SELECT FIRE
10/22
By Wayne Thornbrugh
The TEK Full Auto Conversion
229
SELECT FIRE
10/22
By Wayne Thornbrugh
W ft
The TEK Full Auto Conversion
Desert Publications
El Dorado, AR 71731-1751
I
Select Fire
10/22
By Wayne Thornbrugh
©1985 by Desert Publications
P.O. Box 1751
El Dorado, AR 71731
501-862-2077
ISBN #:0-87947-229-4
109876543
Desert Publication is a division of
The DELTA GROUP, Ltd.
Direct all inquires & orders to the above address.
All rights reserved. Except of use in a review, no portion of this book
may be reproduced by any means known or unknown without the
expressed written permission of the publisher.
Neither the author nor the publisher assumes any responsibility for the
use or misuse of the information contained in this book.
ii
Table Of Contents
Foreword 1
Which Configuration Is Best, The Front
Mounted Bolt Arrest or Or The Rear? 3
Fitting The Auto-Sear Trip Tolerance 5
Full Auto Operation— Rear Mounted Arrestor 17
Fitting Rear Arrestor To Bolt Clearance 23
Fitting Front Mounted Arrestor To Bolt Clearance 33
111
WARNING
Since the Hughes' Amendment, which went into effect on
May 1 9, 1 986, it is no longer possible for civilians to do Form 1
conversions or manufacturing of machine guns. Also, Class II
manufacturers can no longer produce machine guns for
civilian consumption.
This book is produced and sold for academic purposes only.
Since the original text of this book was written before the
above date, some of the text may be interpreted otherwise.
Let this warning emphasize that the actual production of a
machine gun by a civilian would be in violation of Federal Law!
IV
FOREWORD
The designs offered herein are not the brain-
child of a great gun designer but the stubborn
persistence of a retired military ordnance man
who undertook the project simply because they
said it couldn't be done. The project developed
into a small Class II manufacturing business
which sold the converted 10/22's in most of the
states where they are legal to own. To date, after
at least 100 thousand rounds fired, we have yet
to have a parts failure, Ruger's or our own.
After the final development of the first three
prototypes, we started a record of rounds fired,
which gun and what ammunition. After thirty
thousand rounds we quit keeping records
because all major brands seemed to work
equally well except for residue, grease and wax.
C.C.I, ammunition seems to burn cleaner and
leave less residue than all the others. So, for that
reason we must recommend their product.
Hardly a day goes by that we do not receive a
letter or phone call from someone who wants to
roll their own. In our supply / demand economy
someone will usually step forward to fill a void
sensed by the public. 1 believe this book will fill
that void, otherwise, neither the publisher nor I
would have undertaken the task. We both hope
you concur.
It is not difficult to design a drop-in automatic
sear, to trip it and bypass the trigger sear to
allow the 10/22 to, theoretically, cycle auto-
matically. Many hobbyists, gunsmiths and
Class II manufacturers have attempted to
convert the Ruger 10/22 to closed bolt, select
fire since 1 964, when Bill Ruger placed it on the
market. None, to my knowledge, have worked
with any degree of reliability. Most have not
and will not work, period!
The first step towards solving any problem is
recognizing the fact that there is one and what it
is! The answer to converting the 10/ 22 to select
fire is solving the problem of bolt bounce. In
counter-recoil the 10/22 bolt will bounce
upwards of 3/ 16" after striking the breech face
of the barrel. This allows the hammer to expend
its energy on the bolt rather than the firing pin.
With the bolt just .025 out of battery, the bolt
will block the hammer from the firing pin due to
the angle of attack. This is, in reality, a safety
feature as well as a method to prevent easy
conversion of the gun to slam fire. Bill Ruger
knew exactly what he was doing when he
designed the 10/22.
Plans, and in some cases parts, have been
available to convert the 10/ 22 to closed bolt,
1
SELECT FIRE 10/22
select fire, but by and large they have over-
looked the problem of bolt bounce or con-
veniently ignored it for the sake of commerce.
