The Benjamin-Sheridan 397PA
By Ian Pellant
OK, this is a nostalgia trip. Many years ago I had a Sheridan Blue Streak. I had bought it
out of curiosity because it had a reputation as the epitome of American pump-up airguns. I developed a love-hate
relationship with that gun. Loved it's light weight, hated trying to find 5mm pellets for it (not a big commodity
item in Australia at that time), did not enjoy pumping it up and was disappointed in the mediocre accuracy. My
dad rubbed salt into the wounds by buying a Benjamin pump-up in .177 caliber and promptly shot rings around my
efforts with the Sheridan. One lives, one learns, one's memories linger on.
When Crosman acquired the Benjamin-Sheridan organization a few years ago, I began to wonder
what new directions the traditional American pump-up airgun would take. A few months back I spotted the new Benjamin-Sheridan
397 sitting on the shelf in K Mart. It took a couple of weeks of tossing with memories and curiosity before I bought
one; a delayed impulse.
Unlike European manufacturers that concentrate on high performance, mid to high cost adult
airguns, American manufacturers have mainly targeted the lower cost youth market. There are notable exceptions
such as Swivel Machine Works Inc. that produce some extremely "serious" airguns, but most from Crosman
and Daisy are entry level airguns, with several models almost being toys (potentially dangerous toys nonetheless).
Daisy do import several adult level airguns however. Benjamin-Sheridan represent the high-end of US airgun manufacturing,
which in the world market, is at the entry level to adult airguns.
The Europeans have concentrated on spring powered airguns in the past. More recent airgun
designs tend to be either pre-charged pneumatics (PCP's), single stroke pneumatics and most recently, thanks to
de-regulation caused by the paint-ball industry, CO2
repeater pistols. American manufacturers complement these airguns by producing mainly pump-up pneumatics and CO2 guns. Prices seem to be complementary also; it is like an International
marketing agreement where the boundaries have been clearly defined.
One speculates on such things as one gets older; back to the gun in review:
The Benjamin-Sheridan 397 is not an expensive airgun; presently priced at around $100. It
is very good value for money. Built from brass, steel and alloy with an American Walnut stock and stainless steel
bolt, there are no exposed plastic parts. Quality materials.
The pump-up (or multi-stage pneumatic) design is relatively simple. Take a long pump tube
with a multi-link pump lever, fit an inlet valve with air chamber towards the rear, strike an exhaust valve with
a spring driven hammer from the rear, fix a barrel on top and a trigger underneath and fit the whole with elegant
walnut stock pieces. A very clean design.
Benjamin-Sheridan
owners may notice something different in the above photo. The trigger. This airgun, if I interpret the first three
digits of the serial number to be a month-year prefix, then 997...... is a recently made example. All previous
Benjamin-Sheridan air rifles had a thin silhouette steel trigger guard; this gun has a chunky alloy casting. It
was the first thing I noticed when opening the box, and the first thing I noticed when firing the gun.
My first shot with the 397 sounded something like: "clap, clap, clap", (pump it
3 times), "eeee, click", (open the bolt and cock it), quiet, (drop pellet in breech), "scrit, scrat,
errrrr!!!!" (pulling trigger), "twoing, phutt!" (hammer spring noise and discharge). Less than 10
shots later my mind was screaming "that trigger has to go!!!". Out with the toolbox.
This new trigger mechanism looks like it was designed by a heavy duty locksmith!
The
trigger is a monster piece of metal. The design is extremely simple; a quick look at the photo and you can quickly
determine the mechanics of the design. (The top extension tang to the trigger moves in a space made by flat cut
into the bolt to prevent trigger discharge with the bolt open.)
The two sides of the trigger block are from cast alloy with a sprayed finish. No obvious
attempt had been made to smoothen the contact surfaces between the trigger piece and the alloy sides. This was
the cause of much friction and the very gritty, broken glass feeling. The photo shows the surfaces shiny after
polishing. Lubricate the pins with grease (they are a loose fit) and reassemble the unit. The trigger now felt
acceptably light when the trigger was pulled. Mount it on the gun, cock it and, uh, oh, still heavy and a noticeable
sticky point was there.
Pull the trigger apart again and examine the contact surfaces between the sear and hammer.
Burrs on both. Hone and polish. Reassemble and apply moly grease to the sear and hammer contact surfaces - something
never done with European triggers! Also put some spring gel on the hammer spring to quieten the "twoing".
Now the trigger is smooth and crisp, but lets off at 7lb pull; lighter than before, but still
much heavier than the 2.25lb I have my BSA rifles set to. It can be dangerous to use a gun with a heavy trigger
then switch to a gun with a lighter one. Still not happy.
I spoke to an air gunsmith and learned that the trick with the older style triggers was to
remove the spring behind the trigger, which was in a slot in the stock. OK, pull the trigger apart again and remove
the coil spring from behind the trigger. Reassemble and oops! The bolt would not cock without the trigger being
held forward by the finger. Put the spring back.
