OAL of 3 Manf. bullets the same

[billmo]

Just an observation. In .223 AR 15 A4 Varminter I have checked three different manuf. bullets for OAL measuring with the stoney point tool measuring to the ogive and this is what I found. Is this a coincidence or are these three manuf. placing the ogive at the same location on these bullets on purpose? This is the first time I have seen this happen with three different bullets
and it caught my attention.

Sierra 69 gr. HPBT Match 1.919
Hornady 75 gr. A-Max 1.919
Berger 75 gr. VLD 1.919

Any thoughts?

 

[mc223]

I would say coincidince. Or conspiracy.
i set all my bullets regardless of manufacturer to the same ogive length.

 

[billmo]

So, if you do that then you will not be the same distance from your lands with bullets that have the ogive set forward or backward from each other? Please explain. Thanks, Bill

 

[mc223]

By coincidence, setting a 69 SMK to jump .030 and setting a 75 A-Max to jump .030 is the same. The cartridge overall length of the 75 will be considerably longer and the 69 might still make mag length. Manufacturers set to SAAMI chamber specs and all will jump to the lands, regardless of bullet type.
It just has to do with the differences between a tangent ogive bullet, 69 SMK )and a secant ogive,the pointier ones). I am only refering to loads that I use in my match rifle, but do practic some similar techniques with other loading and calibers. Once you have found a good load with bullets seated to book or mag length, you can start easing them closer to the land and see if the groups tighten or loosen. Some tangent ogive bullets tend to favor a jump where the secant ogive or VLD types tend to like to be into the lands.
Once you know where the land are you can easily adjust for accuracy and performance.

 

[billmo]

Yea mc223, I understand what you are saying. I don't even worry about measuring from the tip of my bullets unless I am trying to get the bullet into a magazine. Thanks, Bill