Gold Tip makes weight tubes that thread into the back of the insert.I've installed them on arrows that have the inserts already installed. Just remove the nock and use a long rod with the end filed down to fit the allen head. They come in multiples of 20 grains each. I'm not familiar with diameter of the epics, so I'm not sure if they would work for you or not. I think it's a good idea to use medium threadlocker if you use them, so they don't come rattling loose. I put them in my arrows and increased my FOC and overall weight (for elk hunting).