Bullet Seating Depth

[Mikecr]

There is a misconception here about bearing to base comparison -vs- seated distance to lands(DTL). They have nothing to do with each other..
Even ogive radius variance rarely affects DTL. This affects only meplat diameters per nose length.

The big hitters in seating variance is a poor fitting stem, and high/inconsistent seating forces.
I do not agree with Boomtube about seating variance as less important. best/worst seated DTL is the single largest affect to accuracy. There is a point that is best and the window is not always broad.
But anyone should be able to seat bullets to well within 1thou.

 

[260VLD]

There is a misconception here about bearing to base comparison -vs- seated distance to lands(DTL). They have nothing to do with each other..
Even ogive radius variance rarely affects DTL. This affects only meplat diameters per nose length.

The big hitters in seating variance is a poor fitting stem, and high/inconsistent seating forces.
I do not agree with Boomtube about seating variance as less important. best/worst seated DTL is the single largest affect to accuracy. There is a point that is best and the window is not always broad.
But anyone should be able to seat bullets to well within 1thou.

Mike , fully agree , get that variance down to as little as possible.But sometimes I do wonder if we get too clever for ourselves. Some time back I did a little test , I grabbed a hand full of 155 Nosler CC and a hand full of 155 Sierras 2155 and mixed them together , loaded them up and did not worry about the seating depth , just set the seater to around the mark and did not check the depth with the Redding and stuck them in my ammo box. We shot at 500 yards that day , so every time I shot I did not know which projectile was being shot.
Well , I dropped a point or two BUT not because of the ammo , poor shot release on my part , vertical was good with the mixture of projectiles. BUT having said that , I would not do that for 1K matches. The purpose of the exercise was to satisfy my curiosity about some rumours that the 155 Noslers had more vertical than the Sierras , my conclusion was that both of these projectiles were length tolerant.
In fact the 155 Sierra 2155 has the reputation for being a length tolerant projectile.
And a buddy of mine conducted a similar test in which he loaded 155 Sierras and seated each projectile with a different seating depth , the range was approx 20 thou.
The result was that the 155 Sierra is indeed a length tolerant bullet , I have jumped them from 0 to 80 thou off and it was not until they were over 80 thou that the groups opened up.
So the single best thing one can do is find out what your barrel likes as they are all different !

regards
Mike.

 

[Mikecr]

You don't have to look far to see people reaching great success in development with fine seating adjustments. This, even including those adjustments past touching(into lands).