Companion are made to fit a wide number of guns, but not all. Too small a bore, too large an overbore or short chambers might not work well. If your gun has 2 1/2” chamber you might have a fitting issue. You could measure your tube external chamber area at 2 1/2” and compare it with your chamber diameter of your gun. Or just gentle put them into your gun and see if they seat fully without any issues. I’d measure if you have the tools.
The .410 companion tubes tend to be easier to get into short chambers in my experience. I bought a set of old Briley skeet tubes, 20, 28 & .410 for $200.00 and cut them down to 20”. It reduced the weight and eliminated issues with chokes of the gun interference with seating. They were made for a very tight bore gun so they fit just about anything. If too loose I just add a bit of liquid nylon nail polish to the tubes. Fairly strong temporary thing to help fit. They are a lot like the old Browning Super tubes from the 60’s but with built in extractors. Weight is nicely between the hands.