I am 5"1, 115 lbs, barely an A cup. I want to be a C cup, will 460cc HP Silicone under the muscle be too big?

There is no way to tell other than through a personal consult.  I find cup size is not very helpful to figuring out final desired breast size.  Look at my websites at the before and after pictures and you will see many women who's  afters are a much larger bra cup size then you would have guessed based on the pictures.  I find it is better to try on implants until they feel like the correct size and then the surgeon and patient will be on the same page for expected breast volume

Unfortunately, you have not told us your bra size just your
cup size. If you are 32 or 34 each 100
cc’s of implant corresponds to 1 cup size change. If you are 36 or 38 each 200 cc’s of implant
corresponds to 1 cup size change. From
this, you can compute the volume required to achieve your desired goal. 460 cc implants are large and if placed under
the muscle will extrude inferiorly and laterally requiring revision. I always recommend small round textured
silicone gel implants placed retro-pectoral since they look and feel more
natural, are more stable, less likely to ripple or have complications needing
revision. Implant profile is irrelevant
in the retro-pectoral position since the muscle compresses it. 22% of women who undergo breast augmentation
alone require revision within 2 years because they are dissatisfied with the result. Best Wishes,Gary Horndeski, M.D.

Hi Ashley,It is very hard to say without a physical evaluation or even a foto. That said 460cc is a  relatively big implants and should get you to your goal.  

Thank you for your question. It is not the size of the implants that matters most, but your chest wall, breast base measurement, tissue characteristics such as laxity, elasticity and tissue thickness. Anyone can shove a large implant under your breasts, but you have to discuss and consider the long term detrimental effect of a poorly thought out surgery on destroying your breasts and skin and end up a breast "cripple". Corrective surgery is always more expensive, involves more scars and less than ideal results. If your surgeon lets you be decision maker without proper counseling, please cut your losses now and see a board certified plastic surgeon for a proper evaluation. Right now your decision is reversible, after surgery it is not. BTW, do not expect to look "natural" with 460cc implants with your anatomy that you described. Good luck.

Only your doctor is in a position to tell you if this is an appropriate implant size based on your goals as expressed to him/ her as well as your dimensions and soft tissue characteristics.  I love 3D imaging to help me get a better idea of what "look" the patient is going for and to help her feel comfortable with the implant chosen.  For what it is worth, most patients of your height and weight would have an obviously implanted look and shape.  If you like the idea of a very rounded breast (likely a D+ cup) and have no problems with everyone you meet knowing they are implants you are probably on the right track.  If not, I would reconsider.  -York Yates MD, Utah.