Not even once.
It may appear to work at first, but in the end, you have to either fight or capitulate entirely.
Ask those who believed Neville Chamberlin....Gerrmany under Hitler still went to war, despite appeasement. Ask the jews in Israel.....Giving up territory just brought the rocket launchers closer. Appeasement fails every time.
It'll fail here too, if we let 'em take even some of our gains in 2nd Amendment issues. Gun control hasn't made anyone safer. Ever. If it did, then there wouldn't be the gun crime so prevalent in Chicago or Wash. D.C.
Banning of all guns hasn't worked in the UK, and certainly not in Australia. (wonder how many buried guns are there, waiting for the day?) and restrictions or bans won't make anyone safer here either.
All of these examples show that it doesn't work. "reasonable gun controls" won't be the end, just the beginning. The bar will move and we will then negotiate (or appease) to keep what we have left Then again a few years later..... Remember, the gun used by (supposedly) Adam Peter Lanza in Connecticut was legal under their "assault weapons ban" as well as under the old, national "Assault Weapons Ban" enacted in 1994. Banning others won't bring those kids back. Making another law won't make his actions any "illegaler" either. He (or someone) had 20 minutes before the police to do his deed. 10 round magazines would not have reduced his carnage at all. He would have had to reload more often, but that would not have materially reduced the level of violence nor his ability to kill those children in any way. He had nearly one minute per person...lots of time to do his killing. Possibly changing the ways we handle disturbed or mentally diseased individuals might, but that, like gun bans or restriction of speech is something approached with caution. It too can be a slippery slope.
Are you prepared to fight for your freedoms? Might have to, or you become a subject.
Which will it be?