Micrometer Seater useful?

[cape cove]

It most certainly will. One of the advantages of the Lee seater is you can remove the seater stem and use it along with your vernier to measure the CBTO

 

[lancetkenyon]

Not arguing here. Just a question. Should sorting the bullets by measuring from the base to the ogive help in this regard?

It would. But what are you going to do with the ones you deemed "out of spec"?

 

[lancetkenyon]

It most certainly will. One of the advantages of the Lee seater is you can remove the seater stem and use it along with your vernier to measure the CBTO

But seating stems do not seat off the ogive. They seat down from the point. And if your BTO varies, it is not giving you a true measurement from the ogive which is where the bullet contacts the lands.

In all honesty, the Hornady or Wilson comparators don't quite measure from the ogive, but very close. Much more so than measuring with a seating stem.

 

[cape cove]

The #'s I get when using the Lee stem are more constant from round to round that when I use my Hornady CBTO tool. I guess you could say the # is more of an OAL than a CBTO.

 

[Mikecr]

Should sorting the bullets by measuring from the base to the ogive help in this regard?

No, it won't.
Base to ogive (BTO) is base length + bearing length + high ogive datum.
The only part of this related to CBTO is ogive datum, as affected by ogive radius.
Seating stems do contact ogives (the ogive is the entire bullet nose), pushing at their own datum.
That stem datum is then affected by ogive radius, and there is a measure for this that helps with consistent seating:
It's a Bob Green Comparator (BGC).

Seating stems contact low on ogives for the steepest angle to push against. An angle too shallow (higher on the ogive) would wedge too much.
There is 'some' wedging anyway which varies with seating force, and this is reduced through stem bedding.
But consistent and moderate to light seating force leads to less seating variance.

I qualify ogives with a BGC, match pre-seating forces with an instrumented mandrel die, and my stems are bedded to specific bullet.
I always measure CBTO, with every round, and it's rare that I need to go back and adjust the micrometer with re-seating.

 

[MagnumManiac]

That stem datum is then affected by ogive radius, and there is a measure for this that helps with consistent seating:

This is one of the MOST IMPORTANT aspects of consistent seating and distance to lands affecting outcomes.
This is why we bed our stems for ONE bullet in ELR, of course sorting ogives precisely must be done.
As @Mikecr says, ogive variance and measuring LOW on the ogive is key here.

Cheers.

 

[Rflshootr]

When I load, I go about it in a slightly different way. I seat all the bullets .010 long. Then I go back and measure each round with a Sinclair nut gauge, make an adjustment to the micrometer and re-seat each individual round. No time wasted in boring bullet sorting any more. It also removes the chance of putting a bullet in the wrong pile while sorting and having different bags or containers with each length bullet.

 

[MarkInPA]

No, it won't.
Base to ogive (BTO) is base length + bearing length + high ogive datum.
The only part of this related to CBTO is ogive datum, as affected by ogive radius.
Seating stems do contact ogives (the ogive is the entire bullet nose), pushing at their own datum.
That stem datum is then affected by ogive radius, and there is a measure for this that helps with consistent seating:
It's a Bob Green Comparator (BGC).

Seating stems contact low on ogives for the steepest angle to push against. An angle too shallow (higher on the ogive) would wedge too much.
There is 'some' wedging anyway which varies with seating force, and this is reduced through stem bedding.
But consistent and moderate to light seating force leads to less seating variance.

I qualify ogives with a BGC, match pre-seating forces with an instrumented mandrel die, and my stems are bedded to specific bullet.
I always measure CBTO, with every round, and it's rare that I need to go back and adjust the micrometer with re-seating.

Thought maybe people might be interested in the link to this tool. Looks like Bob has it on sale for $250.00.

Bob Green's Rifles

Complete Bench & Varmint Rifles Precision Barrel Installation Superior Custom Dies and Tooling Specializing in craftsmanship

greensrifles.com

 

[nksmfamjp]

I think I get it. If I'm fine with my variation one time through the seater, the micrometer is not required. If I want to seat in 2 steps for perfect oal, the micrometer is required.

That said, how does +/-0 coal compare to +/-0.001 coal on target?