Myth Busted! But a new villain lurketh...
Further to shotzee's post, here is the definitive Tavor magazine assessment... The following are the approximate height increase (+) of the bolt hold open when a magazine is inserted, from the default position. The results were...
quite interesting! Read on for details...
Note: On my Tavor, the BHO is by default about 1mm below the top of the BHO enclosure. My Tavor is one of the very first batch and is running the modified IWI civilian bolt.
HK416 Maritime, 30-round (control) .. 0mm (1-rnd) / 0mm (2-rnd)
PMAG 5-round (modified 20-rnd) ..... 1mm (1-rnd) / 0mm (2-rnd)
PMAG 20-round ............................ 1mm (1-rnd) / 1mm (2-rnd)
PMAG 20-round (modified 30-rnd) ... 2mm (2-rnd) / 0mm (1-rnd)
PMAG 30-round ............................ 2mm (1-rnd) / 1mm (2-rnd)
PMAG 30-round MagLevel ............... 1mm (1-rnd) / 0mm (2-rnd)
(These include the black, standard green and modified green followers)
Lancer L5 30-round ....................... 0mm (1-rnd) / 0mm (1-rnd)
LAR-15 10-round (Magpul follower) . 3mm (1-rnd) / 0mm (2-rnd)
LAR-15 10-round (std w/ranger) ..... 3mm (1-rnd) / 0mm (2-rnd)
Surefire 60-round ......................... 3.5mm (1-rnd) / 0mm (2-rnd)
Before we go any further analysis, I want to unequivocally state that
regardless of magazine/rounds remaining, at no time did the BHO ever rise enough to come into contact with the bolt. Let me also preface this observation by stating that I have
zero wear on the bottom of my bolt and none on my bolt hold open.
On to the myths!
...
Myth 1: PMAGs can damage the BHO/bolt on your Tavor
False. Even if the default position of your BHO is raised 1-2mm above the level of the enclosure, there is still between 0.5-1mm of clearance. With a PMAG. This includes all Magpul factory PMAGs as well as 2 types of customized PMAGs (all third gen).
Myth 2: Magpul followers on LAR-15's can damage the BHO/bolt on your Tavor
False. I tested two different LAR-15 magazines (different generations); one with the standard factory grey follower and another with a Magpul green follower. They
both increased the BHO by 3mm (!) when down to the last round.
Myth 3: Some magazines can damage the BHO/bolt on your Tavor
Plausible. If your BHO is raised 1-2mm about the level of the enclosure (slightly out-of-spec), using a LAR-15 (regardless of follower) 10-round magazine or a Surefire 60-round magazine could potentially lead to wear on your BHO and bolt.
...
That being said, I don't have any reason to disbelieve TV. He clearly had some issues and the premature wear on his bolt could certainly have been caused by the BHO. But based on my own (albeit limited and certainly unscientific) testing, I'm wondering if the culprit isn't the LAR-15 combined with something else out-of-spec?
So it looks like PMAGs are
safe and good-to-go. But if you want to err on the side of caution, either the Lancer L5 or Lancer AWF polymer magazines will work flawlessly. As for the LAR-15... well, I've used LAR-15's quite a bit in my Tavor - so it was initially a bit disconcerting (to say the least). I honestly never really thought to test them and did it merely as an afterthought.
On the LAR-15, on my Tavor I had at least 1mm of clearance between the top of the BHO and the bolt lugs. Even with the Surefire there was still 0.25-0.5mm of clearance. From where I sit the only time this could potentially be a problem is if the default position of your BHO rests slightly above the enclosure.
I'd be very interested to hear of any other Tavor owner's observations.