Trim Die Problem

dtknowles

Anyone ever have a problem using RCBS File Trim Die with Lyman shell holder. I got a new rifle in .243 Win. picked up some Lachmiller dies and an RCBS File Trim Die. Those Lachmiller dies looks awesome, coolest looking dies I own. The RCBS File Trim die looks like others I have but when I used it the cases were still longer than max. allowable case length. I did not check the cases after trimming the first time and I had high pressure signs with low to moderate powder charges and I started checking things out. My once fired cases are right at max. 2.045 and when size in the trim die are in the 2.047-8 range. I have not be in the habit of checking length every discharge so after a couple cycles they were way too long and causing high pressures. I just loaded another box for testing and these I trimmed with a 0.005 inch shim under the case which got the cases trimmed to 2.042-3 inch range. I can think of only a couple explanations,either the trim die is defective or my Lyman shell holder is incompatible with the die. I am not comfortable with the shim because I am concerned that I am pushing the shoulder back too much. Any ideas.

Thanks
Tim

788-308

Check the distance from the top surface of the shell holder down to the surface that the case head contacts. Should be .125". That is the dimension that RCBS dies are machined for.

Tailgunner1954

Size your brass before placing it into the trim die.
Set the die so that it contacts the shell holder.
If you need to trim off more of the neck, than either remove material from the bottom of the die, or easier (and cheaper) is to remove material from the top of the shell holder, until your trimmed length is correct.

The Lachmullers seaters are cool, they will do any cartridge that uses that diameter of bullet (The RCBS Precision seaters work on the same principal as the Lachmullers)