prevent harsh metal-on-metal contact between the bullet and bore, eliminating copper and lead fouling. In internal testing against conventional FMJ bullets, Syntech produced an average of 12 percent less barrel friction and 14 percent less heat. It also eliminates lead and copper fouling. Syntech bullets keep your gun cleaner, longer, so you can shoot more—and shoot better."


This appears to be powder coated commercial bullets with no grooves. I have not found any rifle bullets that are polymer coated. This discovery pushed me over the edge, now I am thinking that I am going to start by making a mold to throw a boolit about 180 grain x .326 then powercoat to bump the size up a little.

No need to address how much time this will take. I also know there is also software available for bullet design. I am planning to just take a common design and try it with no grooves.

My question, am I totally out of line in my approach to this? Any suggestions or comments are appreciated.


Thanks for your time.

John

[Dusty Bannister]

I would think it a lot easier to buy the Lee C329-205-1R and size down if needed. If the groove is .326" this bullet might cast about .329 or a bit larger. Sort of a gamble with inexpensive molds. With the lathe, you can make your push through sizer to whatever you like. Starting bullet casting, starting mold making, and starting with an unproven design seems to be a rather steep learning curve.

If you do not like the C329-205-1R then look at the C324-175-1R and consider lapping the mold larger if needed, or as you have already mentioned, powder coating. This will give you a starting place in mold making since you will probably need to fit for both the bore and the groove of the barrel, and of course the throat will tell you exactly how large a cast bullet you can use.

The bore will dictate how large a bullet nose you need to guide the bullet down the barrel, the groove will give you the minimum diameter needed to seal the barrel, the throat will give you the maximum diameter of the neck of the cartridge of a loaded round which is the thickness of the neck of the case x2 plus the diameter of the body of the cast bullet. You need some clearance for bullet release. Good luck.

[OS OK]

You might get to adjust your alloy to make up the difference in diameter and use a standard mold of your choice.
PC'ing the casts with quality PC will increase them .001 - .002" outside diameter with the first coat. There's a plethora of methods here in the forum.
Then there is the method of increasing diameter through lapping the mold. Depending on where you put the lapping compound and how careful you are you can increase certain areas of the casts...ie. the drive bands only...


Attachment 192855

[runfiverun]

if you just want to make a slick sided mold and powder coat it you should be fine.
I personally would put a step on the base for a gas check.

if you want lube grooves and just want to make the mold yourself.
then drilling the pilot hole for the drive bands the same size as the gas check [minus tolerance] then J-cutting the lube grooves on the shank would give you your diameter.
and drive band portion.

a modified D-reamer would be appropriate for cutting the nose.
pre-drill the nose depth and use the end of the plunge cut as the final nose depth, then just remove the material from around it. [modify the end of the bit to give you the final shape on the tip of the nose]
you will probably want to make the nose the diameter of the inside of your rifling. [bore]

when your done with all of that.
make some boolits and measure them.
then prepare to lap out the mold to your final diameter.

[FredBuddy]

hemmjo:

Your approach seems fine, and appears to be based on the experience of many members here.

Since I am not a machinist and I don't have lube-sizers, I use the Lee 324-175 mold and powdercoat those boolits to 325. They work great in my Yugo 48 8mm - and cost very little.

The addition of powdercoating and NOE push thru sizers to my reloading has increased my options significantly with very little expense.

Whatever you do, the personal satisfaction is worth the effort.

[reddog81]

I wish you the best of luck with your project. I wish I had those tools and skill set.

If it was me I'd try the .324 with a thick coat of powder coat. You should be able to get up to .326 pretty easily. A .329 mold sized down to .326 or .327 would also work.

[RickinTN]

I might suggest sizing to the throat, not the bore, assuming the throat is the larger of the two. A throat pound cast is the way to go to get the throat dimension as well as other important dimensions.
Good Luck,
Rick

[Wayne Smith]

My best advice is to go over to Dan' site, mountainmolds.com, and play with his design program. He has an excellent boolit design program that can teach you a lot about boolit design. Especially with your background, asking him a few questions on his forum to clarify some of his thinking and you will be able to answer most of the questions you have yourself.

[hemmjo]

Thanks for the input, I think I have an good idea of where to go from here. Will let you know when I get some lead melted.

[JonB_in_Glencoe]

Midsouth carries a couple Lee special order molds for cheap $$$.
while you may want a project? one of these two molds are another option.


https://www.midsouthshooterssupply.c...roduction-mold


https://www.midsouthshooterssupply.c...roduction-mold


I have both of these molds, the Karbiner drops a boolit that measures .328 (235gr)using 94-3-3 alloy and
my casting techniques. The MAX drops one that measures .326 (240gr)

[waksupi]

I quit slugging rifle bores. I fire some rounds, then measure the inside of the case neck. I want a bullet that slides in with a bit of resistance. Then partial neck size the brass when reloading. This fits the bullet to the throat. Works well for my, YMMV.

[hemmjo]

I finally got some time to do some actual work on this project. Just testing what I have learned so far. I worked from a design I found at Noe. It is not exact, but that is where I started, I left all of the grooves off since I am going to power coat.

I made a simple form cutter from tool steel. Have not hardened it yet since I am just cutting one piece of aluminum for now.

Made a simple one piece mold, since the design has no grooves. The sprue cutter is from a round ball mold I have. I may have to make a regular two piece split mold as air escape is an issue with this design.



Cast a few boolits. The form tool I made needs a bit of work to clean up the profile. You can see some little grooves around the nose of the boolit. Then pushed one through the barrel from the breech.

I made the cutter for the mold 0.327 since the original slug I made before I started this project came out 0.326.

I cast 12 boolits. (Honestly I kept 12, the bad ones went bad into the melt) As cast they are from 0.3225 to 0.323. They all weigh between 223-225 grains. Heavier than I was thinking, but usable. They slide right out of the one piece mold. I am not really sure what the alloy is. It is some that I have had for YEARS. Long ago I worked at a auto salvage yard and made SCUBA weights from wheel weights and other lead I scrounged up. I also have some remnants of who knows what kind of lead my dad collected for casting slingshot balls. (He could hit pop cans at 50 feet on a regular basis with a sling shot. Sure do miss him!!)

I pushed a boolit into the neck of a fired case, just by hand, then chambered it. When I extracted the case, the boolit was left in the throat. I was going to push it back out the breech, but then I figured, I would push it out the muzzle. This way I could see how the rifling engraved it. So I used my wood rod and little wood mallet to push it through. Did not take much effort at all to push it through. The rifling engraved evenly, but the grooves did not touch the body of the boolit except at the base where the rod expanded the base. Now the base of the boolit measures .326, just like the original slug.

That is where I am now. With a few new questions.

1) Will the power coat make up the 0.003 difference between the as cast diameter and the groove diameter of the barrel?

2) Does anyone cast boolits with a gas check already attached?. As in, put a hole in the base of gas check, put the GC into the mold, then pour the lead?

3) Am I on the right track here? As I mentioned the journey is as important to me as the destination. I know I could buy a mold, but while I like to shoot, I also like to make things.

4) The design is simple, do you see any fatal flaws?


Thanks,

John

[JonB_in_Glencoe]

2) Does anyone cast boolits with a gas check already attached?. As in, put a hole in the base of gas check, put the GC into the mold, then pour the lead?

Harvey Prot-X-bore

scroll half way down this chapter for photo and more info
http://www.lasc.us/Fryxell_Book_Chapter_10_GCkorPB.htm

more info
http://hawkbullets.com/prot-x-bore.html

[hemmjo]

wow, lots of good info on that http://www.lasc.us/Fryxell_Book_Contents.htm site.