I just picked up a growler of porter from the Berkshire Brewing Company and I noticed that the metal screw-top was a little different from the plastic screwtop on the only other growler I have (from a HBS). The HBS growler has a little plastic bit on the inside of the cap, I assume to make the screwtop safe to use for bottle conditioning. Do you all think the metal screwtop will work, or should I play it safe and not use it?