bpost1958
07-18-2010, 08:16 PM
I have been using this mold for 30 years and have seen the void hundreds of times, at 25 yards it does not matter. At fifty yards it is a group wrecker. The mold is a tad tired but still tight, venting in the blocks is fine, 95% of the boolits are fine, it is the 5% that has me worried.
For some reason this boolit style can create a void in the base on some small percentage of casts. Some look like little pin pricks near the sprue, some are a tell-tale indentation on the outer edge of the cast, near the edge of the boolit. All of them are larger cavities than meet the eye.
There is little evidence of the deeper voids until the boolit is fired. These voids MUST (and do) upset the flight. I discovered four tonight that LOOKED absolutely perfect but the air pressurized under the boolit during sizing indented the small void present. Lachmiller sizer 460 top punch Alox/beeswax .452 sizer.
After painstaking care today, in 90 degrees plus heat and high humidity, I cast 20 pounds of them for an upcoming 2700 Match in VA.
The issue is NOT pull out or mold venting. The pour rate was varied from a heavy flow to a trickle from an RCBS pro-melt. The void, once you know what to look for can be confirmed by a dental pick. The void is USUALLY oval in shape varying from almost the size of a period(.) to as large as 1/64th X 1/8th in length. The formation is RANDOM with no discernible pattern. Fifty Boolts may be fine and the void develop in six out of the next ten boolits cast.
Please note, the alloy does NOT matter in the formation of the void. The MOLD used does not matter, it is the Boolit, the base specifically that has the "issue". Other shooters, picking up range lead have noted this dimple too. It is not an isolated case. The Lyman 452460 Mold shape is the common denominator. I also have a Lee 200 SWC bevel base six cavity mold. That mold does not exhibit this trait.
What do you think is causing this void????
Another question; why are boolits poured base up? One would think the base is the most critical part and therefore be on the bottom where perfection of shape is almost guaranteed.
For some reason this boolit style can create a void in the base on some small percentage of casts. Some look like little pin pricks near the sprue, some are a tell-tale indentation on the outer edge of the cast, near the edge of the boolit. All of them are larger cavities than meet the eye.
There is little evidence of the deeper voids until the boolit is fired. These voids MUST (and do) upset the flight. I discovered four tonight that LOOKED absolutely perfect but the air pressurized under the boolit during sizing indented the small void present. Lachmiller sizer 460 top punch Alox/beeswax .452 sizer.
After painstaking care today, in 90 degrees plus heat and high humidity, I cast 20 pounds of them for an upcoming 2700 Match in VA.
The issue is NOT pull out or mold venting. The pour rate was varied from a heavy flow to a trickle from an RCBS pro-melt. The void, once you know what to look for can be confirmed by a dental pick. The void is USUALLY oval in shape varying from almost the size of a period(.) to as large as 1/64th X 1/8th in length. The formation is RANDOM with no discernible pattern. Fifty Boolts may be fine and the void develop in six out of the next ten boolits cast.
Please note, the alloy does NOT matter in the formation of the void. The MOLD used does not matter, it is the Boolit, the base specifically that has the "issue". Other shooters, picking up range lead have noted this dimple too. It is not an isolated case. The Lyman 452460 Mold shape is the common denominator. I also have a Lee 200 SWC bevel base six cavity mold. That mold does not exhibit this trait.
What do you think is causing this void????
Another question; why are boolits poured base up? One would think the base is the most critical part and therefore be on the bottom where perfection of shape is almost guaranteed.