Others have given up on a closed bolt system
and designed elaborate open bolt systems.
An open bolt system for the .22 rimfire
cartridge in any configuration is unsatisfactory
simply because the cartridge case does not lend
itself for an open bolt mode. In the open bolt
mode the firing pin must precede the bolt, be it
fixed or pivoted. This allows the firing pin to
make contact with the rim of the case which
holds the priming mixture before the bolt is
fully closed and any way you cut it, this
amounts to headspace— excessive headspace.
This is why you get all those ruptured cases and
a face full of burnt powder and gas if you are a
left-handed shooter. Needless to say, repeated
stoppages are in order. The action is quickly
contaminated with powder residue due to its
being blown out the wrong way!
Firearms in .22 rimfire caliber have, for over
1 00 years, suffered from the toy or plinker
stigma. The average shooter will accept mediocre
ammunition, cheap and unreliable accessories
but, above all, the poor guy will lay out more
money than he did for the gun for a couple of
high capacity magazines only to have few work
properly! Does he complain to the manufacturer
or request a replacement or refund? No, he
simply clears the stoppage and accepts it as the
nature of the beast. It doesn't have to be that
way! This same shooter w ould in no way accept
this performance in his hunting rifle nor would
a law enforcement officer accept this perform-
ance from his service arm.
There is a 50 round magazine available that,
with some modifications and testing, can be
made 98 to 99% reliable and that's pretty good
odds. A self -addressed stamped envelope to the
author will bring you up to date on the care and
feeding of aftermarket magazines.
Wayne Thornbrugh
14615 Hwy. 12
Orofino, ID 83544
2
Which Configuration Is Best, The Front
Mounted Bolt Arrestor Or The Rear?
We believe there is a place for both and that
you must make the choice based upon your
needs and your capabilities. The rear mounted
arrestor is easier for those with limited tools.
We developed the rear mounted system with the
do-it-yourself builder in mind because there is a
milling operation involved on the bolt in the
front mounted system. Although the operation
is simple, you still must have a milling machine
or access to one.
We have fired over 10 thousand rounds
through our rear mounted arrestor prototype
with no stoppages (magazine failures excluded).
You should be aware, however, that the arrestor
is actuated, both lifted and lowered, by spring
pressure. Conceivably, if the mechanism became
contaminated enough with grease, wax. dirt
and powder residue, the spring action which
lowers the arrestor might not be great enough to
overcome the added friction.
In our testing this did not happen. However,
we disassembled the gun for cleaning and
inspecting every few hundred rounds. Antici-
pating that the lowering of the arrestor could
possibly be a problem with an extremely dirty
gun, we ran a test of 100 rounds fired with a
locked arrestor, allowing the full blow back
force of the bolt to be taken by the arrestor lug.
Nothing came apart, no damage was done
except a very slight marking of the bolt and a
very small upsetting of the arrestor lug surface.
In the front mounted bolt arrestor system the
arrestor is cammed down by the positive action
of the hammer mounted cam-down pin. The
arrestor is free to fail on its own weight since all
spring pressure is removed before the hammer
reaches the firing pin, but there is not enough
time for this to happen since its speed of fall is
slower than the movement of the bolt. Hence,
the cam-down pin on the hammer for fast,
positive action.
If you have read this far and you think you
want to tackle the job, consider this: it cannot
be done and made to work with any degree of
reliability if you do not have access to a good
drill press. You must, also, have access to an
oven or torch for annealing and heat treating.
This can be done with a throwaway propane
torch if you have a good tip assortment. You
will need a quality dial indicating caliper to lay
out the hole locations in the trigger housing and
various parts. If you have a heavy duty drill
press, it can be equipped with an X & Y feeding
milling table and used for any required milling
operation.
3
SELECT FIRE 10/22
GENERAL NOTES:
Please read before beginning conversion.
