Mark,

In the late 70's my "mentor" in handloading (and firearms in general) built a 7x57
with a 25 inch Hart barrel that pushed a 160gr Sierra SBT at a little over 3200fps.
This was verified with two different chronographs (chronos were kinda rare in those
days) and further verified by Les Bowman (the man credited with developing the
7mm Rem Mag). When my mentor cut the barrel down to 22 inches he lost almost all
of the "magical" velocity. Although velocity was still higher than expected with
the 22 inch barrel. He tried to duplicate this with other barrels but never could.

I have occasionally seen rifles shoot significantly higher than expected velocities since
then--but not often. Although 3000fps seems a little high in your cartridge/barrel
length it is certainly credible. I have wondered if the new powders will produce
better velocities in big volume cases with short barrels.

My point was effeciency in short barreled, lightweight rifles. Magnum volume
cartridges, compared to the 30.06, like the 300 Wthby burns a little more than 30%
more powder to gain a tad more than 10% in velocity. This ratio, of 2%-3% increase
in powder for a 1% gain in velocity gets worse with shorter barrels. The 30.06 AI
achieves something closer to 1.5% powder increase to 1% velocity gain--with a 22
inch barrel. I spend a lot of time backpack or horsepack hunting in the San Juans or
the Sangre De Cristos or the Uncompahgre Plateau. My requirements are a rifle that
is easier to thread through the "elk jungles" of downed spruce/fir or Gambels oak
thickets and be very lightweight. Plus there is the recoil thing. This why I am a fan of
the 270Win. The .06 AI is about all the cartridge I am tough enough to shoot in a
7lb or less rifle. I take it with me to Alaska (grizzly/brown bears seem to like to "show
off" in my presence). Although a few years ago I shot a healthy sized bull elk stern to
stem with my 270Win and 150gr Barnes X at 340 yards. It is probably plenty cartridge
enough to kill a big bear. But I built the .06 AI's for Alaska trips so I that's what I use.

Trajectory/ballistics tables: I couldn't agree with you more. Twenty years ago I had
the ballistic tables for a number calibers/bullet weights from several manuals
dang near memorized. You're right--virtually all of the big game cartridges we are using
today, when using a 200 yard zero, there isn't plus or minus 3 inches difference at 400
yards between all of 'em. The 7x57 was developed in the early 1890's, the 30'06 was
developed in the early 1900's. A hundred years of cartridge development has resulted
in very small improvements in trajectory.

Casey

Neither did Les Bowman until they shot through his own chronograph.

Since Les Bowman, who's writings I think very highly of, has passed on there may be no way to verify that. Even if his records are available they are wrong on this topic.



I had a chronograph that was wrong by 75 fps. It seems that the new screens as mounted on the new holder were not aiming right.



Now that special barrel has been cut?



I don't believe a word of this.

Savge 99,

The chronograph was a Custom Chronograph with paper screens (I don't believe sky
screen chronos were yet on the market--and paper screens were still more accurate
until the advent of the Oehler 35). According to Les Bowman, it had been checked
against other chronos and in turn agreed with our Custom Chronograph.

Skepticism is a good thing--just don't get your foot to far in it.

Casey

I have an Accuchron chronograph here that uses paper screens. I got it new in the late 1960's. It was quite consistant I agree but I never calibrated it. In fact I have the data right here for many cartridges fired thru the metalized paper screens.

On 9-25-1965 my Browning 7mm RM made 3145 fps with 68 grs of surplus 4831 and the Sierra 160 gr SBT. The head expansion was .0005" using 9 1/2 primers, Rem brass and the barrel length was 24 3/16". I considered this a over maximum load. Later the same rifle was shooting the 160 gr Norma spitzer with 65 grs of the same powder at 2943 fps. The head expansion was nominal.

I can go over a hundred with ease by pushing the metric button on the speedometer! It must be some mix up like that.