What is the minimum length bearing surface in the neck?

[bikemutt]

I ask this because I'm loading a Nosler 6.5mm 123gr Competition bullet in a 6.5 Creedmoor case.

Nosler online reloading says they tested this bullet with a COAL of 2.775". Let's say my case is trimmed to spec at 1.920". If I seat to COAL, 0.855" of the bullet is outside the case (2.775-1.920).

The bullet is 1.200" long, if 0.855" is outside the case then 0.345" is inside the case. This bullet has a 0.200" boattail section (measured). So, 0.145" (0.345-0.200) of the bearing surface of the bullet is in contact with the neck.

From what I've read, we should expect the length of the bearing surface in contact with the neck to at least equal the bullet diameter, which it clearly doesn't in this case.

Would you lean towards more bearing surface within the neck, or to heck with it, Nosler knows best run with their load data?

 

[MtnCreek]

Assuming your measurements are correct, I would be concerned that I was creating runout if this is a typ pushfeed, feedramp loading rifle.

 

[Bfh_auto]

I use a default of at least 1 caliber width deep per caliber wide. I have never had good luck with less.

 

[old heeler]

I ask this because I'm loading a Nosler 6.5mm 123gr Competition bullet in a 6.5 Creedmoor case.

Nosler online reloading says they tested this bullet with a COAL of 2.775". Let's say my case is trimmed to spec at 1.920". If I seat to COAL, 0.855" of the bullet is outside the case (2.775-1.920).

The bullet is 1.200" long, if 0.855" is outside the case then 0.345" is inside the case. This bullet has a 0.200" boattail section (measured). So, 0.145" (0.345-0.200) of the bearing surface of the bullet is in contact with the neck.

From what I've read, we should expect the length of the bearing surface in contact with the neck to at least equal the bullet diameter, which it clearly doesn't in this case.

Would you lean towards more bearing surface within the neck, or to heck with it, Nosler knows best run with their load data?

I don't think when first mention bullet dia in the neck,they didn't have crystal ball to see all the VLD type bullets with longer BT. if that bullet you want to shoot, you may had to adjust COAL based on how bullet shoot. I would try them

 

[Poper]

I use a default of at least 1 caliber width deep per caliber wide. I have never had good luck with less.

I, too, stick to the neck engagement = to caliber diameter rule of thumb.
If you are loading them one at a time single shot style, as in competition loading, then you might be ok. As they are, I doubt they could withstand much in the form of field (rough) handling. You might get by with the short grip on the case with a light crimp, too.

 

[bikemutt]

I'm loading just 24 rounds for an OCW test. I took the conservative approach and seated to a COAL of 2.651", I figure if bullet jump is going to adversely affect one round it'll most likely affect all the rounds.

I may just be that this bullet is not the best choice for 6.5 Creedmoor. I'll see what it looks like in my 6.5 Grendel.

Meanwhile, I ordered a box of Hornady 123 gr ELD-M bullets to see if they may be more suited to the application.

 

[quest4perfection]

I use a default of at least 1 caliber width deep per caliber wide. I have never had good luck with less.

Found this so as well.