Nathan, a few people have had the same issue. With use it should wear it in a little and become easier. You could hurry the process up by loading and unloading shells into it until it loosens. If you're comfortable doing so you could also use sand paper and lightly sand the inside but be sure to be careful not to remove too much. Lastly you could try several different brands of shells, some might fit better than others. Hope this helps.

Repeated use will make it easier to insert/remove shells but...If you want to get to that EASY point now then the light sanding idea will do the trick!!!
Thing there though, just do a little at a time then test fit, you go to much out of the gate and now you've got a loose fit problem!!
Good Luck!!

Hi Nathan and welcome. Since I don't know if you have the plastic shell holder or not, try these. If plastic, put a piece of masking tape around a spent shell and heat it with a blow dryer for a couple of minutes and then let it cool for a few minutes. Then retry inserting a live shell and check for tightness. You may have to experiment a little. Or you can use the shell holder I use without issue : amazon.com/TRINITY-SUPPLY-Compatible-Accessory-Tactical/dp/B08P54NWT3 -- Cheers and stay safe!