I wouldn't say that Wilson will not make 338 Fed barrels. But this is their current disclaimer on their barrel page.
Due to the unprecedented demand for our AR barrels line, we are having to make some hard choices on production to enable us to fill the most customer orders. In order to maximize our production and deliver the most barrels WITHOUT sacrificing any quality we must run higher quantities of fewer calibers and variations per production run. Until this massive panic buying subsides we will only be producing barrels in the following calibers and fewer variations within these calibers. We will fill backorders for other calibers / variations when we are able. Lead time is unknown at this time. .223/5.566.5 Creedmoor.300 Blackout300 HAM'R.308 Win.458 SOCOM