A MOUSE ON STEROIDS
General
The .223 Remington (.223R) cartridge is the most
widely used centre fire cartridge in the western world.
The .223R was born from the .222 Remington in
1958. The military needed 20% more powder capac-
ity over the .222 Remington so they designed the
5.56 x 45 cartridge or in civilian terms, the .223 Re-
mington. Are the 5.56 and the .223R cartridges the
same? The answer is yes and no. The official Sport-
ing Arms and Ammunition Manufacturers Institute
(SAAMI) position is that chambers for military rifles
have a different configuration than those for sporting
rifles and chamber configuration together with the full
metal jacket military bullet may account for the higher
pressures that result when 5.56 ammunition is fired in
a .223R chamber. SAAMI recommends that a firearm
be fired with the cartridge designed by the manufac-
turer.
The DCRA experimented with the use of .223R and
adopted it in the late 1980’s. DCRA shooters used
the military issued IVI 62 grain bullet with good per-
formance out to 600 metres. To give the 62 gr bullet
good stability, shooters adopted the 1 in 9 inch twist
barrels. This decision led to problems later on when
the heavier bullets were introduced. Once the DCRA
went to handloaded ammunition in 1996, the rules
were changed to allow .223R bullet weights up to 81
grains to compete alongside the .308W/155 gr bul-
lets. The preferred .223R rifle barrel twist gradually
changed to 1 in 8 inches to stabilize the 80 grain bul-
lets as the 1 in 9 inch twist did not give guaranteed
stability at low density altitudes (low temperature,
near sea level and high barometric pressure).
The .223R/80 gr competed well against
the .308W/155 gr out to 900 yards; however, it
proved difficult to achieve equal scores when shoot-
ing at 1000 yards. The DCRA, being a forward think-
ing national rifle association, was among the first in
the world to allow the 91 grain bullet weight in
the .223R calibre. This can be credited to Clint Dahl-
strom who did the initial study of the .223R/90 gr and
his recommendation to the DCRA to adopt the
new .223R maximum bullet weight of 91 gr. Today
the .223R/91 gr weight limit is allowed by most of the
major national rifle associations around the world.
The little mouse gun is now on steroids using the 90
grain bullet and can compete with its .308W/155 big
rodent brother at all ranges out to 1000 yards. It
sounds like it should be simple to get the .223R to
shoot as well as the .308W/155 gr, but it is not
Loading
Achieving the best results when using the .223R/90 gr
starts with loading techniques for the 90 gr. It is not my
intention to give a thorough reloading lesson here but
only to establish a few important bench marks for re-
loading the .223R/90 gr. The .223R cartridge uses
slightly more than half the powder that is used in
the .308W. A nominal error in reloading a .308W is
almost twice as large in the .223R, making it difficult to
achieve the low extreme spreads in velocity (ES) and
standard deviation (SD) usually necessary for suc-
cessful long range shooting. To use the .223R/90 gr in
competition, I suggest the following considerations for
successful reloading.
Brass
Use Lapua brass for all .223R/90 gr reloading as
Lapua produces the highest quality and most uniform
brass. Lapua brass was initially issued with the nomi-
nal 103 gr case (not recommended). Later, Lapua is-
sued the nominal 95 gr case that has the word “Match”
on the 100 round plastic boxes and finally, the
95 gr
case arrived with the word “Match’ engraved on each
case head (recommended). After testing 1000 cases
of the latest engraved match brass, it was found to
have a small weight spread of 1.2 gr. Initially, I weigh
and sort brass to a 1/10 gr spread. After the 3
rd
and 6
th
firing, I re-weigh the brass and re-sort to the 1/10
th
gr
spread. After the ninth firing, I recycle the brass by
donating them to my favourite junior shooting pro-
gram as a fund raiser and purchase
new Lapua Match
brass. Brass should be trimmed to 1.55 inches each
time you full length resize and the case mouth should
be chamfered inside and out. Powder, primer and
bullet selection are discussed in later paragraphs.
