Yes, but every plane is ultra vulnerable when landing/taking off or stationary in the ground, Allied was outnumbering Germans by a great amount on late stages and they tried to attack Me 262 in this time, because they could't defeat then in the sky. The unique guy born in Americas that got "knight's Cross of the Iron Cross", defeated 11 aircraft in the ground with his Bf 110 in a single mission(
https://military.wikia.org/wiki/Egon_Albrecht-Lemke) There are records of Me 262 destroying formations of bombers in "combat box" formation and their P-51 scouts unable to do anything. About MG 42 fire rate, it can be modded to 1800 rpm, but if an plane has 4 MG 42, each one with 300 rounds, in 10 seconds, the plane will ran out of ammo with an single 10 second burst. IF none of the MG 42 "jam"...
The thing I'd heard about the 262 was supposedly some vulnerability peculiar to that particular aircraft, though I don't recall anything about the details, so it may or may not have been all that special.
I can see that conceptually an MG42 could theoretically be modified to obtain an increased firing rate as were several other recoil-operated aircraft guns were by lightening the barrels, given that they didn't need the same heat-absorbing mass thanks to increased airflow e.g. the Brownings in both .303 and .50 calibre as used by the RAF (ISTR they used a compressed air recocking system which could presumably clear at least some stoppages) though I hadn't heard of the MG42 being used in such a manner and would be somewhat surprised as my understanding is that the Luftwaffe preferred much larger calibres (I heard one related anecdote where an ex Luftwaffe pilot described the amusement they shared at the RAF fitting Spitfires with rifle-calibre weapons... which quickly evaporated once faced with the reality of being on the wrong end of eight modified Brownings all firing at once). I should look it up now that my interest has been piqued, though I am a little sceptical.
Never got to fire any of the things in question during my brief stint in the army, sadly. Closest I got was having to lug a Bren about for someone else to fire (or not, as turned out to be the case) though maybe that's as well as I wasn't a great shot.