1. Please wear adequate eye protection during all
operations, both machining and shooting.
2. There are 4 different variations which can be
used depending on your personal choice: The bolt
arrestor can be either front mounting type or a rear
mounting type. The modification to the trigger can
be done 2 ways. The simplest way requires your
trigger finger to exert some upward force at the time
the trigger is pulled. This causes full auto firing. A
normal, straight back pull fires semi-auto. A more
sophisticated modification features a select lever
that allows you a positive selection between full and
semi-auto.
3. You may substitute 3-48 socket head screws for
the 3-56. Obtain them all .250 long. You will need
one that length— the rest can be cut shorter.
4. Unless you are experienced at heat treating and
have a furnace you are probably better off to make
the necessary parts from flat ground mild steel and
case harden.
5. You will need an extra .125 dia x .960 long dowel
pin for the auto-sear. Use the Ruger ejector pin for
the auto-sear and use the new pin for the ejector.
6. There is a small lip on most of Ruger's trigger
housings where the trigger comes thru into the
trigger guard. Remove enough of this to allow free
movement of the select lever if you are building the
Model II mechanism.
7. There is no alteration to the ejector when using
the front mounted arrestor. The long arm of the
auto-sear spring is set behind the ejector pin. A
small rod with a notch filed in the end makes this
easy. The hammer mounted arrestor lifting spring
arm goes to the right of the long arm of the auto-sear
spring. In other words, from left to right; arrestor—
ejector— long arm of auto-sear spring— arrestor
lifting spring arm.
8. The sear surface of the auto-sear must be fitted
to the auto-sear notch of the hammer with enough
height to allow the trigger sear to move under the
original trigger sear cut in the hammer. There
should not be excessive clearance, otherwise the
hammer will fall too violently down onto the trigger
sear and over a period of time could cause damage
to the sear surfaces. Just enough clearance to allow
the trigger sear to move easily under the hammer
notch with no binding is what we re after. One good
way to determine this clearance is when the auto-
sear is pushed off by hand the top of the hammer will
move about 1/8" forward when dropping to trigger
sear engagement.
9. When using the front mounted arrestor, a .187
dia x .950 long slave pin must be used when
assembling the trigger housing to the receiver.
Assemble the trigger housing and all parts in place
using the slave pin to position the arrestor. Retract
the bolt 1/4 inch or so and place an empty .22 rimfire
case or equal space between the bolt face and
barrel. Place trigger housing in receiver and insert
rear receiver cross pin first. Insert front cross pin,
pushing out and replacing the slave pin. Do this with
action upside down and insert cross pins from near
and push thru, going away from you. This will
prevent binding. Caution: these are push fits, not
drive fits!
10. Where screws must be locked after fitting final
assembly, they can be either Loc-Tite or a binding,
female thread can be cut as follows: Using a starting
tap (longer taper) only partially tap, leaving a couple
of threads undersize so as to bind on the screw
threads. You might wish to practice this on a scrap
of metal before tapping the actual part.
11. When you are ready to test fire, first do it on the
workbench. WEAR EYE PROTECTION! Remove
bullet and powder from a few rounds and insert one
in the chamber. With the barrel in a padded vise and
the action upside down, it is easy to fully retract the
bolt, select semi orfull auto with the other hand and
let the bolt slam closed. Run several rounds thru and
inspect the firing pin indentations. The indentations
should show no discernible difference between
semi and full auto.
12. Unless otherwise noted, all dimensions are in
inches.
4
Fitting The Auto-Sear Trip Tolerance
Disassemble the hammer strut and spring.
Wind a spring from .029 spring wire to
temporarily replace the regular hammer spring
and reassemble. If you use the regular hammer
spring while adjusting the auto-sear it will
damage the sear surface since it has not been
hardened yet.
