i have a woody magnum that is about a year old and the bands are still in good shape but im having a problem getting it to stick in fish lately. i have shot plenty of thick skinned fish (cobia, spade fish etc) but lately i have had a lot of fish come off. i am shooting a break away  and i just shot a large trigger fish and grouper that the point didnt stick to only one flopper is making it in the fish. was considering going up to a stronger band. any advice would be helpful.

Change out the bands. 

Not sure how often you shoot the gun but if the bands are a year old they probably need changing.  They may look fine (i.e. not dry rotted) but to me i find they are noticeably loosing their snap about 6-8 dive trips (thats about 30-50 shots the way I dive).  Even a year old gun could have sat on someones shelf for a few years prior to purchase and the bands are that much further weakened.

I time my band changes so that I start with fresh rubber at the beginning of each season and usually change em out once again mid season.  I keep a few of the old bands on the boat or in the bag as spares (in case I break or damage a fresh one).    

In between trips I keep them in the freezer…it really does seem to make a difference.   If you dont dive that much and keep the bands stored out of the sun and heat you may get more mileage than me.  Fresh bands are cheap enough insurance that I try to change them 2x a year, but once a year is the bare minimum.