Trouble with determining base to OGIVE measurement in 28 nosler. Using Hornady OAL Gauge. PLEASE HELP.

[bnewt3]

Quick related question. Why do monos like more jump?

My quick thought is solid copper is more resistant to forming than cup & core so the pressure required to get the bullet to form into the rifling is higher than a jacketed bullet. If seated too close to the lands there would be a larger(or at least more vertical) pressure spike when it hits the lands.

If thats the case, I would also think monos run slower than cup & core(assuming equalish shape and same weight & charge) because more energy is consumed forcing the bullet into the bore.

Am I way off?

 

[Harvey_NW]

Quick related question. Why do monos like more jump?

My quick thought is solid copper is more resistant to forming than cup & core so the pressure required to get the bullet to form into the rifling is higher than a jacketed bullet. If seated too close to the lands there would be a larger pressure spike when it hits the lands.

If thats the case, I would also think monos run slower than cup & core(assuming equalish shape and same weight & charge) because more energy is consumed forcing the bullet into the bore.

Am I way off?

I think you're spot on. I don't shoot mono's or believe in seating depth tuning, but it is commonly stated from the guys that do that they shoot better with some jump. Since they all seem to agree and the results align amongst random rifles, I'd guess that the pressure theory of being close to the lands has an affect. It is known and documented that over pressure loads can be erratic.

 

[Caseknife]

Quick related question. Why do monos like more jump?

My quick thought is solid copper is more resistant to forming than cup & core so the pressure required to get the bullet to form into the rifling is higher than a jacketed bullet. If seated too close to the lands there would be a larger pressure spike when it hits the lands.

If thats the case, I would also think monos run slower than cup & core(assuming equalish shape and same weight & charge) because more energy is consumed forcing the bullet into the bore.

Am I way off?

First thought is correct, harder material, more resistant to engagement.

Second thought, it depends on the design of the bullet.

 

[JFK]

Monos don’t shoot slower. Some, like Hammers, will shoot a decent amount faster than lead of equal weight. Jumping monos is due to engraving force. Harder metal. They shoot accurately with a lot of jump so it’s not really a downside.

 

[bnewt3]

Monos don’t shoot slower. Some, like Hammers, will shoot a decent amount faster than lead of equal weight. Jumping monos is due to engraving force. Harder metal. They shoot accurately with a lot of jump so it’s not really a downside.

Do you have an explanation for how they shoot the same or faster?
Less friction in the barrel after engraving perhaps?
Im a curious type.

 

[JFK]

Do you have an explanation for how they shoot the same or faster?
Less friction in the barrel after engraving perhaps?
Im a curious type.

Nope. Have just loaded lead and copper and observed the difference. Mostly get around the same velocity for a given weight with Barnes. Hammers and McGuires are copper and have beaten lead by a little…say 50-100fps. Most of this data is with a 270win, so not conclusive but that’s what I’ve seen. It might be that modern copper bullets have drive bands in the bearing surface which reduces actual contact with the rifling? Again, nothing scientific. Just what I’ve observed.