Assemble the bolt, cocking handle and recoil
spring into the receiver. Secure the barrel in a
padded vise, action upside down. Assemble the
hammer assembly and auto-sear with spring
into the trigger housing. The long arm of the
A full auto sear is shown here. Note that the tang has
a slight bend. A slight bend Is necessary during final
fitting. This adjusts the auto-sear to trip at just the
right time.
auto-sear spring is set behind the ejector pin.
Retract the bolt slightly and place an empty .22
case or something similar between the bolt face
and the face of the barrel in order to insure that
the position of the auto-sear trip pin is behind
the auto-sear tail.
Place the trigger housing in the receiver and
secure with the 2 receiver cross pins. Insert the
bolt stop pin into the receiver. Remove the
empty .22 case holding the bolt partly open and
place a .020 feeler gauge between the bolt face
and the barrel face opposite the extractor side
of the bolt but not deep enough to allow the
firing pin to strike the feeler gauge, otherwise
the firing pin will be damaged.
Holding the feeler gauge in place retract the
bolt to full recoil and ease it back towards
battery— easy does it, don't let it slam back into
battery. Ease it back all the way, maintaining
control with the cocking handle. You should be
able to feel when the trip pin on the bolt first
makes contact with the auto-sear tail.
Ease it on closed against the .020 feeler gauge.
If it trips you will hear the hammer fall. If it does
not trip, remove the feeler gauge and try again.
If it trips you are somewhere between .001 and
.020 from full battery position when the auto-
5
SELECT FIRE 10/22
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SELECT FIRE 10/22
7
SELECT FIRE 10/22
8
SELECT FIRE 10/22
I
.925
Hand wind around 1/8 rod secured
in bench vise.
AUTO-SEAR SPRING
Hand wound from .029 stock
9
SELECT FIRE 10/22
T
I
.390*
.112
.093 R
.093
1.030
.135
.150
r
.352
12SDIA PiVOT
PIN HOLE
.093
.218
.190
.500
.210
200
Scale: 2:1
AUTO-SEAR
* The height of the sear surface is machined
slightly high in order that it may be fitted to the
mating sear notch on the hammer during final
tuning.
T.E.K. auto-sears are made out of 0-1 oil
hardening flat ground steel flats (3/16 x 1/2
stock). If you wish to use the same it can
probably be found at a local tool & die shop in
small pieces. Otherwise, it normally comes in
18-inch lengths,
To heat treat, bring the piece to about 1,550
degrees F and quench in oil. Draw for at least 1
hour at 400 degrees F. You can use the kitchen
oven for this. NOTE: Do not heat treat until all
final tuning and adjusting is done.
10
SELECT FIRE 10/22
This photo of modified trigger housing reveals 3
things: The forward mounting pivot pin (A); The bolt
release lever (B) which replaces the original bolt
hold-open lever; The Mod II select lever (C) which Is
In the full auto firing position.
Trigger mechanism showing a Mod II select lever
Installed.
sear trips . Try to determine the clearance even if
it's very wide. In all probability you will have to
bend the auto-sear tail forward. Don't be afraid
to overbend because it's much easier to bend it
rearward since it's up against the hammer, but
to bend it forward it must be removed from the
trigger housing. If after bending, you find that
This photo shows the select lever moved into the
semi-auto firing position.
Modifications to the original bolt are shown here. An
auto-sear trip pin is added. The mill cut shown is
used with a forward mounted arrestor.
you have no clearance, bend the tail rearward a
little at a time until it falls within tolerance. A
small (4 inch) Crescent wrench is ideal to bend
the sear tail with. The auto-sear should trip
between .010 and .015. After breaking all sharp
edges (careful with the sear surface), the auto-
sear is ready to heat treat.
11
SELECT FIRE 10/22
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SELECT FIRE 10/22
13
SELECT FIRE 10/22
7/32 dia thru and enlongate as shown.
c l There can be no binding between screw
head and trigger.
Scale: 1:1
TRIGGER SEAR— SELECT FIRE I
14
SELECT FIRE 10/22
.187 radius.
