Rcbs lamii

[donald duck]

Just purchased an RCBS Bullet sizer. Want to size cast bullets from old Lyman Ideal Mold 120 grain Gas Check. What should I size my bullets?? I have been using a Lee .285 and accuracy is fine in 7 X 57, 7-30 Waters, 7 MM TCU, and 7MM WSM. What top punch?? Bullet lubes?????? Have been dipping my cast bullets with GC in a sardine can with beeswax, candle wax and it works fine. The Lee put too much wax on point of bullet and after 20 or so rounds waxed up my Bullet seating die. Hope the RCBS gives me a cleaner bullet. All Ideas appreciated!! Love to read all your comments. dd

[Mk42gunner]

At a guess, I would start with a .285" die. The top punch can be found by looking up your mold numberon castpics.net, then ordering a new one.

The best way is to slug your barrels to find out what diameter is needed.

Robert

[Von Gruff]

If .285 has been working in the Lee then it follows that a .285 would be the best place to start in the RCGS as well, especially as you have been getting good results with .285 to date. It sound like you are more in need of a change in sizing method rather than size.
I have the same set-up (although my sizer is a Lyman 450) and have lapped the Lyman to .2855 and the Lee to .285. Everything goes through the Lyman at .2855 for a start but I found that when I get past 1900fps with a 50/50 and an Al GC, my rifle prefers a ahrder alloy with a Cu GC and sized to .285 through the Lee.
A bore slug, as mentioned, is a good place to start but nothing replaces testing the differences.

Von Gruff.