A NEW Butt for your Mk5 Sten

[Peter Laidler]

By Peter Laidler
With thanks to Vincent from the forum and Brian (at BDL Ltd)

So you want or need a new butt for your Mk5 Sten gun do you? Well, there’s several ways that you can do it. You can patch-up what you have for that real authentic been there – done that look or you can buy another – if you can find one, make yourself another or better still, and cheaper, you can convert a No4 rifle butt to suit. The old Sten EMER’s tell us how to do this but they don’t tell the whole story. So here I’m going to do it for you........ First you can only do this properly by using a BANTAM butt. This is because the angular geometry at the comb of the butt at the knuckle area is only correct when we use a Bantam butt. And yes, a No1/SMLE bantam butt is also suitable too


A new No4 bantam butt, still in the wrapper. An ideal start point


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Opened for the first time in 50 years, our soon to be new Sten butt


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(You CAN use a longer butt, but if you do, you’ll have to build up the new top front of the ‘new’ Sten butt with a patch. I won’t go into it but think Pythagoras – angles, lengths etc!)

Having got your new or undamaged bantam butt the first thing to do is to cut it off 10” from the rear end of the stockbolt hole. It is MOST important to cut the butt off exactly square length and crosswise to the stockbolt for obvious reasons. I set this one up in a lathe because the s/b hole can be centred in the tailstock while the chuck will grip the butt socket part which is conveniently round and concentric to the axis of the s/b hole. Spin slowly and cut exactly square. Simple isn’t it? Keep this old socket because we’re going to need it soon......

Our butt conveniently centred in the lathe chuck ready to be cut exactly square to the line of the stock bolt


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Where were we now..... Ah yes..... Mark ½” down from the cut off end a line and using the old Mk5 Sten butt socket attached to the stock bolt brought down centrally onto the new cut surface, mark the oblong shape of the new socket. Carefully cut this shape down to the ½” depth previously marked. There isn’t a lot of meat left at the top and bottom edges so make sure that the socket is marked centrally. Carefully cut back to ½” and file/rasp to a tight fit in the socket.

The butt socket fitted to the new butt. Make sure that this is square-on and a tight fit.

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From a suitable position down the length of each side of the butt, plane, rasp or file the butt to a slight taper forwards to end with a 1/8” or so step at the new butt socket.

Slimming the butt down forwards to mate up with the Mk5 socket. Repeat on both sides of course!


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Now set about cutting the knuckle of the butt off to make the underside of that area a straight line from front to rear but DO NOT run into the new socket area. Keep this piece of knuckle wood because we’re going to use this wood to infill patch the redundant sling loop plate recess 4” or so to the rear. Same wood is the BEST wood for your colour match!

This piece of wood cut from the knuckle shapes the butt from a No4 rifle to a Mk5 Sten. It is the ideal piece to patch-in the now redundant underside sling loop plate recess

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Using this knuckle wood, patch the sling loop plate recess and while you’re there, carefully cut out a NEW sling loop plate recess at the top of the butt as shown in the photographs that accompany this article. You’ll now see the distinct shape of your new Mk5 Sten butt taking place.

The plate recess plugged and made off. The perfect fit and match! New top mounted sling loop recessed and plate fitted

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All that is left to do now is to make good all the cut, rasp and file marks. Do this by using a good wood scraper along the grain slowly and carefully, taking oput all the ridges and high spots while rounding off the top and bottom sides to suit. Finally adjust the fit of the butt into the Sten socket and chamfer/adjust to suit – and there you have it. A new butt for your Sten.

There it is, sling loop and butt socket fitted, cleaned down and dosed in linseed

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But that’s not quite all – yet! Because the butt is now shorter, the old stockbolt will be slightly longer and therefore protrude forwards by approx 1.2”. You can do one of two things now. You can turn the thread back by that amount and cut the bolt short to suit - or you can insert a wooden spacer into the hole. And guess what........ you already have a spacer half completed in the form of the front end of the butt you cut off........ and it’s probably still mounted in the lathe chuck too! Turn this down to the diameter of the stockbolt hole in the butt and cut it off approx 1.2” long. There’s your spacer! It gets better too because the step between the bolt head and shaft in the hole contracts slightly (to hold the flat washer tight) and this slight crimp is going to hold your wooden spacer tight. You probably won’t be able to get the flat washer out so just forget it and insert another.

The wood spacer 1.2” long machined from the remains of the old butt socket you cut off! Good isn’t it!

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There, a new butt from E-Bay approx £40 (ask me for details if you need one) or a new converted one for £25 or so plus your own time and satisfaction

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