from 1967 Gun Digest 21st Edition p. 74 -=-=-=-=-=-=-=-=-=- BULLET MOULD CONDITIONING by Gene B. Crum A new and far faster method of breaking-in moulds is now available - with obeisance to du Pont, it's through chemistry! Today's bullet moulds represent the sum of extensive experience on the part of American shooters and the best material and production know-how on the part of manufacturers; nevertheless, shooters have discovered that no matter how advance the mould manufacturing process, no matter how high the equality, it is still necessary to spend some time "breaking in" moulds for best results. Common practice has been to wet a rag with a solvent such as carbon tetrachloride, wipe the mould blocks clean of preservatives, and then cast up to several hundred bullets purely for breaking in purposes. these bullets usually are returned to the pot, since they are frequently defective. CHEMICAL CONDITIONING It is no longer necessary to follow this practice. A simple chemical treatment can make mould blocks produce acceptable bullets, starting with the second bullet cast! This chemical process was worked out after consideration of these factors: mould blocks are routinely heated-treated at the factory during manufacture; prior to packing, the blocks are covered with a penetrating preservative oil; oil in a mould cavity will produce defective bullets. Since the blocks are heat-treated under controlled conditions, any further curing while casting must be minor, for it is to the manufacturer's advantage to control all variants which might produce inferior blocks and he has the equipment to do this. If, therefore, home curing produces only negligible improvements, the inferior bullets made during the breaking-in process must be caused by other than substandard curing. Oil in the mould cavity is the chief causes of faulty bullets. If the caster has merely scrubbed his new blocks with a solvent-soaked rag, then the blocks are still fouled with oil. This results from the penetrating quality of the preservative oil and the porous nature of the malleable iron blocks. While wiping with a rag removes surface oil and imparts a "dry" feeling, the blocks are actually sodden with oil which has entered the pores of the metal. The sudden heat of molten lead entering the mould cavity causes this oil to partly vaporize and enter the cavity, spoiling the bullet. As the bullet cools, some of the oil returns to approximately its original form, re-enters the pores of the block and waits to be re-liberated by the next cast. --- ß SLMR 2.1a ß NRA Endowment Member..Sumner,IA vmwilson@combatarms.com --- GOMail v2.0 [94-0419] * Origin: Combat Arms BBS - Portland, OR - (503) 221-1777 (1:105/68) 0SEEN-BY: 105/50 68 360 376/206 396/1 3615/50 51 3634/2 38 300 Oil in t0PATH: 105/68 50 3615/50 3634/38 From: VICTOR WILSON #0 @1:105/68 via 1:3634/38 FIDOnet Re: Info #2 of 3 0AREA:RELOAD 0EID:A8AC 819892A0 In time, most of the oil will be evaporated from the mould. Sometimes, if the preliminary cleaning was very casual, oil will be left in the mould after hundreds of bullets are cast. When this happens, the mould will not cast a perfect bullet and is usually condemned as a "lemon." This is an unnecessary attitude, because even such moulds may be reclaimed to a certain extent. CLEAN WITH CHLOROFORM To remove oil from the mould pores, the blocks should be completely disassembled, cleaned according to custom and then soaked in chloroform for two hours in a covered glass vessel. Next the blocks should be removed and immediately flushed repeatedly with hexane, a fraction of petroleum ether. The chloroform soaking penetrates the pores of the metal and draws out the oil, while the hexane flushings remove the residue of the chloroform-oil mixture. The hexane flushings are absolutely necessary, and the chloroform soakings should not extend for more than two hours. Reassemble the blocks and cast several bullets. Every bullet, starting with the second or third, should be useable. To bring the mould to casting temperature quickly, alloy the first several bullets to cool in t he mould for a few minutes before removal. PRECAUTIONS Several precautions should be observed: after concluding this oil- removal process, the blocks are completely unprotected and are very prone to rusting. It is beneficial to rub them with a silicone cloth before and after casting, and to seal them in an airtight container (ideally, with a desiccant, such as is packed with photographic film) between uses. Under no conditions should the blocks be stored with a bullet still in the cavity, as is the custom in some circles. It was learned during experimentataion that prolonged soaking of the blocks in the chloroform impaired casting qualities. two hours represents maximum time, and about one hour is minimum. Much depends on the amount of oil removed during preliminary cleaning operations. If free oil remains on the metal's surface, the chloroform's solvent qualities will quickly become exhausted, necessitating a fresh chloroform bath. --- ß SLMR 2.1a ß NRA Endowment Member..Sumner,IA vmwilson@combatarms.com --- GOMail v2.0 [94-0419] * Origin: Combat Arms BBS - Portland, OR - (503) 221-1777 (1:105/68) 0SEEN-BY: 105/50 68 360 376/206 396/1 3615/50 51 3634/2 38 300 0PATH: 105/68 50 3615/50 3634/38 From: VICTOR WILSON #0 @1:105/68 via 1:3634/38 FIDOnet Re: Info #3 of 3 0AREA:RELOAD 0EID:5C86 819892A0 When this process is used on "lemon" moulds, the percentage of defective bullets cast will be greatly reduced. The moulds might still cast some defective bullets, however. It is the user's decision whether it is economically wiser to purchase a new set of blocks. Chloroform should be used only in a well-ventilated area. It is not flammable or explosive, but continued inhalation is dangerous and could be fatal. Chloroform should not be stored around the home. Hexane, a fraction of petroleum ether, is highly flammable. All precautions applying to the use and storage of gasoline should be applied to hexane, including the warning to avoid inhalation and to work in a well-ventilated or outdoor area. It is generally wiser to dispose of unused hexane than to store it around the house for future use. Technical or high grades of chloroform and hexane are available at most drug and chemical supply houses. Nearly every chemical laboratory will have these two common chemicals on hand. For one set of single- or double-cavity mould blocks, one quart of chloroform and one pint of hexane should be sufficient, with enough material left over for a retreatment if such a step is necessary. Used chemicals should be discarded and not reused; they have served their purpose and are waste. Consult the source of the chemicals for the accepted disposal methods in your community. NOTE: It would likely be smart to check about the availability of the above mentioned chemicals in the 1995 era before getting too excited about trying the methods explained in the article. ..........END OF FILE..........