Except for redesigning the trigger to give the sear more mechanical advantage to pull away
from the hammer, I don't know what else can be done to improve it.
On the positive side, the trigger mechanism is definitely robust!
Also in the photo above, you can just see part of the rearsight. To say that the Benjamin-Sheridan
rearsights are adequate is just being kind. They are probably the first things to be removed by any shooter aspiring
to accuracy.
Fortunately a very acceptable Williams aperture sight is available for the Benjamin-Sheridans
and it readily fits into the machined and tapped flat on the right hand side of the receiver.
The
only complaint with this aperture sight is that unlike the Beeman sights, the Williams sight for the Benjamin-Sheridan
does not come with the option of thumb knobs. I find windage adjustment on this simpler style sight something of
a hit and miss affair. Loosen two screws, slide the windage piece and retighten the screws hoping that your guess
is right and that tightening the screws hasn't moved the slide. Elevation adjustment is more controllable because
the elevation screw provides a positive vertical stop.
Many years ago I learned with the Sheridan Blue Streak that only a masochist would fit a
telescopic sight to one of these guns. The problems with 'scopes are twofold:
Fortunately, I prefer aperture sights for target shooting, and once adjusted, the sight on
the 397 is very effective.
To the shooting range at last.
Benjamin-Sheridan state that 0.5" groups at 10m are normal. I find that claim perhaps
a little conservative. A 397 with a smooth trigger, good sights and the right combination of pellet and number
of pumps can probably shoot much tighter. I get around 1/8" to 3/8" groups at 6 yards from a standing
position. I'm not a benchrest shooter. The wider groups are usually just after using one of my BSA rifles and I've
not re-adjusted to the heavy trigger on the 397. I only use 3 pumps at this range.
Harking back to the Sheridan Blue Streak. With 6 pumps, 1.5" groups at 20 yards were
about all I could ever muster. That was with those dubious 5mm trash can pellets. 8 pumps opened the groups to
2" or more; so pellet design and stability was possibly a problem. Unfortunately there were no 5mm (0.20")
pellet alternatives available, so I never did determine if it was pellet design that was ruining accuracy. My dad's
Benjamin shooting 4.5mm Marksman pellets gave sub 1" groups under the same conditions.
The number of pumps will affect accuracy. Depending upon: pellet weight, shape and fit in
the bore; more pumps may widen up the groups, keep them the same, or maybe close them a little. With a pneumatic
airgun, there is usually an amount of excess air that is exhausted from the barrel as the pellet leaves the muzzle.
The design of a pneumatic must balance between air pressure and air volume. Modern single pump airguns have a "total
loss" or "total dump" valve design that exhausts all of the air in the valve box on firing the single
shot. But that is a very small amount of high pressure air. Pre charged pneumatics (PCP's) have a controlled exhaust
valve with a very carefully regulated amount of very high pressure air being discharged; that way tens of shots
may be fired before recharging.
The Benjamin-Sheridans employ a total dump valve system of relatively high volume and low
to moderate pressure. Historically this system worked very well with large calibers and long barrels because the
large volume of air has a large working surface over a long distance in which to accelerate the pellet, ball or
bullet. Witness the large bore military air rifles of the past. Small calibers and short barrels are not nearly
so efficient. The 397 is a fair compromise between barrel length and caliber if it is not over pumped. The relationship
between number of pumps and muzzle energy is not linear. Twice the number of pumps does not yield twice the muzzle
energy. Often, more pumps will give a noticeably louder exhaust noise; more noise is more power being vented; that
is: it was not all transferred to the pellet. An excess of muzzle blast may also cause instability to the departing
pellet. If the muzzle blast is of higher velocity than the pellet, and the pellet is of very light weight, it may
be tumbled a little. Accuracy will suffer.
So, more pumps, more work for you, more noise and possibly less accuracy. Heavy pellets over
longer ranges will probably be more accurate than light weight pellets over the same range when the gun has been
pumped to eight and the energy transfer will probably be better.
Just when I thought I had some idea of airgun ballistics, I start playing with a multi-pump
pneumatic, and have a whole new world of variables to consider. Live and learn!
Chronograph testing a pump-up airgun is something of a chore. Start with 3 pumps each for
a 10 shot string; that's 30 pumps. Then for 10 shots at 6 pumps; add another 60 pumps of the gun. After pumping
90 times, one gets a little weary when 8 pumps per shot are contemplated; cheat a little and average the first
3 shots that show minimal variation! Here's some results from shooting 7.40 grain RWS Super Hollow Points:
|
Pumps
|
Average Velocity fps
|
Average Energy fp
|
|
3
|
569.57
|
5.33
|
|
6
|
725.03
|
8.64
|
|
8
|
777.56
|
9.94
|
It is easy to see that the 397 is most efficient at 3 pumps with this pellet. Doubling the
number of pumps did not double the energy. In fact, 8 pumps did not double the energy either.
