Captain Slug RIVALBURN3 User manual

RIVALBURN3 ASSEMBLY INSTRUCTIONS
The
Rivalburn 3
is a Mag
-
Fed Pump
-
Action Homemade Nerf Blaster design released as a CC
-
NC license file set by Captain
Slug (http://www.captainslug.com).
You are welcome to and encouraged to modify the files in any way you want. The Majority of the parts can be printed
with infill as low as 20% in PLA, but I would recommend printing in layers of 300 Micron or smaller. I would recommend
a minimum of 1.5mm walls/perimeters for every part.
Hardware kits and Full Blasters are available for sale as made-to-order items. I'm producing these myself in what
remains of my free time.
https://www.etsy.com/shop/CaptainSlug
DO NOT STORE IN TEMPERATURES ABOVE 100F. Storing the blaster inside of a car in warmer months will
cause the printed parts to distort or warp beyond their intended shape. If you have to store one in a vehicle,
store it in the trunk.
DO NOT use this blaster for indoor wars or wars involving very short distances. The muzzle velocities this
design can reach are between 150fps and 210fps depending upon the darts used and the spring installed. If
indoor use is intended, obtain the lower fps springs that are currently available for this design (K31 and 788)
and use them.

For most of the above hardware l
i
st the quantities are the MINIMUM required for assembly. Easily
-
lost items will have
several spares and I typically include extras of the majority of the items.
To assemble this blaster you will need a Slotted Screwdriver, Small Philips Screwdriver, Scissors, 3/8” Combination
Wrench, and maybe a Small Round Needle File.
The Plunger Tube in the Hardware Kit does come pre-lubricated. But it's also a good idea to have extra lubricant on-hand
for the Plunger Tube and I would recommend only using a clear Silicone Grease such as Oatey's brand #30219. Any clear
90% silicone grease will work fine so long as it does not include any additives. NEVER USE SILICONE LUBRICANT FROM
AN AEROSOL CAN. The propellants used in those are harmful to plastic parts.
ALSO AVOID DRY-FIRING THIS BLASTER EXCESSIVELY. Firing without a dart in the barrel will add unneeded wear on this
blaster, especially if the higher load rating springs are installed. Also do not pull the trigger with the foregrip in the
rearward position (with the breech open). The breech being slammed closed by the main spring is very likely to damage
both the breech itself and the magwell.

Above is a list of every printed part needed to assemble this blaster
.
The majority of the through holes should print to
the required tolerance, but you will likely have one or two that may require minimal filing. Also make sure to trim off any
burrs or oversized edges.
Insert a
hex
stan
doff in
to th
e socket
from the
back of the Frontbutt print. Use a
screwdriver to push it as far into the
socket as you can manage.
A. Drive a 4-40 screw into the hex standoff from the hole in the side of the print to draw it down to the bottom of
the socket. Look in through the perpendicular hole in the front of the print to confirm that the standoff is pulled
far enough to no longer be intersecting the hole.
B. Drive a 4-40 screw in through the perpendicular hole at the front of the print to retain the standoff
C. Remove the 4-40 screw driven into the hex standoff during Step A
D. Repeat the process for the opposite side

Duplicate the same
steps used on the Front
butt print to add
two
hex standoffs to the sockets in the
Co
upler
print.
Place a
10
-
32 hex nut onto the end of a 1
-
3/4” length
screw, then push the hex nut into the front of the spring guide of
BackButt until it bottoms out. Unscrew the long screw from the hex nut.
Insert the long screw in from the back of the Buttplate and the pin through the BackButt and screw it into the hex nut
until tight.
Set this assembly aside.
Remove the integrated
printed
support
from the backside interior of the Magback print and throw it away.
Duplicate the same
steps used on the Front
butt print to add
fou
r hex standoffs to the so
c
k
e
t
s
i
n
t
h
e
M
a
g
B
a
c
k
p
r
i
n
t
.

Line
up
the hole in the
Elevator
print with the holes in the MagBack
side
s
and
drive a 4
-
40 screw in from each side.
Tie a knot into one end of the 3/32” elastic and feed it through the hole in the front of the Elevator print, then in
through the hole in the middle of the Magback print.
Slide a hex nut into the slot in the back of the Magback print, then start to drive a 10-32 short screw into it through the
matching hole.
Pull up the slack in the elastic cord, then loop the elastic around the screw underneath the head of it, then tighten the
screw onto the cord. The cord should be pulling the Elevator so that it rests in the upright position.
Trim off the excess elastic cord using scissors.
If installation of t
he plung
er tube cover is desi
red
later on, feed a long 10
-
32 screw in through the front of the Magback
print, then drive it through a hex nut until the hex nut is pulled to the bottom of the socket in the back of the print.
Line the Gate print up with the front of the Magback print as shown.
Tie a knot in one end of the 3/32” elastic cord, then feed it through the front of the Gate print, and then through the
hole in the Magback print. Pull up the slack and then feed it through the perpendicular hole that goes under the rail
segment at the top of the print.
Pull up the slack again and feed it down through the upward hole on the other side of the print, and then through the
Gate print.
Pull of the slack and while holding the cord taught tie a knot as close to the Gate print as you can manage.
Trim off the excess with scissors and let the knot get pulled into the widened portion of the hole in the Gate print.

