Depends on what you are after from a 'sniper'
There is no advantage to a sniper style gun over a standard style gun. They are more of a disadvantage in that they are bigger and bulkier
Everyone going into a game has the same velocity maximum and are therefore on a level playing field. The difference being matching paint and barrel (and adjusting to preference of a match, overbore or under bore depending on opinion and testing)
With firststrikes over paintballs you can get an advantage, but have to drop velocity to switch paint unless you are only using first strike. The a5 won't feed first strike
FS perform differently due to the fin design, giving extra range but less energy at range, and a straighter / more consistent flight path
Add a cross bow scope and a lot of time / money into target practice and you get predictable results
A long barrel beyond the optimum point just takes more air to push further up the barrel and therefore is less efficient
For the sniper look the a5 has a good start in that body kits are plentiful, add a long barrel, shroud stock and bipod and you're there.but it won't be cheap
We rebuilt one converting an ops gear body kit when my mate sold his a5
Originaly the a5 in a Barret body kit was just giant and cumbersome which meant it was never used
I had a pcs us5 which is pretty much an a5 clone, with a stupidly long barrel this was very accurate
For intimidation value we tweaked the body kit and installed on the us5
We found this perfect in one particular situation - sitting on top of a hill suppressing the tower which dominated defence of a village
Then when the tower was clear dump the rifle and move in with a normal gun