The only time a Silencer will impede your accuracy is if you use too long of one with a stock length barrel, then the bb will hop before it reaches the end of the Silencer, and will usually hit either the foam as Maciek mentioned, or the end of the silencer and send the bb's all over the place, or break em.
Use a silencer for a hidden inner barrel or use a shorter one just for looks.
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W1-5
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