I recently purchased the Sinclair OAL gauge and bullet comparator which finally arrived on my door step today. Now I need help interpreting the measurements.
Just for reference the gun is a CZ 550 American in 6.5x55 SE and the first bullet tested was the Sierra 6.5mm 160g semi-point.
Following the instructions I measured the bullet base to tip (step 1) and got 1.260".
My measurement from the cartridge head to the base of the bullet (steps 2 through 9) was 1.750".
The final step says to measure the length of the bullet and add this to the measurement used in step 9 (1.750"). But... didn't I get that measurement already in step 1? Or is this a different measurement?
Anyway, by adding the two measurements I get 3.010" cartridge head to bullet tip.
Now, I know that it's best to measure a bullet on it's ogive which is what the bullet comparator is for. If I measure the the bullet in the comparator (just the bullet) I get a measurement of 1.824". This is from the flat side of the comparator to the bullet base.
The measurement (if this matters) of the comparator from the side marked "26" to it's opposite side marked "25" measured at 0.98".
So what does all this tell me? How do I put these numbers together properly to get the OAL for which the bullet touches the lands? What else do I need to do to get my optimal OAL? I know that generally a bullet should sit 0.015" to .02" from the lands so that I'll need to subtract that from my final measurement, but I'm not sure what my "final measurement is."
Sorry if this is a noob question, I feel stupid even asking it but I'd rather get this right and know how to do it properly.
Just for reference the gun is a CZ 550 American in 6.5x55 SE and the first bullet tested was the Sierra 6.5mm 160g semi-point.
Following the instructions I measured the bullet base to tip (step 1) and got 1.260".
My measurement from the cartridge head to the base of the bullet (steps 2 through 9) was 1.750".
The final step says to measure the length of the bullet and add this to the measurement used in step 9 (1.750"). But... didn't I get that measurement already in step 1? Or is this a different measurement?
Anyway, by adding the two measurements I get 3.010" cartridge head to bullet tip.
Now, I know that it's best to measure a bullet on it's ogive which is what the bullet comparator is for. If I measure the the bullet in the comparator (just the bullet) I get a measurement of 1.824". This is from the flat side of the comparator to the bullet base.
The measurement (if this matters) of the comparator from the side marked "26" to it's opposite side marked "25" measured at 0.98".
So what does all this tell me? How do I put these numbers together properly to get the OAL for which the bullet touches the lands? What else do I need to do to get my optimal OAL? I know that generally a bullet should sit 0.015" to .02" from the lands so that I'll need to subtract that from my final measurement, but I'm not sure what my "final measurement is."
Sorry if this is a noob question, I feel stupid even asking it but I'd rather get this right and know how to do it properly.