Expedient Homemade Firearms. BSP-SMG.
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Expedient Homemade Firearms
-1-
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1
1.. 1-1-11//44”” BBSSPP ttuubbee xx 1122
½
½
” ” lleennggtthh.. 2
2.. 2.2.55mmmm sstteeeell sshheeeett ((xx22)) 99--
¾
¾
” ” lleennggtthh.. 33.. 4040xx2200 xx 22..55mmmm ttuubbee.. 4
4.. 3434..9933xx 1155..8888 xx 11..66mmmm ttuubbee 5
5.. 2020gg xx 33//88”” sspprriningg sstteeeell.. 6
6.. 1/1/88”” sstteeeell ppllaattee.. 7
7..
¼
¼
” ” ““ ““ 88..
¼
¼
” ” ““ ““ 99.. 5/5/88””xx 1144gg sstteeeell sshheeeett.. 1
100.. 66mmmm ssttuuddddiinngg c
coonnnneeccttoorrs s xx 22.. 1
111.. 66mmmm ccaapp ssccrreewws s xx 44.. 1
122.. DDoowwelel ppiinnss,, 44 && 66 mmmm ddiiaa.. 1
133.. 11”” xx 11//88”” rroouunndd ttuubbee.. 1
144.. 3355mmmm ddiiaa’’ rrububbbeerr ssttoocckk.. 1
155.. 11
¼
¼
” ” xx½
½
” ” BBSSPP RReedduucceerr.. 1166..
½
½
” ” BBSSPP SSoocckkeett.. 1177..
½
½
” ” BBSSPP LLoocckk NNuutt.. 1188..
½
½
” ” BBSSPP TThhrreeaaddeedd TTuubbee.. 1199.. 11
¼
¼
” ” BBSSPP CCaapp.. 2200.. 1155..8888 xx 33.. 2255mmmm H
Hyyddrraauulliicc ttuubbee.. 2
E xp ed ie nt H om em ad e F ire ar m s. B S P -S M G -2 -
1. 15.88 x 3.25mm tubing. 2.
½
” BSP Socket.3.
½
” BSP nipple. 4.½
” BSP lock nut5. 1
¼
” x½
” BSP reducer. 6. Magazine Catch.7. Magazine. 8. Trigger. 9. Trigger Bar. 10. Bolt.
11. Sear.
12. Mainspring.
13. Stock anchor point. 14. 1” Diameter x 1/8” tube. 15. Rubber buffer.
16. 1
¼
” BSP pipe Cap.Expedient Homemade Firearms. BSP-SMG
-3-
T
T
E
E
M
M
P
P
L
L
A
A
T
T
E
E
S
S
(Internal Components. Hole Diameters Arrowed)
Sear.
1/8” Plate.
Trigger Bar.
¼” Plate.
Trigger.
¼” Plate
Magazine Well.
40 x 20mm Tube.
Trigger Guard.
14 gauge sheet steel.
Magazine Catch.
20 gauge
spring steel. Magazine Stop. 40 x 20mm Tube.
66
m
m
6mm
3.8mm
3.8mm 4mm
E xp ed ie nt H om em ad e F ire ar m s. B S P – S M G . -4 -
L
L
O
O
W
W
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
T
T
E
E
M
M
P
P
L
L
A
A
T
T
E
E
(Hole diameters shown in millimetres)
The lower receiver is composed of two receiver side- plates, each being 9¾’’ in length.
Each plate is identical. Each side - plate is cut from a length of 2.5mm thick steel sheet
to the shape of the above template. The square recess shown in figure ‘A’ is the anchor
point for the shoulder stock. This measures ½’’ square.
Note: If the template is not 9¾’’ in length when printed, it may be enlarged using a
photocopier until the necessary length is achieved.
9
¾
’’6mm 4mm 4mm 6mm
2.5mm steel Sheet.
