FX Fx m3 removing bottle difficulty

So I have a mk2 and I can remove the bottle on my gun with 1 hand holding the gun and 1 hand removing the bottle. But I just got a m3 impact with 380cc bottle from a agn member and when I remove the bottle it's always very hard. I can't remove the bottle with 1 hand like I did with the mk2. I have to have someone hold the gun and I have to grip the bottle with both hands and twist very hard inch by inch until it bleed the air then I can easily remove it. I know it's under pressure but why is it so hard to remove the bottle on the m3 vs on the mk2. Threads look find and no cross threads. Is there any way to make removing bottle easily? Maybe lube the threads with something? Also is it OK to be removing the bottles on and off? Cause thinking of getting extra bottle to swap out when in the field. But see video of earnest saying bottle should not be remove back and forth due to wear and can damage it. So I guess the impact isn't bottle swappable?