British 4.7"/45 (120mm) QF Marks IX and XII Barrels

Published: February 13th, 2016     
Product Image
Reviewed by: Luke R. Bucci PhD - IPMS# 33549
Scale: 1/700
Company: Master Model
Price: $5.00
Product / Stock #: SM-700-042
Product provided by: Master Model

Thanks to Master-Model for the barrels and IPMSUSA staff for handling the request and publishing this review.

Bottom Line

Master-Model supplies the ultimate barrels for 4.7in/45 (120mm) main guns for most WW2 British destroyer classes.

Master-Models of Poland is rapidly producing almost all barrels for guns larger than four inches from the major navies of WW2 and most modern navies too. This barrel set fills a gap long needed for British Royal Navy destroyers. Very timely as more and more 1/700 scale WW2 Royal Navy destroyers are finally appearing. The British Mark IX and XII QF 4.7inch/45 caliber (120mm/45) guns were the most common destroyer main gun for British destroyers from 1930 until non-emergency classes appeared in 1943. They are listed as QF (Quick Firing) relative to earlier Mark WWI versions since they used a single brass cartridge instead of shells and silk powder bags. Mark IX 4.7in guns were used in single mounts and Mark XII guns were in double mounts. Note there were different 4.7in guns used for L & M class destroyers (Mk XI), and Nelson class battleships, older carriers and auxiliaries (Mk XIII). Master-Models barrels were not identical to Mk XIII appearance but at 1/700 scale could be used without realizing any differences.

These 4.7in guns equipped Royal Navy destroyer classes A-I, O and Q-W & Z in single mounts (Mk IX), and J, K, N and Tribal classes in double mounts (Mk XII). Single mounts were also used on sloops, submarines, depot ships and Abdiel class minelayers. These guns were intended to be dual-purpose (used against surface and aircraft targets), but low elevation of mounts (40 degrees) limited their usefulness, and they were replaced by 4.5inch guns in later classes of destroyers.

What You Get

A small card wrapped in plastic with a plastic bag inside containing a smaller bag with eight very small brass barrels and an instruction sheet, with a header card stapled to the card identifying the type of barrels. Eight barrels is enough to equip two A-I, O, Q-W & Z class WW2 Royal Navy destroyers or one J, K, N or Tribal class destroyer.

The barrels are very small and thinner than most plastic models' 20mm barrels, including the old Skywave O class kits they are appropriate for - in other words, they are very close to actual 1/700 scale. They are free from flash or defects, and have the bore drilled out, unlike plastic barrels. Their taper and appearance are accurate according to Campbell's Naval Weapons of World War II (pp. 48-51).

Instructions are very simple and describe the 0.3 drill bit needed without explaining what 0.3 means. You simply cut off the plastic barrel, clean up the insertion area with a sharp hobby knife, drill a hole and glue the brass barrel with cyanoacrylate (CA) glue. The ship classes using these barrels are listed - a big help. Another big help is the option to drill the hole at an angle so the barrel can be elevated to your desire.

The Build

Two old Skywave SW-350 O class destroyers built OOB in the 1980s were perfect candidates for these barrels as an upgrade. However, since the brass barrels are to-scale, the other weapons would have to be replaced, and might as well add other photoetch upgrades too or else the new barrels will be less impactful. Also, the paint schemes were done before resources were available to accurately portray these ships, meaning a complicated strip and repaint procedure or ugly overpainting. So their refurbishment will wait for another time.

An unbuilt Skywave O class British destroyer lying around for decades was dusted off for build with these barrels and updated with photoetch sets purchased earlier. One of the previously built O class models will get the new brass barrels without refurbishment. I did not attempt to replace 4.7in Mk XII barrels in twin mounts. These mounts were more open (at least for Matchbox K class kits and White Ensign aftermarket mounts) and would mean cutting off and sanding the brass barrel mounting tab to be flush with the cut plastic barrels. This operation is tricky.

As usual, I first washed the barrels - individually and very carefully - and the Skywave O class sprue in warm water with detergent. Other WW2 Royal Navy photoetch sets were likewise opened and cleaned. This time, the O class kit was built as HMS Onslow to modern standards using photographic references, photoetch parts and scratchbuilt parts. White Ensign Models WEM-720 (1/700 Royal Navy WW2 A/A Weapons) and WEM-721 (1/700 "O" and "P" class Destroyers) sets were used to refurbish HMS Onslow, the most famous O class destroyer. Onslow was chosen in 1942 fit, since it had the most evidence on appearance, and mostly matched the kit pieces (especially masts and AA fit). Skywave O class molds are well-known to be close but not accurate, especially for the forward superstructure, but I did not modify the superstructure substantially. However, many modifications to the kit parts were made. Plastic and brass rod, plastic strip, drafting paper, wine cap foil and spare pieces were widely used to more closely approximate actual appearance. Portholes were drilled out on hull and superstructures, and the bridge top reworked. Deck fittings were removed and replaced with PE or scratchbuilt pieces.

