QUICKLOAD Seating Depth

[Albedo]

I finally was able to buy a copy of QUICKLoad to use for an experimental bullet design I have been working on, but they don't exactly describe what they refer to as the seating depth. What exactly is the seating depth and where is it measured from?

My bullet is 0.938in long including it's 0.110in long rebated boattail. The distance from the tip to the end of the knurling on the side of the bullet is 0.53in. Diameter, if it matters is 0.224in. I assumed seating depth would be the distance from the RBT to the knurling, since the bullet will be inserted to that depth. But that doesn't seem quite right.

Also, while I am here, does anybody know about swaging secant ogive bullets? I would like to make this a secant ogive bullet but have only found information on Tangent from Corbins.

Thanks for any help!

 

[Straightshooter1]

I finally was able to buy a copy of QUICKLoad to use for an experimental bullet design I have been working on, but they don't exactly describe what they refer to as the seating depth. What exactly is the seating depth and where is it measured from?

Seating Depth is how far into the case the bottom of the bullet is (note: variance in seating depth varies the volume the case has for powder). QL the Seating Depth is the measurement from the base of the bullet to the rim of the mouth of the case. The Shank Seat. Depth is the measurement from the boat-tail/bearing surface junction to the rim of the mouth of the case (for boat-tail bullets, anyway).

 

[Albedo]

Seating Depth is how far into the case the bottom of the bullet is (note: variance in seating depth varies the volume the case has for powder). QL the Seating Depth is the measurement from the base of the bullet to the rim of the mouth of the case. The Shank Seat. Depth is the measurement from the boat-tail/bearing surface junction to the rim of the mouth of the case (for boat-tail bullets, anyway).

Thanks for the explanation! Now it makes sense, I didn't think the Shank Seat Depth was from the rim to the bottom of the bullet before the boattail. I verified this in the CAD model just to make sure the value QL auto computed was correct, and indeed it is.

 

[Ned Ludd]

The other thing to note about QuickLoad is that it doesn't use cartridge base-to-ogive (CBTO) measurements for its seating depth or how much "shank in the neck" outputs. There are a number of reasons for this, the primary one being that CBTO measurements can vary widely between different reloaders depending on the diameter of the hole in their caliper inserts. Instead, QL uses cartridge overall length (COAL), which works because of the bullet OAL input. The important thing to note is that this means one actually needs to measure bullet OAL, not just use the average value provided by the manufacturer. This is because bullet OAL can vary widely, even within a single box of bullets, and the average value within a given Lot # of bullets may or may not be close to the manufacturer's value.

 

[Albedo]

The other thing to note about QuickLoad is that it doesn't use cartridge base-to-ogive (CBTO) measurements for its seating depth or how much "shank in the neck" outputs. There are a number of reasons for this, the primary one being that CBTO measurements can vary widely between different reloaders depending on the diameter of the hole in their caliper inserts. Instead, QL uses cartridge overall length (COAL), which works because of the bullet OAL input. The important thing to note is that this means one actually needs to measure bullet OAL, not just use the average value provided by the manufacturer. This is because bullet OAL can vary widely, even within a single box of bullets, and the average value within a given Lot # of bullets may or may not be close to the manufacturer's value.

Interesting to hear that the overall length can vary so much for the same manufacturer. I plan to give mine a simple +/- 0.01in tolerance for overall length, which that is actually a "looser" tolerance. So mins and max of 0.928-0.948in, which doesn't seem like it will effect much, especially since I am below the typical cartridge length to still use in a magazine.

 

[mikecr]

If it's a boat tail bullet I just pick available in cal and manually enter my shank seating depth.
That is, how much of bullet bearing occupies the neck.