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AR15Barrels
This is what I posted.
Dave
When you started your testing you should have seated your bullets as long as is possible for your particular set-up.This allows you to find your accuracy node and eliminates the possibility of seating depth based pressure signs.
If you re-read it it says as long as possible for your particular set-up and nothing at all about touching the lands or going into the lands.
On a "Ladder Test" it is always best to seat as long as the set-up will allow and not have to worry about pressure or were you started from down the road.
In this example he would start at whatever length he felt comfortable with in his magazine and after finding his powder charge he could simply seat deeper until best accuracy was achieved.
Seating depth works like several hour glasses stacked end to end.His groups will shrink and expand several times as he continues to seat deeper and deeper.
I have never seen nor heard of a gun that the seating depth has no influence on accuracy.
BLR81
Seating the bullet long increases the space in the cartridge and therefore decreases pressure and velocity over stated load data. On the other hand seating into the lands creates a higher pressure not experienced when seated .020" short of the lands which can lower your max stated load data considerably.
Seating depth variation into and out of the lands will change the pressure 3000-4000 psi and that is why it is best to start as long as is possible and work in one direction only.When the bullet is just touching the lands or slightly into the lands the pressure increases modestly because there is no headstart or smooth transition.The engraving forces require the pressure to build up before they can overcome the necks tension and the engraving into the lands both.
If your working up a load it makes little sense to start somewhere that will negate all your testing because of a simple seating depth change.If you start out with the bullets seated as long as they will ever be seated you won't have to reduce your charges when changing your seating depth.
It doesn't matter what you load for benchrest or hunting you should always start out as long as YOUR PARTICULAR ROUNDS WILL EVER BE SEATED.That could be 0.050 into the lands or 0.125 off of the lands.
This is what I posted.
Dave
When you started your testing you should have seated your bullets as long as is possible for your particular set-up.This allows you to find your accuracy node and eliminates the possibility of seating depth based pressure signs.
If you re-read it it says as long as possible for your particular set-up and nothing at all about touching the lands or going into the lands.
On a "Ladder Test" it is always best to seat as long as the set-up will allow and not have to worry about pressure or were you started from down the road.
In this example he would start at whatever length he felt comfortable with in his magazine and after finding his powder charge he could simply seat deeper until best accuracy was achieved.
Seating depth works like several hour glasses stacked end to end.His groups will shrink and expand several times as he continues to seat deeper and deeper.
I have never seen nor heard of a gun that the seating depth has no influence on accuracy.
BLR81
Seating the bullet long increases the space in the cartridge and therefore decreases pressure and velocity over stated load data. On the other hand seating into the lands creates a higher pressure not experienced when seated .020" short of the lands which can lower your max stated load data considerably.
Seating depth variation into and out of the lands will change the pressure 3000-4000 psi and that is why it is best to start as long as is possible and work in one direction only.When the bullet is just touching the lands or slightly into the lands the pressure increases modestly because there is no headstart or smooth transition.The engraving forces require the pressure to build up before they can overcome the necks tension and the engraving into the lands both.
If your working up a load it makes little sense to start somewhere that will negate all your testing because of a simple seating depth change.If you start out with the bullets seated as long as they will ever be seated you won't have to reduce your charges when changing your seating depth.
It doesn't matter what you load for benchrest or hunting you should always start out as long as YOUR PARTICULAR ROUNDS WILL EVER BE SEATED.That could be 0.050 into the lands or 0.125 off of the lands.
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