New to reloading with question about importance of BC. If I reload two rounds for the same rifle and cal. (300 WSM) with the same powder, type and amount, primer, case, bullets of the same weight and design but slightly different BC will it make a significant difference? I know there are a lot of variables in reloading, don't know if I'm being too picky but can't find anywhere else. Thanks.
... slightly different BC will it make a significant difference?
BC is how easily the bullet flies thru the air, if it slips thru the air more easily it will be flying faster at any given distance. The importance of this is the Time Of Flight will be quicker. Gravity has less time to act on it and crosswinds have less time to push it sideways. Maybe of less importance with a 300WSM but also a factor is a higher impact velocity will arrive with more energy.
Most people use a G1 BC although there is also a more refined G7. Most bullet manufacturers state a single G1 BC. This is an average guess because BC varies with velocity. So the same 30 cal 165gr bullet coming out of a 308 vs. a 300 Ultra "should" have 2 different BC's, but most manufacturers will state only one based on an average velocity. Sierra does break it down into velocity categories.
If you are shooting big game with your 300WSM at less than 300yds slight BC differences wouldn't have a "significant" performance difference, but significant is relative.
Best way to answer your question is to have "you" decide based on "your" intended use of the bullet. Plug your bullets and data into a ballistic calculator and get an answer with real numbers. Compare, drop, drift, and energy. Handloads.Com Ballistic Calculator
Stand up and be counted, join an outdoor sports organization
Life NRA,Life PTA,Annual SCI
If you calculate that is fine.Sight in for that.If you change powder or bullet weight sight in for that.One thing for sure is you need a chronograph.If you think published speeds are yours,well they are not.I wanted a chronograph really bad actually my wife got upset with the one I wanted.I got a CED M2.If you do a little research they are better than some cheaper models.Wasn't the one I wanted but I have one.I wanted this Oehler Research, Inc.-- Model 35P