For 1000 yard success you must achieve very
straight ammo with a low bullet run out of .001 inch or
less. I use the Redding .223R body die to resize the
case body and shoulder set back. I set back the
shoulder about ½ to ¾ thousandths from a fired case
measurement. The RCBS Precision Mic is a handy
tool for measuring head space and set back measure-
ments. I then use the Lee Collet neck sizing die to
resize the neck and to de-prime the case. It gives
36
a .0015 inch average neck tension with a loaded round
plus the am munition has the desired small run out
of .001 inch or less. If you use a full length neck bush-
ing Redding S die you also resize the base of the case
with a similar result. This low bullet run out is absolute-
ly necessary at 1000 yards as excessive run out en-
larges the group size. With every firing, I full length re-
size, re-trim, clean out the primer pockets and chamfer
the neck inside
and out. An hour in a brass clean-
ing vibrator makes your brass look new again.
Powders
The .223R is relatively easy to reload; however, we
are just concerned with the 90 gr bullet. I have focused
extensively on the Varget and Viht N150 powders. I
have found Varget gives an SD of 8 consistently while
the Viht N150 gives an SD of 5. Long range shooting
demands low SD‘s so Viht N150 is my choice of pow-
der. I think the slightly slower burning Viht N150 pow-
der translates to better SD’s.
I weigh powder to as close to 1 /100
th
of a grain as
possible to ensure low ES and SD. The Viht N150 has
the best temperature insensitivity of the Viht powders
and is comparable to Varget. Other powders that are
potentially suitable are: H4895, IMR 4007SSC, Viht
140, Viht N540, Viht N550, and Alliant Reloader 15.
Primers
There are many small rifle primers on the market
that work well with the .223R. However the
223R/90 gr load seems to demand a choice of only
a few primers for low ES and SD success. The CCI
450 magnum primers seem to work best. The PMC
SR Magnum, WSR or Federal 205M primers are
my next choice. My experience with the CCI BR4
indicates SD and ES are higher.
Bullets
There are four 90 gr bullets that are normally used
with the .223R namely Sierra, JLK and the Berger
90 gr VLD and the 90 gr BT. I use the Berger 90 gr
VLD exclusively. It is recommended to try both Ber-
gers to see which shoots the tightest groups for
you. The Berger VLD’s are normally seated 15
thousandths into the rifling and the Berger 90 BT
are normally seated with 20 thousandths jump.
With the long slender 90 gr bullet it is a natural
choice to give them a pointy mouse nose. I use the
Whidden pointing system to reduce the 0.050”
meplat to about 0.025” or ½ the production meplat
opening. If you are not pointing bullets for 1000
yard shooting you are missing out. The pointed
missiles reduce vertical stringing. Pointing im-
proves the Ballistic Coefficient numbers by
about 5%. The Berger 90 VLD has a G7 BC of
0.281 improving to 0.295 with pointing. It is re-
ported that pointing should improve the velocity
at the target by about 80 fps while the wind drift
is lessened by about 7 inches with the classic
90 degree wind at 10 MPH.
Barrels
To make the 90 gr bullet work, it is highly recom-
mended to use a 30 inch barrel with 6 ½ or 7 inch
twist. This is necessary to maintain bullet stability out
to 1000 yds. At the moment my 1 in 7 inch twist bar-
rel seems to work marginally better than my 6 ½ inch
twist barrel. Since barrel life seems to be about the
same as .308W/155 gr target barrels I will use a
competitive barrel life of 3000 rounds for
the .223R/90 gr. My older 223R/90 gr barrel has
2400 rounds fired through it and is still shooting tight
groups.
A “Mouse Hole” For the 90 gr
Talking about the “mouse hole” does not refer to the
chamber, but rather, to the section ahead of it (the
“throat”) and, in particular, the length of the parallel
non rifled section referred to as the “free bore”. A
measurement often missed in selection of the perfect
reamer is the distance between the drive band/boat-
tail junction of the bullet and the neck/shoulder junc-
tion of the case. Most of the newer bullets used in
target shooting today have very narrow drive bands
in order to increase the length and taper of the bullet
and thereby increase the BC. It is recommended to
seat the 90 gr bullet so that the drive band/boat tail
junction is about 0.020 inch ahead of the case neck/
shoulder junction. It must be appreciated that a
new .223R chamber may be slightly less than 0.020
inch while a 3000 round throat will exceed the 0.020”.