E xp ed ie nt H om em ad e F ire ar m s. B S P -S M G . -5 -
L
L
O
O
W
W
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
A
A
S
S
S
S
E
E
M
M
B
B
L
L
Y
Y
To create the lower receiver assembly, the two receiver side- plates are joined together by spacing them between two 6mm studding connectors, (A and B). Four dome head cap screws are then screwed into the connectors and thoroughly tightened, effectively holding the assembly together. The two connectors must be exactly 20mm in length. As bought, 6mm connectors are usually this exact length, but if they are not, they may be trimmed on a lathe until the required length is achieved.
A section of steel plate measuring 20 x 20mm is now silver soldered between the two side- plates in the position shown at ‘C’ below. The plate should be
¼
” thick. A gap of 2mm should now exist between the plate and the end of the receiver.Top View Side View
STIDDING CONNECTOR ‘A’ STUDDING CONNECTOR ‘B’ 2.5
m
m
Exp
ed
ien
t H
omemad
e
Fir
ear
ms.
B
SP-SM
G
-6
-
E xp ed ie nt H om em ad e F ire ar m s. B S P -S M G -
7-L
L
O
O
W
W
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
:
:
W
W
E
E
L
L
L
L
A
A
N
N
D
D
G
G
U
U
A
A
R
R
D
D
F
F
I
I
T
T
T
T
E
E
D
D
The magazine well is inserted into the receiver and welded in place along points ‘A’ and ‘B’.
Note: Do not weld along opposite side of point ‘B’. It must be ensured before welding that
the top edge of the well is 7mm above the top edge of the receiver.
7mm B A C D 27mm 103mm 5/8
” Trigger Guard
9x7mm 3mm
The trigger guard is made from a 103mm length of 5/8” steel sheet. This sheet should be 5/8” wide. The guard is formed to the shape of the template on page 3.
Expedient Homemade Firearms. BSP-SMG
-8-
P
P
I
I
S
S
T
T
O
O
L
L
G
G
R
R
I
I
P
P
The grip is the next part to make.
It is made from a 112mm length of 40 x 20mm tubing.
A 5.8mm diameter hole is drilled through the grip in the position
shown in the accompanying grip template.
Before the grip is fixed to the receiver the sear must be made and
fitted. See page 8.
11
2m
m
5.8mm
Expedient Homemade Firearms. BSP-SMG
-9-
S
S
E
E
A
A
R
R
C
C
O
O
N
N
S
S
T
T
R
R
U
U
C
C
T
T
I
I
O
O
N
N
The sear is cut from a section
of 1/8” thick steel plate. See
templates, page 3.
A 4mm diameter dowel pin is
tapped into the sears 3.8mm
hole.
The pin should protrude 8mm
from the sears right side
when fitted.
The sear is made from mild
steel and should be case
hardened after final shaping.
4mm dowel pin TOP
Right Side
6mm
8mm
Sear-
Expedient Homemade Firearms. BSP-SMG
-10-
T
T
R
R
I
I
G
G
G
G
E
E
R
R
The trigger is made from a section of ¼” thick steel
plate. A 4mm diameter dowel pin (a spring pin could be
used as a substitute) is tapped into the 3.8mm hole.
The pin must protrude 6mm from each side of the
trigger when fitted.
4mm Dowel Pin
Rear
Rear View
Pin must protrude
Expedient Homemade Firearms. BSP-SMG
-11-
F
F
I
I
T
T
T
T
I
I
N
N
G
G
T
T
H
H
E
E
S
S
E
E
A
A
R
R
Before the sear is fitted, a slot is cut through the rear and
front of the grip wall. The slot is 15mm deep and 4mm wide.
The sear is inserted into this slot and retained with a 6mm
diameter dowel pin. This pin should be 20mm in length.
Grip
Sear Fitted5.8mm
Cut 4mm x 15mm Slot
R
ear
V
ie
w
Spring Fitted
The sear spring is formed from 20g spring wire to the shape illustrated opposite.
It should have between four and six coils.
