Measuring to lands??

[cowtownup]

I'm trying to measure OAL to the lands with 2 different projectiles just for the sake of knowing more and recording more information regarding my handloads. I don't have the fancy equipment required so I have resized and trimmed a case to trim length and have slit the case neck as shown in the picture. I lubed the inside of the case neck and barely seat the bullet then chamber the round and measure. Here are the results:
1. 175 grain SMK ".............2.890"

2. 165 grain SpitZer BT.......2.816"

My question is why such a longer OAL to the lands with the 175 SMK. The projectile appears as if it would catch the lands sooner and seat deeper than the 165 SpitZer... I just want to make sure I'm getting good readings. Can anyone offer some explanation.

http://i185.photobucket.com/albums/x256/cowtownupp/IMG_20140410_162340_895_zps2fed2823.jpg (http://s185.photobucket.com/user/cowtownupp/media/IMG_20140410_162340_895_zps2fed2823.jpg.html)

[Luke45]

thats the same way i measure to the lands, seems to work fine.just make sure that the barrel is not gripping the bullet and pulling the bullet farther out of the case neck

[cowtownup]

I had not thought about the bullet pulling out as I remove the cartridge.. I went back and tried this several times and I get the same measurement each time which leads me to believe it's not pulling the bullet...

[Texas Solo]

My question is why such a longer OAL to the lands with the 175 SMK. The projectile appears as if it would catch the lands sooner and seat deeper than the 165 SpitZer... I just want to make sure I'm getting good readings. Can anyone offer some explanation.

http://i185.photobucket.com/albums/x256/cowtownupp/IMG_20140410_162340_895_zps2fed2823.jpg (http://s185.photobucket.com/user/cowtownupp/media/IMG_20140410_162340_895_zps2fed2823.jpg.html)

Simple. The lengths to the lands are determined by the bullet profile (shape), not the weight or length of the bullet. A bullet with a narrow, skinny profile will have to go further to reach the lands than a one with a blunt shape. Your looking for the point of where the "ogive" of the bullet touches the lands. All ogives are not created equal.
You might also try repeating the test without lube in the case.

[n4ue]

Yep, all about the ogive...........
Have fun.

ron

[cowtownup]

So can I conclude that the ogive on the 175 SMK is lower on the projectile which gives me a longer OÀL than the 165 Spitzer?

[Texas Solo]

So can I conclude that the ogive on the 175 SMK is lower on the projectile which gives me a longer OÀL than the 165 Spitzer?

Correct!

[slowshot]

The best way to work out seating and jump is to use a Comrariter (hope I spelled that right!) OAL will change with every style of bullet you use