It is a must to have the narrow drive band centered in
the case neck. Building a custom rifle demands a
custom reamer designed for the bullet to be used.
For my mouse guns, I had a 223R/90 gr reamer de-
signed and made by Dave Kiff at Pacific Tool &
Gauge (PT&G) with a .164” free bore. For compari-
son, a .120” free bore reamer works for the 80 gr bul-
let family while the 62 gr IVI bullet works with a .069”
Wylde designed reamer. Free bore length has a ma-
jor effect on which weight bullet you can load, how
well the rifle shoots, as well as peak chamber pres-
sures and muzzle velocity (MV).
37
A PT&G reamer drawing (#31330 dated 5/6/10) designed
for the author was used in testing for this article. Using
the Berger 90 gr VLD at .0015 inch seating into the rifling
and the Berger 90 gr BT with .0020 inch jump ensures
the narrow drive band is inside the .223R case necks
with the .164” free bore reamer.
Putting it All Together
Steroids For The Mouse
Using the ballistic information from Bryan Litz’s
Applied
Ballistics for Long Range Shooting (2
nd
ed.)
, a compari-
son can be made between the .223R/90 gr Bergers and
the .308W Bergers. The Berger 90 gr VLD has a BC G7
of 0.281 while the Berger 90 gr BT is 0.262. For compari-
son, the Berger 155.5 gr Fullbore has a BC G7 of 0.237.
Berger 185 gr BT (popular with the F-Class FTR shoot-
ers) has a BC G7 of 0.283 while the Berger 220 gr BT
has a BC G7 of 0.323. Using these figures it becomes
apparent that the Berger 223R/90 gr should be a better
ballistic performer at 1000 yards than the 308W/155 gr,
and that it is equal to the Berger 185 gr but not as good
as the Berger 220 gr.
The magic muzzle velocity required to arrive at the sweet
spot for the Berger 90 gr VLD is 2850ft/sec while the
Berger 90 gr BT is sweetest at 2825ft/sec. A note of
caution concerning powder weight: use ½ gr less powder
with the Berger 90 gr BT compared to the Berger 90 gr
VLD. The pressure is higher using the Berger BT’s for
some reason that is not readily apparent. Some think it
may be due to different jacket material. The reduction of
the ½ gr and loss of 25ft/sec ensures that the loads are
safe using the 90 gr BT.
Steroid Recipe for My Mouse
My favourite load for the 1 in 7 inch twist barrel is 24.5 gr
of Viht N150 and the 6 ½ inch twist barrel is 25.1 gr of
Viht N150 in the Lapua Match cases (95.0 gr), CCI 450
magnum primers, and Berger 90 gr VLD’s seated 0.015
inches into the rifling with +/- 0.020” between the neck/
shoulder of the brass case and the boattail/ drive band
junction of the bullet. My OAL is 2.664” using the PT&G
reamer #31330. Muzzle velocity for both rifles is 2850ft/
sec with average extreme spread of 15 ft/sec and stand-
ard deviation of 5. Groups with the .223/90 from 100
yards to 1000 yards are usually tighter at every distance
than those with the .308/155.
Mouse Gun Description
All of the author’s shooting is Target Rifle as opposed to
F-Class. My first rifle is a Paramount .223R, with a Krieg-
er cut rifled barrel with 1 in 7 inch twist, while
the second rifle is a RPA .223R Quadlite, with a Brux
cut rifled barrel with 1 in 6 ½ inch twist. Both barrels
are 30 inch length, 4 grooves with #15 medium Pal-
ma profile. Both rifles have Gemini TR 701 prone
stocks. Front sights have RnR (Riles) 30 mm tubes
with .5 eagle eyes and Contra adjustable apertures
with 3.8 to 5.8 mm opening. Warner Euro #2 rear
sights are used to guide the 90 gr bullet in the wind
over the 1000 yard distance.