Expedient Homemade Firearms. BSP - SMG -12-
G
G
R
R
I
I
P
P
A
A
S
S
S
S
E
E
M
M
B
B
L
L
Y
Y
F
F
I
I
T
T
T
T
E
E
D
D
The grip and sear assembly is in
serted into the receiver and
retained with two dowel pins.
The magazine catch is bolted to the front of the receiver using a 6mm diameter dome head socket screw.
Receiver Top
2.5mm
Note:
It is very important that
the top edge of the grip is positioned 2.5 – 3mm below the top
ed
g
e of the receiver.
Grip
E
xp
ed
ie
nt
H
om
em
ad
e F
ire
ar
m
s.
B
S
P
- S
M
G
-13
-
F
F
U
U
L
L
L
L
Y
Y
A
A
S
S
S
S
E
E
M
M
B
B
L
L
E
E
D
D
L
L
O
O
W
W
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
Expedient Homemade Firearms. BSP-SMG
-14-
P
P
H
H
O
O
T
T
O
O
O
O
F
F
U
U
P
P
P
P
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
C
C
O
O
M
M
P
P
O
O
N
N
E
E
N
N
T
T
S
S
The upper receiver assembly consists of a 1
¼
” BSP tube (screwed at both ends) and fitted with a Cap and Reducer, as photo ‘A’ below illustrates. Photo ‘B’ shows the reducer and cap screwed onto the receiver tube and the barrel assembly ready for fitting.‘A’
E xp ed ie nt H om em ad e F ire ar m s. B S P -S M G -15 -
U
U
P
P
P
P
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
T
T
E
E
M
M
P
P
L
L
A
A
T
T
E
E
The upper receiver template must be enlarged using a photocopier until it is 12
½
” in length.Once enlarged, the template is glued around the 1
¼
” BSP upper receiver tube. The recesses for the ejection port, magazine well (EP&MW), bolt handle, and sear can then be marked onto the receiver tube.12
½
”Exp
ed
ien
t H
omemad
e
Fir
ear
ms.
B
SP-SM
G
-16
-
U
U
P
P
P
P
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
S
S
H
H
O
O
W
W
N
N
W
W
I
I
T
T
H
H
T
T
E
E
M
M
P
P
L
L
A
A
T
T
E
E
BSP- 9mmSMG.
Expedient Homemade Firearms. BSP-SMG
-17-
P
P
H
H
O
O
T
T
O
O
O
O
F
F
T
T
E
E
M
M
P
P
L
L
A
A
T
T
E
E
A
A
T
T
T
T
A
A
C
C
H
H
E
E
D
D
T
T
O
O
U
U
P
P
P
P
E
E
R
R
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
T
T
U
U
B
B
E
E
Expedient Homemade Firearms. BSP-SMG -18- 12
½
” 1¼
” B SP Tubing Thread Length: 1
Expedient Homemade Firearms. BSP-SMG
-19-
The BSP nipple, socket, and lock nut assembly are screwed into the reducer. The assembly is then thoroughly tightened.
The barrel tube is inserted into the BSP barrel assembly.
A
Expedient Homemade Firearms. BSP-SMG
-20-
P
P
H
H
O
O
T
T
O
O
O
O
F
F
B
B
A
A
R
R
R
R
E
E
L
L
C
C
O
O
M
M
P
P
O
O
N
N
E
E
N
N
T
T
S
S
The barrel is assembled from a 9” length of 15.88 x 3.25mm
hydraulic tubing, a 1
¼
” BSP Reducer,½
” BSP Lock nut,½
” BSP Socket, and a½
” BSP Nipple (threaded tube).Screwing the barrel assembly onto the upper receiver. Hydraulic tube
Reducer Nut Socket
Expedient Homemade Firearms. BSP-SMG
-21-
B
B
O
O
L
L
T
T
A
A
S
S
S
S
E
E
M
M
B
B
L
L
Y
Y
The bolt is machined to the following dimensions from a
suitable section of round steel stock.
