Jordi Rubio are the first to release a metal replacement barrel for the recent Trumpeter kit of the 12.8cm Selbstfahrlafette L/61 "Sturer Emil" (kit #00350) which consists of just two parts in turned/machined aluminium.
There is the full length barrel and separate muzzle brake which are cleanly turned/machined without any surface blemishes apart from some minor cleanup needed on the inside of the muzzle brake openings.
Unfortunately there is no detail at all on the barrel with the kit barrel having more detail on the rear collar and muzzle brake collar and no detail on the inside of the one piece muzzle brake.
The muzzle brake is not actually hollow, there is a round hole drilled lengthwise and the two gas holes in the muzzle brake are hollowed out through the middle but the sections surrounding the hollowed out gas holes are solid metal.
The metal barrel is also the same size as the Trumpeter barrel which appears to be slightly undersized compared to available data.
Fitting this barrel is straightforward as it simply replaces the kit barrel and slips straight into the kit mantlet the same as the kit barrel.
Unless you absolutely need a metal barrel, this set offers nothing over the kit barrel other than there is no join seam to remove and actually has less detail than the kit barrel it is supposed to replace.
Not recommended unless you must have a metal barrel.