I have a manners t4 that took to my smith for flush cup install on the left side of the stock. I just assumed he was using quality flush cups like grov tec. Well I get it back and go to put my tab sling on it and the sling pulls out of the cups. The only loop attachments that work are the ones it came with and they are only 1". I call him and figure out they are uncle mikes pieces of shit. So I'm wondering if the um cups can be removed and replaced with grov tecs? I know they are epoxied in there.