36
m
m
83mm
50mm
20mm
13.5mm
B
BU
UF
FF
FE
ER
R
A
A
N
N
D
D
S
SP
PR
RI
I
N
N
G
G
GU
G
U
I
I
D
D
E
E
The buffer is made from a section of hard rubber stock to
the following dimensions.
The spring guide is nothing more than a length of 1”
diameter tubing.
The tubing should have a wall thickness of 1/8”.
1” diameter tube (Spring Guide)
66mm
25mm
12
35 19
25
Expedient Homemade Firearms. BSP- SMG
-22-
A
A
L
L
T
T
E
E
R
R
N
N
A
A
T
T
I
I
V
V
E
E
B
B
O
O
L
L
T
T
C
C
O
O
N
N
S
S
T
T
R
R
U
U
C
C
I
I
O
O
N
N
M
M
E
E
T
T
H
H
O
O
D
D
An alternative to machining the SMG bolt would be to assemble it from the components illustrated below.
The components are fitted to the 8mm bolt section as shown below.
8mm bolt section and nut
‘J’ / Hook bolt
Expedient Homemade Firearms. BSP- SMG
-23-
The ½” spring pin is two inches in length and is silver soldered to the end of an 8mm diameter high tensile bolt. The end of the bolt section being fitted with the firing pin prior to this.
A stack of 1 ½” diameter washers (with 8mm holes) are then inserted over the bolt section and retained with a nut.
Expedient Homemade Firearms. BSP-SMG
-24-
F
F
I
I
T
T
T
T
I
I
N
N
G
G
T
T
H
H
E
E
M
M
A
A
I
I
N
N
S
S
P
P
R
R
I
I
N
N
G
G
After placing the bolt into the upper receiver, the mainspring
can be inserted, followed by screwing on the BSP cap.
Expedient Homemade Firearms. BSP-SMG
-25- Magazine Template
A 34.93 x 15.88mm plastic tube cap is used to seal off the bottom of the magazine.
Drill two 2mm diameter holes through the
Magazine body and cap to retain the cap in position.
The m
ag
az
in
e body is 9”
in lengt
h. If
it
is not
this leng
th w
hen
pr
int
ed
, t
he t
emplat
e sho
uld be enlar
ged using a pho
tocopier
unt
il t
his measur
em
ent
is achieved.
The t
emp
lat
e is at
tached t
o a l
en
gt
h of
34.93 x 15.88mm t
ubing.
Expedient Homemade Firearms. BSP-SMG
As shown in Expedient Homemade Firearms -The 9mm Sub-Machine Gun, the magazine is made from a section of 34.93 x 15.88mm
rectangular tubing.
As a design improvement i have added a plastic tube cap, retained with two pins, to act as the magazine base plate.
Expedient Homemade Firearms. BSP-SMG
-27-F
F
I
I
T
T
T
T
I
I
N
N
G
G
A
A
S
S
H
H
O
O
U
U
L
L
D
D
E
E
R
R
S
S
T
T
O
O
C
C
K
K
I
I
t
t
i
i
s
s
q
q
u
u
i
i
e
e
t
t
p
p
o
o
s
s
s
s
i
i
b
b
l
l
e
e
t
t
o
o
c
c
o
o
n
n
s
s
t
t
r
r
u
u
c
c
t
t
a
a
s
s
i
i
m
m
p
p
l
l
e
e
f
f
o
o
l
l
d
d
i
i
n
n
g
g
s
s
h
h
o
o
u
u
l
l
d
d
e
e
r
r
s
s
t
t
o
o
c
c
k
k
f
f
o
o
r
r
t
t
h
h
e
e
B
B
S
S
P
P
m
m
a
a
c
c
h
h
i
i
n
n
e
e
g
g
u
u
n
n
u
u
s
s
i
i
n
n
g
g
n
n
o
o
t
t
h
h
i
i
n
n
g
g
m
m
o
o
r
r
e
e
t
t
h
h
a
a
n
n
a
a
m
m
o
o
d
d
i
i
f
f
i
i
e
e
d
d
3
3
/
/
8
8
”
”
r
r
a
a
t
t
c
c
h
h
e
e
t
t
s
s
p
p
a
a
n
n
n
n
e
e
r
r
a
a
n
n
d
d
a
a
l
l
e
e
n
n
g
g
t
t
h
h
o
o
f
f
s
s
t
t
e
e
e
e
l
l
t
t
u
u
b
b
i
i
n
n
g
g
!
