Received phone call last night about inconsistent reading to lands. Thought I'd pass this on. As we where discussing the problem he had noticed some marking on the shoulder at the neck area. We discussed several potential problems and decided it was carbon build up in the chamber. After a real cleaning of the chamber the measurements became consistent. Now he gets to go back and make a new once fired modified case for measureing and can start over on his load development. I must admit that if he had not told me about he marks I am not sure I would have come to this conclusion as quickly.
inconsistent reading to lands
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DrMike
Ballistician
- Nov 8, 2006
- 38,175
- 8,245
The little clues are often the determinate that solves the mystery.
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Mountain Goat
Handloader
- Dec 14, 2010
- 386
- 12
I always take several measurements with the Stoney Point/Hornady OAL tool. My method involves taking 3 measurements, rotate the tool 90 degrees-take 3 more measurements, continue this until you have 12 total measurements, each 90 degrees from the next. Think of it as looking at crosshairs. The nut on the OAL tool points at the end of the crosshairs. Or, like on a clock, 12, 3, 6, and 9 o'clock positions. I will do this with three bullets to help factor any inconsistencies in bullet ogive. I am not going to measure and separate the bullets for hunting rifles. Once I am done with all the measurements, I calculate mean, median and mode for each group of 3, and the entire group of measurements.
I use this method mainly for two reasons:
1. I shoot my rifles fouled, not bare metal clean. This method allows for a mesurement that is consitent with how the rifle will be shot. I call it "accuracy fouled."
2. The rotating of the OAL tool will help eliminate any inconsistent readings from concentricity issues with the tool, bullet, or if one land has more carbon than another.
I use this method mainly for two reasons:
1. I shoot my rifles fouled, not bare metal clean. This method allows for a mesurement that is consitent with how the rifle will be shot. I call it "accuracy fouled."
2. The rotating of the OAL tool will help eliminate any inconsistent readings from concentricity issues with the tool, bullet, or if one land has more carbon than another.