(using 3/8 end mill, machine flush with surface "A"
.093 dia— thru
(Drawing may be used
as a template except
for hole location)
.093 dia— thru
(CAUTION— lay out hole location on both
sides and drill, using a smaller drill, from both
sides, then finish drill to .093 dia.)
.170
170
SELECT FIRE II LEVER
.475
H-.125
.093 drill rod.
Silver solder to lever.
J i
.047*
.062
* The .047 (max) deep flat on shaft
is cut by hand with select lever in
place assembled to trigger and held
in semi-auto position. Do not cut
beyond 1/2 the diameter of the shaft.
Final fitting can be accomplished by
reducing the height of the "A" surface
of the trigger sear. In final fitting, the
lever should move forward with no
binding and cam trigger sear down
against sear spring pressure.
TRIGGER SEAR MODIFICATION
Scale: 1:1
120
h-.075
End view
TRIGGER, TRIGGER SEAR & SELECT FIRE II LEVER
15
Full Auto Operation— Rear Mounted Arrestor
With a loaded magazine inserted, a round
chambered, Select Fire II lever "1" forward and
safety off, you are ready to fire full auto. The
trigger is pulled (slight upward pressure is
required on Select Fire I), the hammer drops
and the gun fires.
The bolt starts the recoil cycle camming the
hammer rearward which, with the bolt arrestor
spring i4 4" attached, begins to exert lifting
pressure against the arrestor actuating pin "6"
attached to the bolt arrestor "7'\ This spring
lifting pressure is increased progressively as the
hammer is cammed rearward. However, the
bolt arrestor "7" is limited in its upward
movement due to its contact with the bottom of
the bolt. Just short of full recoil the auto-sear
"3" is rotated rearward under spring pressure
and is in position to catch the hammer on its
auto-sear notch as the hammer starts to follow
the bolt back in counter-recoil
In counter-recoil the bolt strips another round
from the magazine and chambers it. When the
bolt is within .0 1 5 to .0 1 8 of battery position the
bolt arrestor "T will rise behind it. The bolt will
make contact with the breech face of the barrel
and start to bounce rearward, much like a
hammer striking an anvil. However, its bounce
is limited to the .015 to .018 clearance between
the lug on the arrestor and the back of the bolt
which is measured when the bolt is fully closed.
While this was taking place another sequence
was happening. When the bolt was .010 to .015
from battery position, the auto-sear trip pin "5"
mounted to the bolt tripped the auto-sear off its
sear notch on the hammer. Although these two
sequences take place almost simultaneously,
the bolt is allowed enough time to strike the
breech face, bounce back against the arrestor
lug and return to battery as the hammer is
falling. Thus the hammer is allowed full access
to the firing pin.
The hammer, in its fall, will describe an arc of
about 60 degrees. When the hammer reaches
about the last 20 degrees of this arc, the bolt
arrestor actuator spring "4" will start to exert
downward pressure on the arrestor pin "6"
This spring pressure increases during the last
few degrees of the hammer's movement, thereby
lowering the arrestor away from the bolt in
order to allow the bolt, in counter-recoiK to
move back over it. (In the front mounted
arrestor configuration, the bolt arrestor is
17
SELECT FIRE 10/22
18
SELECT FIRE 10/22
19
SELECT FIRE 10/22
20
SELECT FIRE 10/22
cammed down by the arrestor cam-down pin
"12".) The gun fires again and another cycle
starts.
In semi-auto all of the foregoing takes place
except when the auto-sear is tripped, the hammer
falls only down to the trigger sear which catches
it and awaits the trigger being released and
again squeezed. All full automatic operations
within the gun take place before semi-auto .
You can readily see that Ruger's original
design has not been changed, only added to. All
of the reliability is left in the gun.
21
SELECT FIRE 10/22
22
Fitting Rear Arrestor To Bolt Clearance
Assemble the bolt in the receiver without the
cocking handle and recoil spring. Place the
arrestor on its pivot pin in the trigger housing
and place the trigger housing in the action using
the 2 receiver cross pins.
