I currently shoot 55 grain and was wondering if you guys can post some advantages or disadvantages with 55gr vs 62gr.  Also if you change between the two does it affect the zero when taget shooting.  The bullet drop should be the same because gravity is gravity.  Any input would be appreciated.  TIA

Bullet drop changes not because of weight but velocity. Velocity changes because of weight, ballistic coefficient, powder charge, etc. IOW, zero does change.

Check out this trajectory calculator:
internet.cybermesa.com/~jbm/ballistics/traj/traj.html

ronin
Man that trajectory calculator is intense.  I like it.  
So would you say the 55gr vs 62gr. would depend on the application?  Other than that no real difference?  

Thanks Kevin
I looked around there a little before I posted but I'll look again.

Quoted: Man that trajectory calculator is intense.  I like it.

It is pretty cool, isn't it? I found it a while back and share it's URL w/ all interested parties. It's kind of tough to know all of the required info to fill in all of the blanks. But it does allow you to do "all else being equal" type what-ifs.

So would you say the 55gr vs 62gr. would depend on the application?  Other than that no real difference?

Well, I wouldn't say no real difference but it's definitely an application question. For example, what's the twist rate of your rifle's barrel? Heavier bullets require faster twist rates. To what kind of distances are you shooting? Longer distances are better served by heavier bullets with better ballistic coefficients. At what kind of targets are you shooting? 62gr M855 will penetrate harder targets.
Rezeroing won't be a necessity for hitting MST's at distances less than 200 meters (maybe even 300) if you change ammo loads. But for match grade accuracy at 600 meters, you'd better start making elevation adjustments.
Also not all 62gr bullets are M855's so their "applications" might be different.

Thanks Ronin
What you posted makes a lot of sense. You apparently know you stuff.

Quoted: Thanks Ronin What you posted makes a lot of sense. You apparently know you stuff.

Aw shucks. Just sharing what little I know. Just like everyone else here. Besides, it beats working.

ALL OTHER THINGS EQUAL THE 55 GRN SHOULD PERFORM BEST IN A 1:12 TWIST BARREL AND 62 GRN BEST IN A 1:9 BARREL.  (ACCURACY)

(Please pardon the caps.)