Hook an extension spring ont
o
the peg on the Sear print, and then use the Sear print to fish the spring do
wn into
the
Grip print. Connect the available opposite loop on the spring onto the hook inside the Grip print.
Insert the round standoff into the hole in the middle of the Sear, and then slide it into the Grip until it lines up with the
hole in the Grip print.
Secure the
round standoff with two 4
-
40 screws.
Slide the Trigger print up into the Grip print from the slot in the underside of the front of the Grip print until it is wedged
under the front lip of the Sear. Line up the holes in the Trigger and Grip prints, then force a short print through both.
Force the Tguard print into the square slot in the Grip print, then secure with two 4-40 screws.
Tie a knot at one
end of the 3/32
”
elastic cord and r
epea
t a similar process with the Magcap, Detent
, and Magfront
prints. The cord will not need to be pulled very tight before tying the knot on the opposite side.
Trim the excess with scissors. If you have trouble feeding the cord through, clean the hole with a drill bit or trim the end
of the cord to remove the frayed end.
Use four 4-40 screws driven through the front of the MagCap print to secure the assembly.

Sandw
ich the resulting assembly with the u
-
channel pair.
Move the elastic cord
at the front of the
assembly
out of the way
so that you ca
n slide the barrel into the front
.
Then slide the Foregrip print over the u-channel pair.
Slide the Muzzle print onto the u
-
channel pair, and over the barrel. Then secure it by driving a 4
-
40 screw into each side.
Use a knife
or pliers
to trim
or
pry off the
selective brims on the rail segments prints.
Wedge the rail prints inbetween the muzzle and Magfront assembly above the barrel. There should be three Rail prints
and one RailD print.

Push a he
x nut into the slot in the top of the Mag
f
ront
assembly
, then feed the
13
”
length
threaded rod
through the
muzzle, through all of the rail segment prints, and then into the front of the hex nut.
Drive the threaded rod into the hex nut, leaving roughly ½” of the threaded rod still exposed out the front of the muzzle.
Drive a hex nut onto the threaded rod and tighten.
Slide the insert print
s
into the slots
in
the top of the MagLower
L and MagLowerR
prints.
Secure the MagLower prints to the sides of the MagFront assembly using 4-40 screws.
Slide th
e MagBack into the u
-
channels and line it up with the holes in the MagLower prints.
Secure the Magback print using six 4-40 screws.

Slide the Prong print into the slot in the Foregrip print so that the hol
es in both are lined up.
Secure using two or four 4-40 screws.
Secure the bolt arms to the ra
mrod using two 4
-
40 screws. Add an o
-
ring to the undercut on the ramrod base.
Then peel of the backing from the shockpad and adhere it to the back of the ramrod base.
Slide the Bolt arms in through th
e Magback and slowly feed it
through and around all of the components until the holes
in the front end of the Bolt arms are lined up with the holes in the Foregrip.
Secure the
F
oregrip to the Bolt Arms
using four short 10
-
32 screws.

Force the plung
er tube over the ramrod base and into the back of the Magback print until it bottoms out. You may need
to use a hammer to lightly tap it until seated.
Add an o-ring to the undercut on the Plunger print, and then feed the plunger into the plunger tube.
Slide the grip assembly into the u
-
channel pair.
Slide the (
optional
) plunger cover over the plunger tube. And then the (optional) grip insert into the bottom of the grip.
S
lide the Coupler, Stock Spacer, and Frontbutt into the u
-
channel pair. Th
en secure with 4
-
40 screws.
Adda hex nut to the socket in the front of the Frontbutt print.

The following steps
are option
al.
Wedge a printed lower stock spacer or spacer tubing between the heel of the Grip assembly and the lower tang of the
Frontbutt print.
Insert a hex nut into the slot in the (optional) Grip insert if present.
Add a hex nut to one end of the 8.25” length threaded rod and feed it through the shown prints, then drive it into the
hex nut in the bottom of the Grip assembly.
Tighten the still exposed hex nut.
Add a main spring
of your choi
ce.
Feed a long 10-32 screw in through the back of the Backbutt assembly, then drive it into the hex nut that was added to
the socket in the front of the Frontbutt print until tightened.
Drive a
4
-
40 screw into the angled hole in the front of the Muzzle print. This will act as the hop
-
up tab for the fired HIR
s.
To reduce the lift in the flight path of the fire HIRs, tighten this screw. To increase the lift in the flight path, loosen it
instead.

Insert a magazine into the
front of the blaster
until the deten
t
latches
.
This can be done w
he
never desired regardless of
the breech being open or closed. To remove the magazine, pull up on both sides of the MagDetent and push the mag
from the exposed portion of it that is behind the foregrip. Or alternatively point the blaster toward the ground.
Slide the foregrip back to compress the mainspring until the plunger gets engaged on the Sear. At the end of the foregrip
stroke and during over-travel of the plunger, the Prong on the foregrip will tip over the elevator. The elevator will hinge
down and trip the detent on the rival magazine causing an HIR to be ejected above the elevator. When the foregrip is
slid forwards the elevator will push the HIR up and into the path of the ramrod, which will then force it into the barrel.
Replacing the Main Spring does not require full disassembly of the Blaster. You just need to reverse the last 2 steps in
these instructions in order to take the buttplate off.
The Blaster and Hardware Kits are shipped with K25 springs. The K25 is rated slightly lower than the K26, which is also
available. The alternate spring option is the 788 which have to be purchased separately or opted for as a replacement.
The 788 spring is recommended for indoor use, or for younger players.
The magazine can be
refilled from the open loading port in the bottom of the blaster without
the magazine
being
removed.
The hole at the top of the magwell towards the front allows an HIR to be manually loaded ahead of the elevator output
port. This can be done to selectively add one or two additional HIRs into the barrel in tandem behind the one that was
loaded by the elevator system. Or to allow for an HIR to be loaded into the barrel when the magazine is empty (or
absent).
If an HIR gets stuck in the barrel, prime the blaster and leave the breech open. You will need to ramrod the jammed HIR
back into the open breech using a 1/2” or 5/8” dowel. Turn the blaster upside-down, and then slide the Gate print
forward. Tip the blaster forward or backward until the now-freed HIR can fall out the Jam Door port.