Problem case trimming the 450 Marlin

[NYDAN]

When I ordered the case trimmer pilot for the RCBS manual case trimmer I ordered the 45 RIFLE pilot for .458 bullets. However, it isn't working. It is too tight.

The I.D. of the case mouth of my resized brass is about .450". The O.D. of the pilot is about .452".

The RCBS instructions are very clear that the cases are to be trimmed before expanding the mouth.

Should I have ordered the 45 caliber PISTOL pilot for .452" bullets? If so, how was I supposed to know that?

 

[JD338]

Dan,

The 450 Marlin is .458" Cal. Maybe slightly bell the case mouth.

JD338

 

[truck driver]

I always size my cases and expand the necks before trimming.
I guess I never read the directions :roll:

 

[NYDAN]

Dan,

The 450 Marlin is .458" Cal. Maybe slightly bell the case mouth.

JD338

That works! I backed the expander way out and inserted the end just a little. It opened up the mouth just enough for the pilot. It adds another step and I will have to re-set the expander die every time I use it.

I used some Imperial dry lube. Do you normally use a lubricant to expand the case mouth on these straight walled cases? I don't remember doing that with the .357 mag. I loaded 35 years ago.