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AR15.COM
9/23/2015 10:47:59 AM EDT
I'm working on load development for my rifle, and using both the 105 A-Max and the 107 SMK. I have my dies set to seat at 0.020" off the lands with the SMK's, but the A-Max when mic'd reflects only a 0.010" jump. Verified by loading a couple more 107's, but the 105's still show a shorter jump. Any ideas? I'm thinking it is just the poly tip on the A-Max versus the OTM of the SMK, but I'm relatively unfamiliar with "match/precision" loading.

9/23/2015 11:20:21 AM EDT
[#1]
I had a problem once with bullets bottoming out in the seating stem.  It was.223 and loading vld's for me. Have no experiance with the heavy .243.
9/23/2015 11:50:34 AM EDT
[#2]
I hope you're using the ogive measurement instead of oal ( which can be up to +/- .010).  Different bullets, different profiles.
9/23/2015 12:21:01 PM EDT
[#3]
Step 1: Make sure you are measuring from the case head to the ogive, not the projectile tip. You'll need a bullet comparator for that which clips onto your caliper/micrometer.

Step 2: SMKs have a tangent ogive, Amax have a secant ogive. If you switch back and forth without resetting your seating die you will not get consistent jump.

Step 2 is true for ALL reloading, you should not switch bullets around without resetting your seating die. On most dies/bullets the seater stem doesn't precisely contact the bullet's ogive, it just contacts some random point on the bullet.
9/23/2015 12:38:34 PM EDT
[#4]
Duly noted, thanks for the replies. As i have stated, I'm relatively new to load development from a precision standpoint, and this is the first run at using multiple bullet manufacturers. I was not aware of the variance.

My old Mauser and my AR have only ever had one bullet breed through them from a reloading standpoint.

Comparator on the way tomorrow.