Using the heavier, 9.50 grain RWS Super Mag pellets at 8 pumps yielded an average of 714.44
fps for 10.77fp. It does take a heavier pellet to get the energy back out of more pumps!
I'm quite content with the performance and accuracy with 3 pumps. If I need more power for
longer range shooting, I reach for one of my spring airguns.
During all of this shooting, I became aware that the stock was slipping around on my shoulder
a bit. Examination of the butt on my 397 showed a very smooth finish to the timber. I almost dashed off to get
a rubber butt plate, thinking "what modern gun has a bare timber butt on it's stock". The Benjamin-Sheridan
is possibly the only gun in production with a bare butt. Most vintage guns do not have a butt plate, so if they
worked, the problem must be the slippery finish. Grab some medium sand paper and rub the surface transversely until
the finish is cut through to the wood, follow by a wipe of Lemon Oil, and what a difference! No more slip off the
shoulder.
I also found that with pump-ups holding the gun by the pump lever forearm whilst shooting
is not a good idea. There is an inevitable amount of play in the pump linkages when the gun is discharged. When
pumped up, that slop tends to disappear if enough residual air is left under pressure between the pump head and
the inlet valve. Upon discharge, that air may escape through the valve and the pump forearm relaxes a little. This
can be enough to affect accuracy, not much perhaps, but it does happen. I find that holding the gun with the fingers
of the left hand resting just on the gap between the stock pieces, gives me the most accurate shooting stance.
There is a cautionary note for Benjamin-Sheridan owners. My gun has the words: "AIR
HOLE DO NOT OIL" stamped under the pump cylinder. I thought that odd, since one normally oils pump pistons.
An air gunsmith told me that Benjamin-Sheridans now have an air valve that can suffer hydraulic lock if oil gets
into them. Ouch. The gun will lock up. The only way to unlock it is to have an air gunsmith disassemble the gun
and free the valve. Apparently the older style valves did not do this.
Synopsis
I like the look, feel and finish of the new Benjamin-Sheridan 397. It's fun to shoot and
very accurate under the conditions I use it. If only it had a better trigger...
What I do miss a little is the plastic hand grip that slipped over the barrel of the old
Sheridan Blue Streak; it saved getting a barrel impressed in your hand during extended pumping. What I don't miss
is the thin finish on the old Blue Steak; after a bit of use the brass would show through where it was held for
pumping. The new guns have a much thicker and more durable looking black finish.
If you want a low cost, good quality training and plinking air rifle, then the Benjamin-Sheridan
is an excellent choice. Just don't expect to pump it up to Magnum air gun standards.
Technical Features Benjamin-Sheridan 397PA .177 Cal.
| Feature |
|
| Weight |
5.5lbs (2.5kg) |
| Overall Length |
36.25" (921mm) |
| Muzzle Energy (measured; expected) |
Variable up to 11FP (up to 14.91J) |
| Muzzle Velocity |
800fps (244mps) (advertised) |
| Accuracy |
0.50" c-t-c @ 11yds (advertised) |
| Stock |
American Walnut, 2 piece |
| Barrel Length |
19.375" (492mm) |
| Barrel Mounting |
Fixed over air pump tube. |
| Trigger |
Two stage non adjustable. (Typically over 7lb pull) |
| Scope Mounting |
Sheridan Intermount accessory for 'scope. Pre-drilled for aperture sight. |
| Air Cylinder |
Brass tube |
| Silencing |
None |
| Cocking Effort |
Variable, increases with number of pumps. |
| Anti-Bear Device |
None (Manual Cross Bolt Safety) |
| Uncock without firing |
No. Can be dry fired. |
| Price Range (New, variable!) |
$100.00 to $120.00 |
Post Script:
The heavy trigger pull once again annoyed me after a shooting session with my British airguns.
I pulled the trigger unit off the gun and measured the pull required to overcome both stages:
1.25lb. Obviously the problem is with the drag between the sear and the hammer; even so, 5.75lb of drag did seem
excessive. On closer examination the problem became obvious. The sear is cut vertically to have a parallel contact
with the hammer surface. This is not good when the sear is rotated downwards - the swing arc about the sear pivot
actually requires the sear to move the hammer backwards. Effectively the added trigger weight is caused by having
to push against the hammer spring. (Do NOT tamper with the hammer spring; it's balance is required for correct
gun discharge.)
Out with the Dremel and polish the sear to a slight arced contact surface (jig and rotate
the sear about it's pivot point while polishing.) I was a bit conservative - too much and the hammer may force
the sear down and be unsafe. The trigger now releases at 4lb. A lot better! Not quite as light as I would like...
how long before I polish a little more?
The new Benjamin Sheridan trigger has potential for much better performance than it does
out of the box.