Seating 308 with 175gr SMK HPBT

[Simplesam]

Hi guys

I recently got a Forster Co-Ax press and im now trying to set up my dies. I have a Forster bench rest bullet seater and in the instructions it says:

7. Place a sample cartridge (setup round) of the correct length in
the shell holder of your press.
8. Raise the shell holder to its highest position by pulling the
press handle completely.
9. Screw the Bullet Seating Stem down until it contacts the bullet
of your "setup round".

However I am new to this game and I do not have a "setup round". How do I go about setting my die correctly to start seating bullets?

Any tips or suggestions?
Sam

 

[Trinimon]

Back the bullet seating stem out all the way 'cept for a few threads.
Set the bullet in the case in the press and raise the ram all the way.
Screw down the bullet seating stem until it touches the bullet.
Lower the ram and screw down the seating stem a few turns.
Raise the ram to seat the bullet. Measure your OAL.
Repeat until you get the OAL you want.
Set that template ammo aside.

 

[Simplesam]

If i were to measure the length of the cartridge after seating with a Hornady Lock N Load comparator (seems the OAL varies with each bullet) what # should i be getting? OAL Max should be 2.8"? And what do people mean when something is x.xx off the lands?

 

[Pr589]

Looks like you are reloading for 308. Regarding the max OAL, treat this as a recommendation rather than a rule. 2.8" is the SAAMI specification that will chamber in all in-spec rifles. The "max" OAL will vary depending on the rifle and the length of its throat/leade.

When someone says x-thousandths off the lands, they have measured the OAL where the bullet touches the rifling of the barrel and they then seat to x-thousandths shorter than this. There are various ways to measure distance-to-the-lands but try Googling and come back here if you have more questions.

Regarding OAL varying from round-to-round, if you're using a comparator differences in bullet tip shouldn't be the issue. How much variance are you seeing? Some possible causes are:
- not hitting TDC when seating
- compressed load and low neck tension (bullet being pushed out)
- seater stem contacting bullet tip rather than the ogive (happens with plastic tipped bullets, and other pointy rounds)
- dirt/grit on shell holder or bottom of case

 

[Trinimon]

If i were to measure the length of the cartridge after seating with a Hornady Lock N Load comparator (seems the OAL varies with each bullet) what # should i be getting? OAL Max should be 2.8"? And what do people mean when something is x.xx off the lands?

The 2.8" OAL (SAAMI max is 2.81") spec will ensure that it will fit in a standard sized 308 magazine.

Your bullet comparator gauge is measuring the length to the OGIVE (CBTO) not OAL. There is some variance in a batch of bullets and the OGIVE measurements will vary slightly from one bullet to another. You can check this by grabbing a handfull of your fav pills and measuring them.

You are getting mixed CBTO measurements because your bullet seating die does not seat via the bullet's OGIVE near the shoulder. Like most bullet seating dies, they seat the bullets just below the tip.

There are a couple ways to check the length of the leade in your barrel. One of them is using a tool like the Hornady LNL OAL Gauge. It measures the max CBTO length where the bullet hits the lands of the barrel. Once you have that measurement, you can seat the bullet just shy of it. Some folks have gained some accuracy from doing this, some did not notice any gains. The nice thing about reloading is that you can experiement.