Push the bolt forward to the battery position.
If the arrestor lug falls behind the bolt, measure
the clearance between the bolt face and the
barrel face. If the arrestor does not fall behind
the bolt, check to see that it lies flat against the
side of the trigger housing. Using a small rod or
screwdriver, attempt to push it into position
behind the bolt — gently! If it doesn't go behind
the bolt, disassemble and take a ,0 10 to .0 1 5 cut
off the arrestor lug and try again. Once the
This drawing may be used as a rough template to
make the hammer bushing clearance cut. Be careful
not to over-cut The arrestor must stay in place
behind the hammer bushing as It moves up and
down. It must be cut deep enough to allow the top of
the arrestor lug to retract enough to be level with the
top of the trigger housing.
arrestor lug locks the bolt, you will know where
you are since you can measure the bolt face
clearance with feeler gauges. Attempt to get a
nominal clearance of .020.
23
SELECT FIRE 10/22
NOT TO
.020 brass
hammer
bushing
spacer
Bolt arrestor
actuator spring
except for spring contour
and cam-down pin
REAR MOUNTED ARRESTOR
PARTS VIEW
24
SELECT FIRE 10/22
8-40 thread
Scale: 4:1
i
.160
1
,215
,094
REAR ARRESTOR PIVOT PIN
(Needed only if you are using the rear mounting arrestor)
The rear arrestor pivot pin is best made from
#20 drill rod. However, it can be made from an
6-40 screw. There must be an unthreaded
portion (.093) after the head is removed. This
portion protrudes through the trigger housing
for the arrestor to pivot on. These 8-40 gun
screws will vary In hardness so the first step is
to anneal. The diameter of these screws will
vary from .161 to .162 dia. Since the pivot pin
hole drilled in the arrestor will be .161 dia, you
may have to machine a small amount off the
screw to allow for a perfect fit. The arrestor
should pivot freely and yet have no slop. Fit the
pin to the arrestor, not the other way around. A
slot cut In the threaded end will assist tightening
It In the trigger housing.
When complete, the screw can be rehardened
and drawn to a dark blue color, 900 degrees F if
you have an oven.
In the final assembly the pivot pin must be
epoxied in the threaded hole of the housing.
We suggest using either an aluminum or steel
epoxy.
25
SELECT FIRE 10/22
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SELECT FIRE 10/22
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SELECT FIRE 10/22
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ADJUSTING THE REAR MOUNTED ARRESTOR ACTUATOR SPRING
Adjust the spring to approximately 40 degrees
from hammer surface, as shown. Assemble the
hammer to the trigger housing without hammer
spring and strut. With the hammer in the
upright position place arrestor on pin. Move
hammer back to cocked position and lower
arrestor to spring. Slip spring loop over arrestor
actuator pin and lower hammer and arrestor
until ejector pin can be inserted over top of
arrestor arm. The ejector pin limits upward
travel of the arrestor. The spring angle in
relation to the hammer should be adjusted so
that It will start to apply downward spring
pressure when the hammer is 20 degrees from
vertical.
28
SELECT FIRE 10/22
— 13/16 —
^
r
CZEH
.080 OFFSET
EJECTOR PIN HOLE
; Grind this radius back 1/16 to allow full retraction of
.030 magazine latch plunger, since overall length has
been shortened due to bending.
NOT TO SCALE
ALTERATION OF EJECTOR
(Rear Mounted Arrestor Only)
Ejector must be annealed before bending. After
completion, reharden and draw to 500 degrees F for
1 hour.
