I recently bought a box of 100 Sierra 6mm 90gr TGK bullets to reload for my Tikka .243 Win. The BC on the website shows .490 above 2700 FPS. Yesterday I was at Academy and I noticed that they had some Sierra factory loaded 243 Win with the 90gr TGK so I bought a box because I haven’t had time to sit down at the reloading table and make up some test loads and figured what the heck I’ll just run these and if they shoot good out of my rifle I’ll just try to replicate it when I do have the time to reload. I got to looking on the box of loaded ammo and noticed it shows a BC of .390 so I sent an email to Sierra to find out if the website or the box has a misprint on the BC. This is the response I got from Philip Mahin, “ The bullet made for the ammunition has a slightly different shape than the bullet made for reloading. They have different BC numbers and the ones you quoted for both are correct for them in G1 numbers.” Is it a common thing for a manufacturer to label two bullets the same thing but actually be two different bullets factory loaded ammo vs. component bullets for reloading? Any which way I just thought I’d let anyone interested know that the bullets are different between the component bullets and the loaded ammunition

Ive never specifically heard of that, but do know factory loaded ammo can and often times is slightly different than when you buy components. One glaring difference is most component bought bullets don't have canelures, whiel most factory ammo is crimped and does have them.