Bullet seating depth

[The Oregonian]

New to reloading here...have a factory A-bolt in 270 win and working thru my first batch of brass to load up, then will work on load development.

As far as seating depth, Nosler (using 150gr ABLR and 130gr B-Tip, as well as Nosler brass) specifies COAL in their manual. But in development I will want to play with seating depth to see how it reacts to COAL.

How do I know how far the bullet is from the lands? Or is there a way to test with cartridges (i.e. load a bullet into brass without much tension and close bolt, or something to that effect - but that may get a bullet stuck in the lands).

Thx

 

[Mikecr]

There a various methods(many threads here) for determining max cartridge base to ogive(CBTO), but I doubt you'll reach it in a factory A-Bolt.
You could go straight to Berger's seating testing at minus 2% from book max load, with careful measurement and logging of best CBTO. And of course watch for any pressure 'issues' with seating further out..

Max COAL, and/or distance to lands(DTL), are just descriptive terms.
All that really matters is most accurate local CBTO. Go ahead and find that first, and twiddle around with determining DTL, if desired, later.

A simple tool for measuring CBTO that works well, is a Sinclair 'nut':
SINCLAIR HEX STYLE BULLET COMPARATORS | Sinclair Intl
This is a better measure than COAL, and it pays down the road to always use the same tool so that you can always replicate logged dimensions(even with different bullets).

 

[FearNoWind]

With a bit of searching you'll find a lot of good (and some not so good) information about bullet seating depth in this and other forums.

Mikecr's advice to rely on CBTO is, IMO, perhaps the most important factor in learning how to manage seating depth.

The SINCLAIR HEX STYLE BULLET COMPARATORS | Sinclair Intl and a good caliper will do the job.

This tool:

Hornady Lock-N-Load Overall Length Gage Bolt Action
can help

These tools:

Hornady Lock-N-Load Bullet Comparator Body

Hornady Lock-N-Load Bullet Comparator Complete Set 14 Inserts

and a good digital caliper can also make things somewhat easier.