... maybe you've relied on others to tell you the rules without checking for yourself. Scott H does tend to interpret them much differently than intended.)
For others reading this thread that do shoot don't be afraid to question another shooter if you feel they aren't following the rules. If you don't want direct confrontation note the transgression and report it the MD. If they aren't willing to enforce the rules as stated I'd be suspect of thier safety practices as well.
"...Scott H does tend to interpret them much differently than intended...." Assuming you mean Scott Hull (me), I'll respond - not really knowing what the intentions were/are, I interpret the rules as written, not as intended.
As far as the adjustable hamster question - my interpretation for Hunter Division is that an attached hamster must not extend more than 6" below the bore-line, and it cannot be adjusted during the match. And I would also interpret that to preclude installing/removing during the match as a restriction, as that results in an adjustment to the rifle.
I have never used a "hamster" in Hunter Division, and prefer to use a for-end that is as shallow as possible. When I need a little extra elevation angle, I'll sometimes use a slightly resilient pad that is 2" thick. It is not attached to the gun.
Early Hunter Division allowed attached bipods as the only attachment that could extend below 6". After the attached bipods were outlawed for shooting, I had questioned whether we could still use the bibod as a stand when not shooting. It was debated, and I still see a few people with attached bipods as stands. Since the bipod would almost certainly extend more the 6" below the gun when folded-down, it would have to be folded-up when shooting. And since "folding-up" could be considered an adjustment, then technically, it is not allowed by the rules. So I no longer have attached bipods as a stand on my Hunter Division guns, even if I never intended to "use" them down while shooting. Doing so would be a technical violation. If I see someone doing it, I might not even mention it, especially if I'm not the match director.
I have shot at a number of matches with Scott S, and as a match director, I do remember wondering if his hamster was over 6". It looked close. I see lots of things that look close. Unless things appear to be obvious violations, I'm not inclined to get out a tape measure. If it had been obviously over 6", I would have brought up the subject to him. Whether he removed it for his sitting shots, I didn't know. In the case we are discussing about Scott S, the question is not whether the configuration was legal, because it was legal either way. The question is about when it was installed. It's OK do do it before the match starts, but once it starts, it's too late to adjust/remove it.
WFTF allows adjusting, but explicitly forbids installing/removing items. Open Division allows installing/removing/adjusting items during the match. Hunter Division explicitly forbids adjusting anything for the duration of the match - which implies no installing/removing.
Having supposed/imaginary violations pointed out during a match (especially while shooting) is annoying. #1 - make sure you know the shooter's Division. #2 - make sure you actually know the rule as it applies to that Division. #3 - if #1 and #2 are met, then we have a duty to advise/confront the shooter that is in violation. If I see someone tightening or otherwise messing with the gun between lanes, I don't usually question what they are doing.
Safety rule violation, advantage rule violation, technical rule violation - each approached differently. Removing a hamster during a match is not a safety violation or an advantage violation. I consider it a technical violation - and I see technical violations quite often.