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Old May 10, 2019, 02:57 PM   #2
Unclenick
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Join Date: March 4, 2005
Location: Ohio
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In 300 BO, Hornady shows 2.090" COL for the FMJ and 2.210" for the IB. Hodgdon adds another 0.025" probably because it fits their gun well. The IB has no crimp cannelure suggesting seating depth, but the main difference is the FMJ has a shorter tangent ogive radius so its stubbier ogive won't let you put the tip as deeply into the bore as the IB's longer secant ogive does before the bullet makes contact with the throat.

So, no, bullet weight isn't everything. The geometry has to be considered, too. There's an article by Allan Jones titled Practical Effects of Bullets on Pressure that shows same-weight bullets can cause pressure to vary 30% if you don't load to match them correctly.

50 years ago it was mostly true that weight alone told you what you wanted to know, but there were no secant ogive or VLD shapes or copper solids and the like back then. Bullet variety has expanded immensely since that time.
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