Focusing on the Master-Model brass barrel review, the 4.7in mounts were sanded to remove seams and out-of-register molding, resulting in a more accurate appearance of the shield. Breeches were removed and rears of mounts were drilled out and sanded to produce an open, shielded mount. Previously built O class models simply had the rear end painted black to simulate the open rear of these mounts. The plastic barrel was cut off, and the stump removed with a sharp hobby knife with a #11 blade. My smallest diameter pin vise drill bit was used, probably #86, to drill the hole for mounting the brass barrel. I gave each mount an elevation of 10-20 degrees or so. The insertion part of the brass barrel was long, and a small portion was cut off to ensure the barrel end was flush with the mount. The breech and extra plastic rod were reglued to the inside of the mounts to line up with the elevation of the brass barrels. WEM-721 PE breeches were placed over the plastic breeches.

See photographs for comparison of Master Model 4.7in barrels to the other kit barrels. As was typical in earlier 1/700 scale warship models, the light AA barrels were as thick or thicker than the main armament barrels, as is true for the Skywave O class kit. Master-Model brass 4.7in barrels looked much better than the original kit pieces, even after the kit barrels were sanded to remove seams and flatten the round-tip muzzle. Master-Model barrels give the HMS Onslow an accurate look - so accurate that the kit benefits from replacing other out-of-scale parts, especially (at least) other weapons.


Few other British Navy 4.7in barrel sets are available (Flyhawk has Mk XII barrels, but at a higher price and their appearance does not match actual). Other plastic and resin 4.7in Mk IX or XII barrels are part of mounts, but do not have the same quality, appearance or accurate diameter. They are frequently off-register and have seams and round tips. Master-Models makes a 4.7in/40cal set of barrels but these are the low angle WWI variety used in Nelson and Courageous classes, not smaller ships. Thus, Master Model British Navy 4.7in barrels are the only option for replacing kit barrels, are excellent, and are not expensive.


Master-Model has done it again! British destroyers are now ready for accurate and to-scale main gun barrels. Good value, accurate scale and appearance and drilled out bores make ships with these barrels ultimately upgraded. At $4-5, the value is excellent - about $0.50 per barrel or $2 per ship for single mount destroyers or $4-5 per dual mount ships.


  1. Accurate and correctly sized.
  2. Instructions list ship classes using these barrels.
  3. Simple to replace plastic kit barrels, less so for some twin mounts.
  4. Can elevate main guns if desired - finally!


  1. Small size means delicate handling needed. These are easily bent.
  2. Accurate size means other original kit parts need to be replaced or the 4.7in barrels will look puny.

Recommended for superdetailers and advanced modelers of 1/700 Royal Navy destroyers because these are small parts and need small tools and a delicate touch. Brass barrels accuracy also necessitates replacing plastic guns of smaller calibers with photoetch versions at least, meaning a more complicated build than OOB (extra aftermarket/photoetch sets and more advanced skills). Very highly recommended!


  • Figure 1: Master-Model SM-700-042 Brass Barrels Set for WW2 British Navy 4.7in/45cal Mk IX & XII guns, used mostly on fleet destroyers.
  • Figure 2: Master-Model 4.7in/45 Mk IX/MkXII Master-Model barrels.
  • Figure 3: Master-Model SM-700-042 Brass Barrels Set Instruction Sheet
  • Figure 4: Comparison of Skywave O Class kit barrels with Master-Model 4.7in barrel. From left to right: 1) kit 4in AA gun barrel; 2) kit 4.7in mount with Master-Model 4.7in brass barrel; 3) kit 4.7in barrel removed from mount; and 4) 20mmx1 AA gun. Note that the 20mm barrel was as thick as the 4.7in kit barrels. Kit barrels were 3-4 times thicker than Master-Model brass barrels.
  • Figure 5: Comparison of both forward 4.7in mounts with plastic and brass barrels on finished models. From top to bottom: 1) HMS Onslow with Master-Model brass barrel - newly constructed; 2) HMS Onslaught with original kit barrels replaced with unpainted Master-Model barrels; 3) HMS Offa with original kit mounts and barrels. Onslaught and Offa were built out-of-box with little or no prep of pieces in the early 1980s. Please pardon their appearance.
  • Figure 6: HMS Onslow from Skywave SW350 kit with Master-Model SM-700-042 4.7in/45 MkIX brass barrels and numerous photoetch and scratchbuilt parts.
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    Figure 6

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