Making Monotype from Super Hard

[detox]

Rotometals sells an alloy called Super Hard (30 percent antimony, 70 percent lead). What percent lead and tin do I need to add to make Monotype

.................Tin.....Antimony...Lead...BHN

Monotype... 9..........19...........72......26

Super Hard..............30...........70.......?

[62chevy]

1.5 pounds of tin and 4.5 pounds of pure lead. But you really need the Alloy Calculator to figure this kind of thing out.

[RogerDat]

Yep the calculator is the thing for this. Can also download Apache Open Office for free to run it if you don't have Microsoft Office. I'm guessing the calculation above was for a 5 lb. ingot of super hard that would yield a 10# pot of Monotype.

Have to ask why would you want to make Monotype? Most of the time I see recipes that call for some Monotype to make something else, not as a goal to use as is so just curious.

[detox]

I will be experimenting at higher rifle velocities:

Tom Gray says:


When I was building and shooting bench rest cast bullet rifles we approached the fitting of tapered bullets to the guns's throat a different way. We used a bump press to taper any cast bullet to fit the tapered throat of the gun. There was an added benefit as by bumping the bullet in a die, the gas check and the base could be made dead square with the centerline of the bullet. The gas check was also very flat on the bottom and the amount of bump force was adjusted to still maintain a small radius at the base edge of the gas check.

Most used one degree included angle tapers on the lands with a short freebore that was around a thousanth of an inch over bore dia.. Some shot bullets up to 4 or 5 thousanths over bore but I didn't subscribe to that practice. I stayed about a thou. over on the straight cylindrical part of the base of the bullet. My idea was not to size the bullet down in the throat of the gun under the tremendous, violent conditions of combustion but to do it under much more controlled conditions in a sizer/lubricator where everything could be controlled and held straight.

I once had some of my bumped bullets checked on an optical comparator (shadow graph) and they were dead square bases to the centerline of the bullet.

I had my 30BR reamers made with the freebore dia. at .0003 to a half thou. over groove. That way they could be used for jacketed bullet guns too. Then I had a throater reamer made to the dia. and taper I used and throated the barrel to that taper after chambering it. Throating was done in a separate operation but in the same machine setup. I would throat the barrel till the bullet seated about 25 thousanths into the case mouth would just push back a little with the bolt was in battery. That way the bullet was pushed snugly up into the taper and didn't jump to the lands. As soon as it moved, the tapered lands started engraving the whole lengty of the nose instantaneously. Marks on the nose of recovered bullets showed no slippage of the bullet in the lands. And very little distortion to the bullet skin.

I also used that same throater reamer to make the bump die. As you can see, it then allows you to make a bullet that is the exact dimensions of the throat for perfect support when it enters the barrel.

Don Eagan used to use the taper of a standard taper reamer for his moulds. It was a little different than a half degree per side. They all worked well but as Ken mentions a half deg. per side gives you a max length of taper and still leave some straight side on the bullet for the match to the freebore. I made the bullets a slight interferance fit to the freebore to get the best seal and support possible of the bullet to throat.

If you're looking to maximize accuracy, you want to concentrate on bullet to throat fit. Most things that happen that at detrimental to cast bullet accuracy happen in the throat of the gun. By making a bump die, almost any bullet could be swaged to match the throat of the gun. This opened the door to a whole lot of bullets to try.

If you search the archives of this list you will find this discussed in detail several times over.


Yes, it's not hard to bump up a bullet in an RCBS Rock Chucker press setup. I've heard that this press can generate ~60,000 psi. when it rolls over center at the top of the stroke. It takes very llittle effort to do it. When trying to bump up, I used to get stretching of the bump dies if they were made of 7/8" stock so, I took the bushing out of the top of the press and used stock that was much larger in diameter. Even Drill Rod would stretch and that's pretty tough stuff. Having a thicker wall on the dies solved the stretching problem.

