Lewis Gun: Build 2

At the end of the last build post, I had made the bipod legs but not the bipod itself. I designed the bipod leg mounts and assembled them. I missed out the hinge on the cut list (something has to be missed out, it’s Sod’s law) so had to hand-make them.

The distinctive bands at the front of the Lewis cooling jacket are welded into place. The rear one will also house the bipod unit made previously.

The rear sight block is another piece of laser cut steel, welded into place at the back of the receiver. I’m going to braze together the sight leaf itself together and use a 3D printed aperture to give elevation adjustment. (P.S.: Yes to other welders this weld is obviously pretty dire, I literally ran out of gas on this seam, I’ll clean it up).

The donor is held in by two screws pinching it from either side…

And a plate that will be welded into place at the back that holds under the buffer tube mount on the AEG.

I brazed together the parts for the rear sight leaf. The aperture is adjustable and is based on an ‘upgrade’ Lewis sight that gave a clearer field of view in low light conditions. The flat spring underneath locks it into upright or stowed positions.

The foresight is also 3D printed, this was by far the simplest way to get the weird shapes around that front post. This is secured by a screw and will be painted up to match the rest.

The buttstock is quite a simple one, secured by machine screws running through from one securing tang to the other. Once shaped it will be stained and finished with hardwax oil.

At the front end, the 3D printed cooling fins have arrived. They fit well, once painted up they will serve very nicely for the detailing purpose they are designed for.

Painting up and assembly under way, I have to touch up a couple of areas previously missed.

Once painted up, you can appreciate the sinister, gaping mouth of the cooling jacket.

Finished photos to follow!

If you are interested in the history of the Lewis, you can check out the introduction article here.

If you like this project or have an idea of your own, drop us a line on enquiries.vintageairsoft@gmail.com to discuss. ‘Like’ our Facebook page or follow the blog to get regular updates on projects and interesting videos and articles.

Don’t forget you can buy our complete products via Etsy.

Lewis Gun: Build 1

The base gun for this build is an M4. Nothing too fancy, but with lots of options for upgrade parts if needed. The first step to making the transformation into a Lewis is to build the receiver. I have modified plans I was given some time ago to build a replica to take the donor and be made from steel.

Inside this I will fit a ‘harness’ to hold the donor.

The drum magazine, on this I’m not sure if it will be functional, but it will be removable so I may do a very high capacity magazine in the future.

The external detailing is welded on.

I designed this spacer to mount on the rails, there are two of them to steady the barrel shroud.

 

Dry fitting the parts, you can see the space where the rear end of the cooling fins are to go.

I’m also making use of 3D printed parts for the taper on the fore-end. This part was simply much too big to make on the lathe and this system keeps the cost and the weight down.

The bipod is the next major component. It will need some feet, and hinges made up for the top, which will have to come in a later instalment.

Also for the next instalment, the design for the back of the cooling fins is complete (a long day’s work making this!) and it will be 3D printed much like the spacers before being painted to look like aluminium. It may even be a project for the new furnace.

 

If you are interested in the history of the Lewis, you can check out the introduction article here. 

If you like this project or have an idea of your own, drop us a line on enquiries.vintageairsoft@gmail.com to discuss. ‘Like’ our Facebook page or follow the blog to get regular updates on projects and interesting videos and articles. 

Don’t forget you can buy our complete products via Etsy.

Lewis Gun: Introduction

Before I go any further, if you are seriously interested in the history and workings of the Lewis gun, check out C&Rsenal’s video. If you just want a quick overview, you can skip that and carry on reading…

Issac Newton Lewis, Colonel, US Army designed his machine gun in 1911 and spent around two years banging his head against a brick wall trying to persuade the US Ordinance Department to adopt his gun. In 1913 he left the United States and set up shop in Belgium where he received a respectable first order from the Belgians. In 1914 BSA bought a license to produce it and as war loomed Lewis moved his factory to Britain to keep it out of German hands. Lewis’ BSA license proved very profitable: between BSA and Savage Arms around 50,000 Lewis Guns were produced by 1918 and the license granted him commission on every one made.

The design itself was based on work done by Samuel Maclean, but between Lewis and designers at BSA it was transformed into a reliable and easy to produce machine. It is gas operated, open bolt with three locking lugs at the rear of the bolt. The most distinctive feature is of course the massive aluminium heat sink/fins/barrel jacket arrangement.

Shot of the Lewis receiver. On the right you can see the barrel jacket and the rear end of the cooling fins. On the bottom of the gun, forward to the trigger is the clock-type main spring.

The idea of this was to wick heat away from the barrel as quickly as possible (quick-change barrels weren’t really a thing yet). The large mass of aluminium took the heat into the fins and the muzzle blast would suck air through from the back towards the front. In theory. In reality the necessity of this sophisticated arrangement is dubious, aircraft Lewis Guns were pressed into service on the ground during WWII, even in North Africa and the guns were found to function perfectly well without.

The magazine is also worth mentioning, coming in 47 and 97 round versions. This Pan magazine is NOT a drum magazine (which relies on a spring to feed, keeping ammunition aligned with the bore) and is manually rotated and indexed as the gun operates.

The indexing system for the Lewis. If you want to know how it works, see the C&R video above for the animation.

Last but not least, the mainspring is a spiral clockwork type, mounted in that distinct protrusion from the belly of the receiver. This is very efficient and saves space over a much larger conventional mainspring, also allowing for easy adjustment to account for field conditions to make for reliable firing in all weather.

 

The Lewis gun’s service was long and varied. Before even leaving for Europe, Lewis had put the gun on a Wright Flyer and as a result it has the distinction of being the first machine-gun fired from an aircraft (1912).

During the Great War, Britain used them extensively, eventually outnumbering the Vickers by about 3:1 in spite of being more expensive. That the government was willing to spend so much more on these than an established home-grown piece is a comment on the quality of the design.

Due to its light weight, the Lewis was readily adopted by Air Arms where it was widely used for observer’s defensive guns. It was also mounted as foreward firing guns but had to be mounted outside of the propeller’s arc due to firing from an open bolt (therefore being nigh-on impossible to synchronise to a propeller).

By the Second World War, the Lewis was outdated for the role in which it was originally used. After Dunkirk and the fall of France, Britain pulled its Lewis guns out of reserve where it was used by the Home Guard and for low-level anti-aircraft fire. In the Far East it served with Empire forces on the front lines. Throughout the war it remained in use with the Navy and RAF for air defence from boats.

 

As well as versions chambered in .303 British, there were Lewis guns made in 7.92 and 7.7 Japanese rimmed, the Japanese having copied the design from versions captured in the Far East.

 

The Lewis had some limited influence on other designs, the FG42 taking inspiration for its bolt/piston arrangement and from that the M60. There was also a Lewis pistol, which fired from an open bolt.

 

Links:

Lewis gun firing in slow motion

Lewis Gun video, manuals and pictures

The Lewis Pistol