Casting Problems

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Joined: Wed Apr 30, 2008 7:03 pm

Casting Problems

Post by 45idaho » Wed Apr 30, 2008 9:33 pm

Yesterday I fired up my Lee bottom pour pot and made several hundred bullets with 4 different molds. It has been over a year since I have done any casting. The molds were a Lee 6 cavity 452-255-RF, a 3 cavity alumimum Mountain Mold 250 grain .452 bullet, a steel 2 cavity Lyman #452651 mold, and a 2 cavity .452 325 grain Mountain Mold. All were cast with WW at 700 degrees and water quenched. The bullets from the steel Lyman molds had far less rejects than all the aluminum molds. The majority of defects from the aluminum molds was a little wrinkle on one side of the bullet where the 2 halves of the mold (vent) close. I did not clean the molds before I started casting because they all looked in perfect shape. There must have been some kind of contamination on the alumimum molds or a venting blockage. In all cases it was only on one side and the problem did not seem to get better or worse after the molds were up to temperature and a lot of lead was run through them.

Is this normally caused by contamination on one side of the mold, a mold closure problem, plugged vents, or all of the above? How do you recommend cleaning and inspecting the molds before casting?

I hate the old steel Lyman 452651 mold. It always casts great looking bullets with very few rejects, but they are oblong (.450 to .454). I don't like the 2 crimp grooves, but they always seem to shoot good. It must be a lot of bearing surface and a small (70 percent) meplat. The Lee 6 cavity will crank out a bunch of bullets in a hurry, but they are undersize. Both Mountain Molds are prefectly round and come out within .001 inches of what I ordered them.

My hunting bullets were always the Lee C452-300-RF and the Lyman 452651 cast with water quenched WW. The Lee with WW is about 320 grains and the Lyman comes out about 340 grains. The Lee has about an 80 percent meplat and always did a lot more damage to the deer and elk I have shot than the Lyman with about a 70 percent meplat. I have never found a bullet, even in elk with a quartering shot. The Lyman always seems to group a little better than the Lee, even though it comes out oblong. I think that is because of the smaller meplat and longer bearing surface of the Lyman. The problem with the Lee is the 2 small crimp grooves (the Lymans are bigger). I had a hell of a time keeping the Lee from jumping crimp. On both bullets I only use the rear crimp groove. If your cylinder is short enough that you need the front one on either bullet, you should shoot a shorter bullet.

After fighting oblong bullets and small crimp grooves, I decided to design the "perfet bullet" with my "wealth of knowledge" from the bullets so familiar to me and the Mountain Mold website. I now cast a bullet that has a generous crimp groove in the right place and a huge 80% meplat. It has worked flawlessly on 2 elk, 3 deer, and a black bear. Even though I can't get it to group quite as tight as the oblong Lyman, it is the only bullet I take hunting (and proud that I had a small part of desiging it).

Thanks Dan, for all the info in your website! You saved me a lot of grief and instructed me enough to design a bullet that fits perfectly and would have a "hell of a time" making it better. After a couple of years shooting this bullet, the only thing I might change to is a Truncated Cone vs an ogive. With your help, I got it right the first time!

Sorry I got so far off the subject! Can you give me some pointers on the little wrinkle on the side of my bullets?

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Re: Casting Problems

Post by mtngun » Thu May 01, 2008 5:50 am

Thank you for the detailed report.

I've never had any luck giving long-distance casting advice.

My aluminum and brass molds are shipped ready-to-cast. They do not need additional cleaning.

Wrinkles usually mean something is too cold.

Don't get me started on Lee bottom pour pots. :P

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