oal question

[jerseymike]

I just purchased a hornady oal length tool, everything went fine but when I measured from the ogive I measured 2.116 to the lands, I set my seater for 2.106 to set it .010 from the lands, now when I measure from the bullet tip its way less than my reloading manual states which is 2.800. I think it came in around 2.74x? Something in that range, now is that normal? Or am I doing something wrong? I measured the oal by ogive 5 times the averaged it.

 

[Victor N TN]

Re: oal question

Measuring to the ogive will give you the length from the base to ogive. Measuring the OAL to the tip is something different. Base to ogive is pretty repeatable. OAL to tip is going to varry because of the way the jackets are made.

Measure 5 from base to ogive. Then take the comparator off your calipers. Now measure the COAL on those 5. Average it out. That's as close as it gets.

 

[mdmp5]

Re: oal question

To concur with Victor, the OAL is a different ballgame than the distance from the base to the ogive. Bullets, even match bullets have quite large variance between them, even from the same lot. If you took measurements of 20 bullets from a box of Sierra SMKs, you would see differences in bullet length, weight and ogive.

Instead of measuring distance to the lands and then using the average (mean), use the mode instead. I usually take at least 10 measurements to be sure. The mode is the value that appears the most amount of times. The mode is more reflective of a true measurement because it signifies repeatability. By doing it this way, you eliminate the possibility of having outliers skew your value, which will happen if using the mean.

This may seem to be mundane, but I believe in doing things meticulously as to minimize inevitable and unavoidable human error.

 

[jerseymike]

Re: oal question

sounds good, thanks guys for the help.