the issue is trump has no core beliefs, he's just a typical fast-taking bullshitting NY real estate guy who's only interest is self interest and will say pretty much anything at any time if he thinks it will gain him some advantage. he may very well try to move on this if he thinks it will get his poll numbers up and turn public opinion against the mueller probe. as tea said, it won't be easy since it goes against his base and the NRA but he may make the calculation that he can pull it off and come out ahead.
remember, this is the guy who has managed to convince conservatives that putin is an ok guy and russia is nothing to be worried about (despite every intelligence agency on earth concluding that they influenced our election), and convinced budget-hawk republicans that skyrocketing deficits are ok. i never imagined anyone would be able to do those things, but he has, so you never know.
personally, i don't think he will make a notable difference on the issue. he will preside over a very (very) modest change in gun laws and claim it to be an amazing victory, but it will be fairly meaningless in the scheme of things and have negligible positive impact.