Comparison of 223R/90 gr with 308W/155 gr
Advantages of the 223R/90
x
30% less recoil and torque
x
About half the cost to reload
x
Better 300-1000 yard performance
x
Well made Berger bullets in the 90 gr family
x
Good for diagnosing trigger release and
follow through
x
Allows carrying close to 360 ammo rounds
within the airline baggage ammunition limit
of 5 kg (more than the 200 allowed with the
308W/155 gr.)
x
Excellent platform for new shooters
x
Allowed in TR in Canada and Match Rifle/
Palma in the USA
Disadvantages of the 223R/90
x
Requires more accurate hand loading to
keep muzzle velocity sp
read below 20ft/sec
and SD below 10
x
Can be difficult for target markers to find
smaller holes with the small chance of a hit
not being found on a poor target face
x
Smaller bullet selection in the market place
at the moment (only 2 Bergers currently rec-
ommended by the author)
x
Cases loaded close to maximum capacity
requiring careful load development
x
Barrel life still not finalized
38
I have shot both of my .223R rifles extensively us-
ing the ICFRA and the US NRA targets which both
have a smaller bulls-eye dimension than the DCRA
TR Target. All of the courses of fire are 15 rounds
which are normal in British Columbia and required
for US Palma shooting. Since most Canadian
shooters outside of British Columbia shoot the
DCRA target I have adjusted the scores according
to the DCRA target dimension standard so TR
readers can compare performance with their .308W
target rifles. Since the V-bull/X- ring vary in size I
have not listed the V/X-ring count. The scores listed
here have been recently shot in the period from
February to July 2012. The scores achieved are in
actual practice and match conditions using ICFRA
TR rules. The scores are:
300y/m – 75, 75, 75, 74, 75, 75, 75, 74, 74, 75, 75,
400m – 75, 75,
500y/m – 75, 75, 75, 75, 75, 75, 75, 75, 75,
600m/y – 75,75,75,75,75,75, 75,75,74,74,75,75,
72, 75, 75, 75, 74, 74, 75, 75, 72,
800y – 75, 74, 75, 75, 75,
900y – 75, 72, 75, 72, 75,
1000y – 74, 75, 72, 72, 71, 69, 74, 75, 75, 73, 72,
Final Thoughts
In my .223R progression over the years from 62 gr
to 90 gr bullets I have had some disappointing peri-
ods. Most of it was caused by having the wrong
twist barrel or the wrong reamer. Once I solved
those riddles, the performance of the .223R/90 gr
has been most reassuring having fired a total of just
over 21000 rounds of .223R since 1992. If the deci-
sion is made to try the .223R/90 gr, any rifle action
will suffice, but it must have the 1 in 7 or 6 ½ inch
twist barrel and the .164” free bore reamer. Any
compromise in barrel twist or free bore length may
result in poor performance. There are quite a
few .223R rifles around with the 1 in 9 inch twist
barrels on them from the IVI 62 gr cartridge days.
Installing a new 7 or 6 ½ inch twist barrel and using
the .164” free bore reamer will get that rifle back on
the range. If you still don’t want to use it, then do-
nate it to a new shooter to help them in their devel-
opment. The .223R/90 gr should reward any shoot-
er with success. With the advent of the 90 gr bullet,
the .223R mouse gun has become “Mighty Mouse”
Final Warning
These components and loads performed safely
in the author’s rifle and cannot be guaranteed
for other hand loaders and rifles.
Good hand
loading practices should be used at all times.
The listed loads may only be used with cham-
bers having considerable free bore to accept
the 90 gr at around 2.665” OAL. If the 90 gr bul-
lets are used in the shorter throated barrels, the
load must be reduced. Do not use the 90 VLD
powder weight suggested in this article for the
Berger 90 BT. Reduce the powder by at least ½
grain because of higher pressures.
Acknowledgements
No author is an island. Greg and Susan Bowman
provided invaluable advice and counsel (every bit
of which I took) in helping to develop this article.
Greg and Susan, while living in Oregon, are long
time friends of many Canadian shooters and are
frequent users of the .223R. Greg won the 2007
British Columbia Lieutenant Governor’s Prize using
the .223R.
Secondly, one cannot forget the in-depth testing
and development of the 90 gr .223R done by Clint
Dahlstrom. Clint published his investigative findings
“The New Challenge – 90’s in a .223” in the 2008
Winter/Spring Canadian Marksman. His conclu-
sions led Clint to recommend to the DCRA that
the .233R bullet weight limit be increased to 91
grains. His recommendations gave the author the
opportunity to benefit from the exploratory gamble
initiated with the 90 gr .223R
By Robert Pitcairn