Bumping lead bullets up is less desirable than sizing them down. It's better not to choose a throat that is over .309" and then everybody's 30 cal. bullets can be made to fit by sizing down. In bumping them up, die stretching and bump force make it very hard to maintain a consistent diameter unless you use a soft alloy and shoot them slow. My bump press design was made in such a way as to control where the taper started on the bullet as well as the bump force when the press rolled over center.

Yes, I used alloys of monotype and Foundry type to shoot in the 2500 to 2700 fps. range. This was to minimize wind drift. These alloys always cast very easily too which added to the consistency of the bullets. With properly sized bullets and my proprietary lube, leading was not existent.

I always figgered that using bumped bullets, match prepped Lapua brass in a 30 BR chamber and a match grade SS barrel, with a Stolle action, Jewel 2 oz. trigger, and a 36 power scope, the guns were capable of .3 MOA. Now, shooting that well in the conditions was another story!!!

Tom

[62chevy]

Yep the calculator is the thing for this. Can also download Apache Open Office for free to run it if you don't have Microsoft Office. I'm guessing the calculation above was for a 5 lb. ingot of super hard that would yield a 10# pot of Monotype.

Have to ask why would you want to make Monotype? Most of the time I see recipes that call for some Monotype to make something else, not as a goal to use as is so just curious.

My bad that was 10 # of Super Hard.

[Cowboy_Dan]

If you plan on making boolits out of straight monotype, you should know that it is very brittle. Brittle enough that chambering a round can crack the boolit, as can dropping it. Just saying, exercise caution.

[RogerDat]

Would think heat treating could put you in the same BHN without the brittle factor. Might also be useful to read up on getting a little copper alloyed into that mono alloy your making.

Good luck! Thanks to this here internet thingy I learn a lot from you folks that go out and push the envelope.

[scottfire1957]

Well, I read it that he (Gray) used mono and foundrytype as the BASIS for his boolit alloys.

I used alloys of monotype and Foundry type to shoot in the 2500 to 2700 fps. range.

Not "I used the alloys monotype and foundry type."

YMMV.

[tygar]

I have hundreds of #s of foundry & mono & never use it since lino is easier to get what I want & what I can't find a lot of is soft so it would be easier mixes.

But..I've dropped plenty of mono & foundry & never broke any. Guess I'll try it just to see if I can break it.

[jhalcott]

I had access to Foundry , monotype and stereotype alloys when I worked. I cast some .44 boolits from them(and a mix of these alloys). At the range I was getting 2(TWO) hits per trigger pull! An OAF at the line dropped one of these rounds on to the cement floor and it BROKE at the crimp line. I got a bit worried about these loads and started to add pure lead and/or WW to them to soften the boolits. Lots of combinations were tried till I got a BHN near Lyman #2 or 15 BHN. BUT, YES very hard alloys CAN break from shock.

[RogerDat]

Especially unpleasant I hear if they break being fed in from the magazine of a bolt action. That disconnect between the projectile still in the brass with the powder and the loose chunk is not exactly great if you pull the trigger.

You can break a bar of Linotype with a hammer, foundry or mono should be even harder and more brittle.

[LAGS]

I am making all of my own Linotype and Monotype from scratch.
Then I use those for resmelting down to softer mixes for the pistols.
I was not aware that 30 % antimony was soluable in lead at that high of percentage that would give you any more hardness than 19 %
But 30% would seem kind of brittle.
But it is a good way to smelt down the Antimony to make it easier to add to other alloys.
Raw Antimony melts at a Higher temperature than Lead or Tin.
So, you have to add the solid pure antimony crystals to melted lead and let it sit cooking for an hour to get it to disolve , sort of like sucking on a piece of hard candy.
Then you can add the tin to your mix.
But once Antimony is disolved into the lead, it will remelt very similar to lead.

[LAGS]

OK ,I did the Math.
You need to add 4.36 Pounds of lead and 1.42 pounds of Tin to 10 pounds of Super hard to make it into Mono Type.