veczillaDisclaimer: I am not an audio professional, just a person with experience in shooting guns and concert plugs.
No, these are not suitable for shooting guns. These claim to be for music and as such would have a relatively light effect. For shooting you need robust protection and deadening of the noise.
veczillaIt depends on where you are shooting and what you are shooting. If you're shooting a 12 gauge, 30-06, 400 winmag, etc at an indoor range (not sure why you'd be shooting big caliber indoors but I'm sure it happens) then you would want something with much higher db reduction than these. Actual full coverage earmuffs with an ANSI S3.19 rating of 30+ dB reduction are what most recommend for shooting.
If you're outdoors with a .22 or sub sonic .308 then you can probably use these since those rounds are a lot more tame.