Help with setting up a full-length sizing die

[cbacejr]

Hi,

I have a Redding 300 Win Mag FL G4 sizing die and I am trying to set it up the .0020 bump back on my Rock Chucker press. I installed the die in the press with a small amount of cam over. I have the standard shell holder and Redding’s comp shell holder set.

I have about 50 cases that have been fired in my rifle. The first thing I did is measured all the cases with my Hornaday Lock-n-load headspace comp and Innovative Technologies headspace gages. The results I received were:

Hornaday Innovative
2.2870 0.0000 Stiff bolt close
To
2.2840 -0.0030 moderate bolt close

Most were 2.2450 and 0.0015

I installed the Redding shell holder ran a few cases and measured them:

Shell holder Hornaday Innovative
+10 2.2795 -0.0070
+8 2.2760 -0.0100
+6 2.2750 -0.0115
Standard 2.2700 -0.0160
New Case 2.6250 -0.0240

I think I’m looking for about Hornaday 2.2820 and Innovative -0.0050.

What am I doing wrong?

 

[Coyotefurharvester]

The die is screwed in too far in the press, back out die. Die adjustment using bolt close effort, the bolt must be stripped. The 300 wm headspace off the belt, so be careful sizing off the shoulder to avoid case separation issues. Most of your cases(from your measurements) are not fully formed to the chamber and likely only need necked sized. Cam over with Redding fl die typically is max sizing(datum length is shortest).

 

[Dufas]

" .0020 bump back" never get there consistently. I hate to hear of people 'camming' over the press. "taking the slop out" - nope, just distorting any bearing surfaces in the press. Oil film thickness is easily 100 microns, case lube thickness is easily 100 x that. Add some brass springback - opps.

 

[Kracken McGraw]

Sounds like the die is too long to me.

 

[Mulligan]

Will a fired case that has not been altered chamber in the rifle?

Many times, a once fired case does not expand enough to warrant pushing the shoulders back. It just has not been fully formed to the chamber yet.

CW

 

[Webster]

" .0020 bump back" never get there consistently. I hate to hear of people 'camming' over the press. "taking the slop out" - nope, just distorting any bearing surfaces in the press. Oil film thickness is easily 100 microns, case lube thickness is easily 100 x that. Add some brass springback - opps.

Cam over should have nothing to do with properly adjusting the dies. Don't understand the spread you get in numbers. If you can easily chamber a fired round, it doesn't need the shoulder pushed back. Back off the die a little so you don't get shoulder bump but the body and neck still get sized. Only after you get a little resistance rechambering a fired round adjust the die for 0.002: bump. Don't shoot hot loads.

Sorry if I am repeating what others have said.

 

[El Matador]

For the best feel when chambering empty brass you should disassemble the bolt. That way the only resistance you feel is with the brass and not the firing pin spring.

It sounds like maybe your chamber is a few thousandths too deep, or the die is too short. I'm a believer in having a firm cam-over for consistent sizing because it takes all the spring out of the press. Without cam-over the press could be flexing more on some brass than on others. I think you have the right idea using different shell holders but it sounds like you don't have one that's just right. Try putting some masking tape on top of a shell holder and trimming it with a razor blade. Just the top "bearing surface" should have tape on it when you're done. Most tape is around 0.005" so if you put it on your Redding +8 you should be pretty close to the 2.282" you're looking for.