!
T
T
h
h
e
e
f
f
o
o
l
l
l
l
o
o
w
w
i
i
n
n
g
g
p
p
a
a
g
g
e
e
s
s
i
i
l
l
l
l
u
u
s
s
t
t
r
r
a
a
t
t
e
e
h
h
o
o
w
w
t
t
h
h
i
i
s
s
i
i
s
s
d
d
o
o
n
n
e
e
.
.
F
Expedient Homemade Firearms. BSP - SMG
-28-
P
P
H
H
O
O
T
T
O
O
O
O
F
F
S
S
H
H
O
O
U
U
L
L
D
D
E
E
R
R
S
S
T
T
O
O
C
C
K
K
C
C
O
O
M
M
P
P
O
O
N
N
E
E
N
N
T
T
S
S
The shoulder stock is assembled from a 3/8” ratchet spanner, a length of
5/8” round tube, a section of
½
” box tube, four washers, a cotter pin, andExpedient Homemade Firearms. BSP-SMG
-29 -
A
A
S
S
S
S
E
E
M
M
B
B
L
L
I
I
N
N
G
G
T
T
H
H
E
E
S
S
H
H
O
O
U
U
L
L
D
D
E
E
R
R
S
S
T
T
O
O
C
C
K
K
M
M
A
A
T
T
E
E
R
R
I
I
A
A
L
L
S
S
R
R
E
E
Q
Q
U
U
I
I
R
R
E
E
D
D
1. 3/8” ratchet spanner. 2. 5/8” x 16g steel tube.
3.
½
” x 16g box section tube.4. 1
¼
” washers x¾
” hole. 5. Cotter pin x 1.3/8” Ratchet spanner.
The ratchet spanner is cut down and shortened until it has an overall length of around 4 – 5”.
½
” tubeInsert tube onto ratchet and retain using high strength bearing adhesive.
4- 5”
Slide washers onto tube.
A series of washers are placed
over the
½
” box section. Thesemay consist of either four
standard ‘light’ washers or two to three thick ‘heavy’ washers. Either way, the stack of
washers must result in a combined length of 4 – 5mm.
Expedient Homemade Firearms.
BSP-SMG--30-
R
R
E
E
A
A
R
R
V
V
I
I
E
E
W
W
O
O
F
F
W
W
E
E
A
A
P
P
O
O
N
N
S
S
H
H
O
O
W
W
I
I
N
N
G
G
S
S
H
H
O
O
U
U
L
L
D
D
E
E
R
R
S
S
T
T
O
O
C
C
K
K
A
A
T
T
T
T
A
A
C
C
H
H
E
E
D
D
T
T
O
O
R
R
E
E
C
C
E
E
I
I
V
V
E
E
R
R
Upper
Receiver
Insert cotter pin
into hole to hold
shoulder stock
in place.
Shoulder Stock
Expedient Homemade Firearms. BSP-SMG
-31-
S
S
H
H
O
O
U
U
L
L
D
D
E
E
R
R
S
S
T
T
O
O
C
C
K
K
T
T
h
h
e
e
c
c
l
l
o
o
c
c
k
k
w
w
i
i
s
s
e
e
a
a
n
n
d
d
A
A
n
n
t
t
i
i
-
-
c
c
l
l
o
o
c
c
k
k
w
w
i
i
s
s
e
e
s
s
e
e
l
l
e
e
c
c
t
t
o
o
r
r
s
s
w
w
i
i
t
t
c
c
h
h
.
.
The selector switch is rotated either clockwise or anti-clockwise to allow the stock to be extended or closed; in just the same manner as if undoing a nut or bolt !