29
SELECT FIRE 10/22
30
SELECT FIRE 10/22
31
SELECT FIRE 10/22
Fitting Front Mounted Arrestor To Bolt Clearance
The same basic procedure is followed as with
the rear arrestor except a 3/ 16 diameter slave
pin, .950 long, is used to assemble the arrestor
and then replaced by pushing through the
regular front receiver cross pin after the rear
receiver cross pin has been installed. If the
If the magazine latch plunger does not fully
retract grind thla surface back to clear
original bolt lock clearance cut In magazine
1/8 drill thru
ARRESTOR RELEASE LEVER (Optional)
Make From 5/64 x 1/2 Flat Ground Stock.
This drawing may be used for template. Distance
"A" is critical and must be carefully fitted to arrestor
cut. The proper fit is a slight looseness when the
arrestor Is in the up position. There must be no
binding. After fitting, polish both the arrestor cut
and the lever end. The lever fits into the original bolt
lock slot and the visible end is shaped to match the
bolt hold open lever that must be discarded. It may
be necessary to clean the slot slightly with a flat
needle file. After final fitting, harden.
^1
Use this drawing as a rough template to shape cam
surface. Final fitting of cam surface should be done
by hand, so leave some extra metal.
Shown here is a small pin that has been added to the
hammer. This pin trips the bolt arrestor as the
hammer travels forward to strike the firing pin.
arrestor lug falls and locks the bolt when it is
pushed into battery, measure the clearance
between the bolt face and barrel face. The final
clearance should be between .015 and .018. If
the clearance is short, disassemble and place the
bolt back into the milling machine and re-cut to
bring the clearance to tolerance.
33
SELECT FIRE 10/22
for magazine lever notch
latch plunger (optional)
BOLT ARRESTOR
.062 HAMMER
BUSHING SPACER
STANDARD RIGHT
HAMMER BUSHING
NOT TO SCALE
Arrestor
cam -down
pin
ALTERED LEFT
HAMMER BUSHING
Arrestor
lifting
spring
FRONT MOUNTED ARRESTOR
PARTS VIEW
34
SELECT FIRE 10/22
Scale: 2:1
FRONT MOUNTED ARRESTOR
Make from 3/32 x 1/2 inch flat ground stock.
To fit cam surface "A" to arrestor cam-down
pin attached to hammer, proceed as follows:
Assemble Into trigger housing using the front
receiver cross pin. Insert the ejector pin through
the trigger housing and arrestor. The ejector
pin limits the arrestor movement. In the up
position the arrestor lug should protrude .090
to .100 above the trigger housing.
Holding the arrestor in the up position, move
the hammer forward. The cam-down pin should
make first contact with arrestor cam surface
when the hammer is 17 to 20 degrees from
vertical. The cam surface curve from first
contact with the pin to the fully cammed down
position (hammer vertical) should describe a
slight parabolic curve. The arrestor lug should
be level with the top of the trigger housing
when the hammer is vertical. Caution: At this
time make sure that the bottom of the arrestor
is not bottomed out against the hammer
bushing or the ejector pin. There must be
enough clearance to allow the hammer to
move about 2 degrees past vertical. This will
assure clearance between the cam-down pin
and cam surface movement downward. Other-
wise, the pin will bend or break. With the bolt
assembled in the gun, the hammer is limited in
its forward movement to the vertical position
by the back of the bolt. The ejector pin
clearance hole in the arrestor may be enlarged
slightly if more up or down movement is
required to meet specifications.
Polish arrestor cam surface before heat
treating. If you are using 0-1 oil hardening
steel, draw arrestor for 2 hours at 900 to 925
degrees F after hardening. If you do not have
equipment for this heat treating then make
your arrestor from mild steel (flat ground
stock) and case harden. Kasenit works well.
Follow the directions on the can and give it 2
treatments. The arrestor takes a lot of stress at
1200 rounds per minutel The auto-sear can,
also, be made from mild steel and case
hardened. Mild steel flat ground stock can be
had in both 3/16 x 1/2 and 3/32 x 1/2. It cannot
be had in 5/64 thickness which is needed to
fabricate the arrestor release lever.
