Rifle Shooter – July 2019

barrel and S&L .22 LR sound moderator and Hawke Vantage
scope. Then again at 30 yards to measure velocity and thus
determine the true ballistic coefficient (BC) of the bullet in
flight. The 40gr subs worked out at a BC 0.088 and the 42gr
Max at 0.218 BC, a marked improvement already.
The ballistic media was set up at 30 yards and accuracy
tests were conducted at 30 and 50 yards. Ballistic trajectory
down range was run through the QuickTarget ballistic
program and Hawke BRC2, having computed the BC by
measuring the true velocity difference down range.
Instantly noticeable was the higher velocity of the 42gr
Max Win subs: 1,049 fps as compared to the 1,022 fps of
the standard 40gr version. You can actually feel the
difference on firing as there is a small but noticeable
difference in recoil and impact on the ballistic media made
the target shake for the 42gr loading.
In the Sako Finnfire, there was no perceivable difference in
accuracy, to be honest, at 30 or 50 yards. The 40gr subs
shot 0.365" five-shot groups at 30 yards and 0.525" groups
at 50 yards. The heavier 42gr Maxes shot almost identical
0.375" 30-yard groups and actually a tighter group at 50
yards with five shots grouping into 0.495".
Working out down-range performance (i.e. trajectory) is
quite hard as BCs given from manufacturers are either

non-existent or optimistic! Shoot a velocity at two differing

ranges and work it out yourself, then round it through a

ballistics program and then set out targets at differing

ranges to check. Atmospheric conditions will alter results.

Now you can see that the 42gr Max actually has a ballistic

advantage over the 40gr subsonics as the combination of

extra weight and momentum, higher velocity and better BC

value all equate to better ballistics down range.

At 50 yards, the 42gr Max still has 998 fps velocity

compared to the 40gr subs at 915 fps. That translates to 93

and 74 ft/lbs energy respectively. That’s quite a big

difference at a standard rabbit range. This also means that

at 100 yards the 42gr drops -6.6" compared to the -8.4" of

the 40gr subs. Wind drift, too, is less with the heavier 42gr

Max at only 0.7" at 50 yards whereas the 40gr bullet is

drifting 1.6". Definite miss on a head shot.

That’s all well and good: so we know they are accurate

enough, the 42gr Max has better down-range trajectory

performance. How about penetration and energy transfer?

Down range is where it all matters and is where the large

hollow cavity 40gr Winchesters have always been popular

with hunters. I had a total penetration of 8.0" into the

ballistic media and actually a very straight line, with no

deviations. The bullet frontal section (i.e. hollow point)

http://www.rifleshootermagazine.co.uk 39

AMMUNITION TEST WITH BROADSWORD

»

ABOVE LEFT: The

original Win 40gr is

an impressively

accurate subsonic

round at 30 yards

ABOVE: Win 40gr

subs at 50 yards

hovered around

the 0.5" mark.

BELOW LEFT: The

42gr Max subs

were very accurate

at 30 yards...

BELOW RIGHT: ...

while five-shot

groups at 50 yards

coming in under 0.5"

makes the 42gr Max

a real rabbit getter!