223 Palma Rifle Cartridges
There seems to be some interest in allowing the 223 cartridge to be
officially used in Palma Completion. So how does the 223 cartridge
compare to the standard NATO 7.62 cartridge using the 155 Sierra Palma
Bullets? The 155 Sierra Bullets had been selected as the latest official
standard bullet to level the field of shooters. The 155 is not the
best or the worst bullet in the 7.62 NATO line up for long range shooting.
However, this bullet is one that will separate the men from the boys in terms
of wind shooting at 1000 yards. So if the 233 cartridge is added to
the Palma Listing, which bullet will be allowed for it? Let’s assume
that any bullet may be used with the 223 cartridge and compare the Sierra
80 grain MatchKing HPBT bullet to the Sierra 155 Palma bullet at some typical
muzzle velocities for Palma Rifles. There are many ways one could compare
the two cartridges. So let’s start by looking at the two bullets ballistic
coefficients, then compare impulse recoil of the two cartridges, and last
review the results of simulated 100 random shot 1000 yard target with slightly
varying environmental conditions for both cartridges at their typical muzzle
The ballistic coefficients for the two bullets are fairly close with
a slight advantage going to the 30 Caliber 155 Sierra Palma bullets.
155 grain Palma Bullet
0.450 Above 2600 fps
0.443 From 2200 to 1800 fps
0.417 Below 1800 fps
Typical Muzzle Velocity for Palma Rifle = 2950 fps
Velocity at 1000 Yard Target = 1315 fps
Change in velocity = 1535 fps
Flight Time to 1000 Yard Target = 1.5419 seconds
Proportional Ballistic Coefficient for 1000 Yards = .437
80 grain MatchKing HPBT
0.420 Above 2200 fps
0.400 From 2200 to 1800 fps
0.393 Below 1800 fps
Typical Muzzle Velocity for Palma Rifle = 3040 fps
Velocity at 1000 Yard Target = 1284 fps
Change in velocity = 1756 fps
Flight Time to 1000 Yard Target = 1.5407 seconds
Proportional Ballistic Coefficient for 1000 Yards = 0.408
The proportional ballistic coefficient at 1000 yards is 0.437 for
the 155 grain Palma Bullet and 0.408 for the 80 grain MatchKing.
Flight times are very close with the 80 winning by a photo finish of 0.0012
seconds. If the 80 grain MatchKing started at 3000 fps the two would
be tied at 1000 yards. At 800 and 900 yards the 80 grain MatchKing
would be slightly ahead of the 155 grain Palma Bullet if started at 3000
fps. No great conclusions here. Both bullets are well above
the speed of sound. However, since the 155 Palma bullets has less
velocity lost going the 1000 yards it should be slightly better at handling
minor wind changes.
The Recoil Impulse for the two cartridges is quite different.
For the smaller 80 grain MatchKing the Recoil Impulse is 1.53 lb-sec while
the 155 grain Palma bullet has a Recoil Impulse of 2.87 lb-sec.
The impulse recoil is calculated has follows:
Impulse Recoil = Bullet Weight in grains times muzzle velocity in
fps times the powder charge in grains times 4000 and all divided by 225400.
Bottom line is the Palma Rifle using the 223 Cartridge will have about
half the impulse recoil than one that uses 7.62 NATO Cartridge. How
much of a factor is this going to be? All one can do on this issue
is to speculate, theorize, and voice opinions. So let’s just think
about what differences the feeble 223 cartridge has made on across the course
shooting in High Power Rifle National Match Shooting. The switch to
the 233 cartridge has for the most part improved shooters scores. Mainly
all the improvements I have heard shooters rave about have been in the
two rapid fire stages and 200 yard standing. The talk on 600 yard
slow fire stage has been more of wind conditions indicating that the longer
sight radius and better bullet ballistics used for the M1A’s had an advantage.
However the basic rule to winning still favored the sleazy 223 cartridge,
i.e. the match is won at 200 and only to be lost at 600. So any talk
about the benefits or lack there of for the frail 223 cartridge at the longer
600 range seem to have been over shadowed by the benefits at 200 and 300
yards. However, having half the impulse recoil and longer sight radius
on the Palma Rifle the puny little 223 cartridge using 80 or 90 grain bullet
maybe just the ticket. It would be much less punishing then the 308,
especially for anyone with back problems. So only time will tell.
100 shot simulated 1000 yard targets for the two bullets. The
settings for muzzle velocity and environmental variables used for the
target simulation were as following:
Muzzle Velocity: 2950 fps for the 155 gr. and 3040 fps for the 80
Muzzle Velocity Standard Deviation: 9 fps for both
Horizontal Wind Velocity: 15 mph
Horizontal Wind Variation: ±3 mph
Horizontal Wind Direction: 45 degrees
Horizontal Wind Direction Variation: ±5 degrees
I added a little vertical wind component so the simulation would be
more like shooting at Camp Grayling, MI.
Vertical Wind Velocity: 1 mph
Vertical Wind Velocity Variation: ±0.5 mph
Target with 100 Shots for the 155 Sierra Palma Bullet
Target Score: 914 – 16X
Standard Deviation from Groups Center: 6.215 inches
Target with 100 Shots for the 80 Sierra MatchKing Bullet
Target Score: 889 – 12X
Standard Deviation from Groups Center: 6.533 inches
The 155 grain Palma Bullet shows a 2.5 point per 10 shots advantage
over the 80 grain MatchKing bullet along with a 0.318 inch less standard
deviation for group size from group center. So the 155 Palma is
a clean winner in this comparison. However, the question is will the lower
recoil for the 223 cartridge allow some shooters to have a more consistent
hold and enhanced follow through where by allowing them to shoot high
scores with the lighter bullets? I believe the answer will be YES
Targets were generated using my Silhouette Ballistics
Now all this interest in shooting the 223 at longer distances has
got my interest. For those that do not know me, all my competitive
shooting has been limited to the stand up game of Silhouette. I
have been playing around the last couple of years on Wednesday’s shooting
some 600 yards at Washtenaw Sportsman’s Club in Ypsilanti, MI. Now
all this has got me thinking about a 223 Palma rifle for shooting on 600
yards on Wednesday’s and 1000 yards after some of the Silhouette Matches.
The 223 Palma Rifle would be fun to shoot and no brass to go and find.
What would be a good match chamber for the 223 Palma Rifle using the
80 grain Sierra MatchKings?
I would like the pressure ring just above the boat tail to be right
at the shoulder to neck junction in the case. That would make the
loaded round about 2.500 inches long with a loaded case powder water capacity
of 27.1 grains. One should be able to use around 28 grains of powder
and push the 80 grain bullets in the 3000 fps plus range with copper crusher
pressure values in the 55,000 to 56,000 range. With the right powder
and etc. we will see them flying closer to the 3100 fps mark.
Leade Angle: 1.5°
Freebore or Throat Diameter: 0.225 tapered down to 0.224
Freebore or Throat Length: Whatever it takes for a COL of 2.500 inches
using the 80 grain MatchKings.
Any Questions or
Web Page Comments
July 8, 2003