Yup.....I think the flat face bolt.......or one of the rubber tip modded ones with an anti roll back feature will help more than anything. BUT.......since you don't have that, you need to take other steps.
Lower that hopper tension for sure. Rollback with brittle paint is just made worse with a heavy stack tension.
Next the whole large bore/small bore thing. Punkworks isn't doing their testing with paint so cold it's ready to shatter when you look at it. When nice warm flexible paint is fired, it will bend and stretch inside the barrel without a problem. With cold brittle paint, it won't. You want the paint to fly down the barrel with as little resistance as possible. Over bore.
Detents. Your detents may be in good shape and retracting BUT....are they retracting 100% of the way? I do the finger nail test. I press the detent in until my finger nail is flush with the breech of the gun. If you can't get your finger nail flush, then there is a problem and your detents may be cutting paint. A piece of shell, a buckled spring, a piece of dirt.....could all prevent detents from retracting 100%. Double check them.
Make sure your board settings are correct. Sometimes things get changed by mistake when people mess with your gun. Things like dwell, BIP, EYE delay......if they get messed up you can have problems.
Now if you have roll back issues, you really need to run your bolt pressure as low as possible. Might want to raise that dwell higher than you normally would to do so. Bump your BIP setting up a tad more for safety. Take out any efficiency mods you may have in. You want low pressure.......which will reduce your bolt speed(energy), and also slow down the shock on the paintball when fired. Make sure the FT isn't in too far.....it may be causing the gun to under cycle. I'm no luxe expert so I don't know where it should be set when running a higher dwell. Ask around.
Next time you play, pay attention to the other luxe setups. See what they're running as far as settings, bolt type/mods, hopper. See what you can learn.
If things get really bad you can always dump all your paint in the box and let it sit in open air for a while. It will soften up a bit and add some flex to the shell. That may help. Most gun makers are starting to catch up with the roll back issue since paint is so small these days. Some have not.....the flat face bolt is a must buy for the luxe in my book. Or any other bolt with anti roll back fixes. Paint is just so small these days that it really is a problem for people who play in cold weather.
ETEK 3LT, with 14" critical .680 barrel and cure 3 + bolt F/S