35
SELECT FIRE 10/22
36
SELECT FIRE 10/22
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37
SELECT FIRE 10/22
38
SELECT FIRE 10/22
39
SELECT FIRE 10/22
Altered parts for front mounted arrestor. As stated in text, there are
advantages to both front and rear mounted arrestors, with the final
choice being determined mainly by the machining facilities and expertise
available to the person doing the conversion.
prototype differs slightly from the drawing and has
extra lightening holes added.
40
ADDENDUM
(The following was an instruction sheet supplied
by the TEK plant when they were producing these
converted Ruger 10/22's.)
The bolt lock and spring have been removed
from your gun to make room for the conversion
parts, otherwise the gun utilizes all the remaining
parts and operates just as it came from the Ruger
factory in the semiauto mode. In the full-auto
mode it still operates as it came from the Ruger
factory except the sear is operated automatically
by the cycling bolt as long as the trigger is held
back, Twenty-two ammo is greasy, waxy and has
a tendency to leave a lot of fouling behind in the
action. It is not, however, necessary to completely
disassemble the gun for normal cleaning. It is
prudent to clean the action after about 500 rounds
by retracting the bolt and placing a wooden dowel
of about 3/16-inch diameter by l :, /«-inch long
between the bolt face and the breech end of the
barrel to hold the bolt open since the bolt lock is no
longer in the gun.
With an old toothbrush or something similar
dipped in Hoppes, WD-40, etc., scrub the bolt face
and parts of the action that you can reach. Pay
particular attention to the recessed bolt face and
extractor slot in the barrel. Dry with a lint free rag
or cleaning patch. Q-tip sticks are handy for
cleaning. Spray very lightly or wipe down with
Break Free, WD-40, etc. Clean the barrel in the
normal fashion but, leave a dry chamber as you
should with any rifle. With such cleaning, your
gun should function properly for thousands of
rounds.
If and when you must break the gun down
completely, follow the procedure described here to
prevent possible damage to the parts. The bolt
arrestor lifting spring which is attached to the
hammer MUST lay on the right side of the long
arm of the auto-sear spring. Looking down on the
trigger housing, the parts and spring should be as
follows, from left to right: Bolt arrestor, ejector,
long arm of auto-sear spring set behind the ejector
pin, bolt arrestor lifting spring. When all parts
have been cleaned and reassembled in the trigger
housing, using the 3/16-inch diameter slave pin
supplied, lay the barrel and action on the bench,
barrel pointing to your left, action upside down.
Using the bolt handle, retract the bolt about
1/2-inch and place an empty .22 case between the
bolt and barrel face to hold the bolt partially open.
Place trigger housing into the receiver and insert
the rear receiver cross pin. Insert the front cross
pin, pushing out and replacing the slave pin. Both
cross pins are push fits— DO NOT FORCE.
CAUTION— the front cross pin must be inserted
going away from you, or, in other words, from the
bolt handle side (closest to you), through to the
serial number side. The reverse of this procedure
can damage the bolt arrestor which is fitted to
close tolerances.
Wear shooting glasses and keep other people
clear of the right side of the gun when shooting.
Empty, hot cases really flow from the 10/22 in
full-auto. Extractors have, also, been known to
blow off 10/22's. Have fun but be careful, the
firepower of this gun is awesome.
You can remove all TEK parts, replace the bolt
lock and spring, and your gun works just like the
original.
The original bolt lock has been replaced with a
look-alike lever that retracts the bolt arrestor. Pull
back on the lever to retract the arrestor to open the
bolt when the hammer is cocked. This allows you
to unload the gun if there is a round in the
chamber.
To adjust the rate of fire, use the Allen wrench
supplied and tighten until the bolt will just stay
open when retracted by the bolt handle. This is the
ideal slow fire setting, although you can adjust it
slower. To insure better reliability, test fire under
extreme weather (hot and cold) conditions.
CAUTION: The bolt cannot be opened if the
hammer is down and the safety is on. You must
place the safety on fire position to open the bolt
when the hammer is in the fired position.
41
