I recently purchased a 1st variation 150 and after resealing it and testing it for
velocity, I found the velocity to be a bit low... at least in my mind. The power
adjustment on the earlier hammer assemblies was accomplished by turning the
cocking cap clockwise to increase and counterclockwise to decrease the power.
My resealed gun had velocities of: 355 High & 293 Low, using Crosman 14.3 HP
pellets.
The hammer assembly on the early model guns, didn't have the heavy outer
hammer spring like the later models, but rather, a small diameter spring around
the cocking rod, that fit inside the hammer pocket. I figured the old hammer
spring was weakened from being stored cocked for years on end, (70?) and
thought I would just replace the spring with a new, maybe heavier one.
Question was, how to get the hammer assembly apart? Online was no help, as
all of the forum responses I read were, "I tried, but couldn't figure it out."
So, I figured it out...
This is only for the earlier model guns where the cocking cap is screwed on,
not pressed on. You can easily tell what you have by pulling back the cocking
cap and looking to see if there is a large hex nut visible against the cocking
cap. That nut is threaded onto the cocking rod along with the cocking cap.
If so, then you're go to go.
Disassembly procedure...
The larger disc end of the cocking rod, is hardened steel and could be easily
held secure with a pair of channel lock pliers without damage. The cocking cap
is not so hard and will get damaged if not protected. I wrapped mine with a
heavy piece of leather to protect the metal and then, used another pair of
channel locks on it to break it free. If the cap spins in the leather, tightly wrap
a rubber band around it and then wrap it with the leather. The rubber band will
grip the metal better than the leather alone. Once cracked loose, the cap spun
off with my fingers. Over the hex nut is an internal lock washer. The hex nut is
3/8" and requires a socket to easily remove it. There was no sign of any sealant
or Loctite on any of the threads. Once the hex nut is removed everything just
shoots apart, "Under spring pressure!"
Reassembly is in reverse order, of course.
Improved velocity...
I tried the same length spring with a few thousands larger wire diameter and
the same coil count as the old spring. It worked OK on the low end, but when I
increased the power to maximum, the cocking knob was almost too hard to pull
back. That was a no-go for me. I decided to use the old hammer spring and add
some spacers to increase the preload. I found that (3) M5 metric flat washers
worked perfectly between the hammer spring end washer and the tube plug.
It almost doubled the preload and increased the velocity nicely without a
noticeable increase in the effort required to cock the gun.
Before & After...
With Spacers - High = 409 fps, Low = 359 fps, Velocity Spread = 50 fps
Without Spacers - High = 355 fps, Low = 293 fps, Velocity Spread = 62 fps
Net Gain in FPS - High = 54 fps, Low = 66 fps.
The later model 150's with the dual cocking hammer assemblies seem to have
much higher velocities due mostly to a heavier hammer spring, I think. I have
no way of knowing that firsthand, but that is what I gathered from reading
velocities quoted in some of the forums I have read, and everyone knows that's
gospel!
So, the 1st variation 150 isn't a powerhouse when compared to the later model
150 or even a 2240, but hey, give the old man a break!
H&BGuy
