l have this idea for a vampire hunter that uses a gun,with the ammo being little wooden spikes (pieces of wood shaped like bullets,with a sharp point). l am makeing this to ask if such a thing would be possable,like with a master blacksmith or artificer or something? obviously it would have to be a magic item,cause otherwise the bullets would burn/shatter upon fireing.

Totally not possible; wooden bullets used to be use as a form of blank/fake bullet in old musket and WW1 era rifles. The wood just burns up and disintegrates as it's fired.

You'd be much better off with silver, or maybe engraved with holy symbols.

Not entirely true.  Wooden bullets have been used for crowd control through pain compliance and the 1907 Schouboe pistol was designed to use a copper jacketed wooden projectile.  They must be fired with less powder and thus will have less velocity, but it is inaccurate to say that they always disintegrate like the wooden training ammunition you referenced.  

Ah, I wasn't aware of those, I was only familiar with the training rounds.

But those rounds you mentioned would be even less effective because they'd likely not be able to pierce flesh as needed for the desired purpose.

A bow or crossbow would be more reasonable. What is an arrow but a narrow wooden stake with pointy metal on the end?

Something like an underwater speargun might also be a possibility, but that would be much shorter range than an actual bow or crossbow.

How much suspension of disbelief do you have, and where are your co-players at?

A harpoon like one-shot-stake-shooter sounds cool enough to be fun.

Maybe if the wooden bullets were enchanted to be as hard as lead, but in the long run that is gonna be very costly. 

Also worth noting, vampires don't require wooden stakes to be killed in dnd

Quote from Zippa >>

Not entirely true.  Wooden bullets have been used for crowd control through pain compliance and the 1907 Schouboe pistol was designed to use a copper jacketed wooden projectile.  They must be fired with less powder and thus will have less velocity, but it is inaccurate to say that they always disintegrate like the wooden training ammunition you referenced.  

 So your argument against wooden bullets being ineffective as ammo is non-leathal ammo. While an interesting bit of trivia, it does not help the OP in the least.

I think the best solution would be a stake launching crossbow.

Quote from CharlesThePlant >>

Also worth noting, vampires don't require wooden stakes to be killed in dnd

 Only in the sense that they cant be killed at all, but at least a wooden stake through the heart paralyzes them indefinitely.

Well considering that this is D&D the bullets could be made from Bronzewood which in the forgotten realms is a very hard and heavy wood that is used by the elves to craft things.

Cool idea, but you are not the first to think of it.  Wooden bullets were used in this movie:

Sundown: The Vampire in Retreat (1989)

Hellboy uses a gun that has bullets containing wood, holy water, and silver.

https://hellboy.fandom.com/wiki/Good_Samaritan

But overall guys come on, this is a game with magic and spell and dragons and stuff. It's not too far fetched to have magic wooden bullets.

Quote from SagaTympana >>

A bow or crossbow would be more reasonable. What is an arrow but a narrow wooden stake with pointy metal on the end?

 ah,maybe it works like a crossbow,but looks like a gun?

My "argument" was to point toward historical examples of gunpowder propelled wooden projectiles, as the original post specifically referenced issues with wooden projectiles "disintegrating". 

Also, the Schouboe pistol was not designed as a less-lethal device; it was intended as an easily produced , low cost military sidearm.  It was not successful and did not win any contracts, but it did function.  My point in referencing it was to allude to the use of jacketing or means of containment to make wooden projectiles more viable.  So the pistol example and plenty of historical references to smooth bore devices like the classic Blunderbuss being loaded with debris, including shards of wood, would suggest that magic and master craftsmanship would not be required.  

Clearly a projectile made of wood would be less effective in virtually every scenario versus a more traditional bullet, but if the game in question has a take on vampires different from 5E source materials, there are certainly ways to deliver the "stake" via gunpowder or similar propellant.  

My argument will be towards magical ways to make it happen.  Like bullets made from ironwood, it is wood that is incredibly dense.  So much so that some heavier metal heavy armors can be used by substituting this as the material.  Granted this is from older editions but no reason why it could not be integrated into 5e in a logical manner.