This release from RB Mode is a replacement 152mm ML-20S barrel for the Soviet ISU-152 SPG of WWII and Postwar and and is designed primarily for the older DML 39-45/Korean War series ISU-152 kits.
It should be noted the ISU-152 (in Russian ИСУ-152) is incorrectly referred to as the JSU-152 in the West. This is due to ‘Iosef Stalin’ being pronounced Joseph Stalin in English, but there is no J in the Cyrillic alphabet, hence the correct translation should be ISU-152.
As with all RB Model sets there are no instructions or fancy packaging, just the parts in a zip lock plastic bag and a simple B&W label which isn't a problem with this set as assembly is very straightforward.
The set consists of the aluminium barrel a machined brass muzzle brake and is basically identical to the armorscale 152mm ML-20S Barrel for Soviet ISU-152, set #B35085 apart for the longer neck pin and no etched or resin parts.
The metal barrel has the correct taper and step segments and also features fine rifling inside the hollowed out muzzle with the machined brass muzzle brake having the correct 12 gas slots fully opened out without any cleanup required. There is a minor issue with the muzzle brake not having the two small locking screws which could be added for additional detail.
The overall length and diameter of the barrel/muzzle brake matches exactly to a set of 1:35 plans in the 7/1988 edition of Panzer Magazine as well as to enlarged 1:72 plans in the 4/2001 issue of Tank Master Magazine.
Unfortunately fitting the barrel to the DML ISU-152 kits is not so straightforward as the kit barrel is undersized being too narrow in diameter by about 1.5mm at the breech end and short in length by about 3 mm making the RB Models barrel a worthwhile replacement. As a consequence the holes in the kit gun mantlet and mounting bracket are also too small to take the metal barrel.
This means you will need to carefully drill out the holes to accept the metal barrel which is not an easy task with the mantlet due to the steps in the mantlet profile leaving plenty of scope of disaster. But it's good that RB Model made the barrel the correct dimensions with no compromises to fit the incorrect kit parts.
Fitting the metal barrel to the new Tamiya ISU-152 SPG (kit #35303) is somewhat easier thankfully. The kit barrel is designed to fit into the internal gun mounting but the large locating pin is about 1mm wider than the pin on the RB barrel. All you need is super glue three strips of .5mm plastic strip to the RB barrel neck (top and both sides) and then fit this into the Tamiya gun mounting, there is a small locating tab on the inside of the kit gun mounting collar that also has to be removed with a sharp #11 blade.
The metal barrel then fits neatly into the kit gun mounting collar and you assemble the rest of the gun mounting and mantlet as per the kit instructions, all very simply.
Overall view of the RB barrel in the Tamiya ISU-152 kit
This set has the barrel and muzzle brake cleanly machined with the correct dimensions for a marked improvement over the older DML ISU-152 kit barrels.
There is some modifications required to add the barrel to the DML kits which needs some effort and care but the result is an improvement in barrel details.
The barrel can also be used on the newer Tamiya ISU-152 SPG (kit #35303) with only minor modifications.
Highly Recommended
See a comparison of available ISU-152 metal barrels
Thanks to Leo at LionMarc Model Designs who now carry the full range of RB Models barrels for the review set.