Reducing weight variation

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  • Last Post 26 March 2016
donr308 posted this 26 March 2016

Recently I cast a large quantity bullets using a Lee 6 cavity mold for the 45 cal., 230 grain TC bullet. When I started weighing the to get an idea of how uniform they were I was disappointed to find that extreme variation was nearly 5 gr. or 228.7 to 233. Some of the heavier bullets appeared to have a mold parting line on them. I cast another batch and changed routine by after closing the blocks I lightly tapped the the mold on one side at the junction of mold and handle. It helped some but I was still not satisfied. Searching for a solution I remembered the locking mold handles from Cabin Tree that I purchased about 5 years ago and seldom used anymore. I did not know if the 6 cavity mold would even fit. It did and I then cast a small batch of 329 bullets and weighed all with an electronic scale. I rejected 14 that weighed less than 228 gr. 265,or 80.5%,  weighed between 228.1 and 229.1 gr. (228.6 plus or minus 0.5 gr.) and 299 weighed between 228.1 and 229.5. or 95%. The locking mold handle definitely made a significant difference. Cabin Tree's web site says they have sold that part of the business to this company http://cowboybullets.com/ . They are now made of aluminum which should ease the load on the wrist. The blow photo is of the mold blocks on the handles and 2 targets recently shot at 50 yards with weighed bullets and Marlin lever gun rechambered to 45 ACP. Very gusty wind. The 10 ring is 1.75". Don     

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Larry Gibson posted this 26 March 2016

When using the Lee 6 cavity moulds with the Lee handles It is almost natural to hold onto the sprue plate handle when pouring. Doing that puts a little pressure on the mould block by the cam of the sprue plate handle. That slightly opens the bottom of the blocks creating the “mould parting line” on the bullets and giving a larger than normal weight variation.

When closing the sprue plate on closed mould blocks I slightly pivot the sprue plate handle back out.....just a bit, not enough to move the sprue plate. That ensures there is no cam pressure on the mould block. I also am careful to just use the mould block handles keeping the blocks together when pouring. Not to hard to get used to doing.

The Cabin Tree handle lock certainly solves the problem but so does using the Lee handles correctly. Like most I learned the correct way the hard way.......

LMG

Concealment is not cover.........

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OU812 posted this 26 March 2016

Verygood shooting using 45 acp.

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donr308 posted this 26 March 2016

Thanks for the comments. My usual MO with 6 cavity Lees are almost identical to yours. I have 6 of them and have had very satisfactory results for years. One thing I don't do is pull the sprue plate slightly back from the block. As far as touching the sprue plate handle I found it difficult to attempt to do in a regular casting position. I use a RCBS bottom pour pot with the built in mold guide and the operating handle on the right side. What prompted the project was the excellent accuracy I was getting with this rifle and wanted to see how far I could go. The few 100 yd. groups I've attempted have gone as small as 2". One side benefit is I put a mil dot scope on it for test purposes and found that with a 50 yd. zero the 2nd mil dot down is dead on at a hundred yds. Some shooters at my club put clay birds on the 100 yd. berm. I been shooting at and hitting the larger broken pieces. It's not a ground hog rifle, yet.  Don  

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