Yes, the only thing the Mass laws do is stop gun deaths "caused by negligence, suicide, or accident" and justifiable homicides - self defense or police shootings
Do background checks help prevent suicides or accidents?
On the other hand, waiting periods, permit to purchase, etc., may be more helpful in preventing suicides (or minimizing fatal suicide attempts).
What were the statistics and trends in Massachusetts before the laws were in force?
It's important to look at the intent and effect of proposed (and on-the-books) legislation, and at the context of statistics.
There is a good discussion of various factors (duration of suicide crises, availability of means, opportunity to abort the attempt or be rescued, and the lethality of the mechanism).
"Nine out of ten people who attempt suicide and survive will not go on to die by suicide at a later date."
"A number of studies have indicated that when lethal means are made less available or less deadly, suicide rates by that method decline, and frequently suicide rates overall decline. This has been demonstrated in a number of areas: bridge barriers, detoxification of domestic gas, pesticides, medication packaging, and others."
https://www.hsph.harvard.edu/means-matter/means-matter/saves...