Crosman Town & Country 107

[jirushi]

Well, to adjust your pump arm without proper over toggling would result in a "droopy" forearm lever... which I cannot abide. ;-)

The forearm lever is still droopy hehe.
Tonight I finally had some time to work on the 107 again, after all the Christmas parties.
I have the (man?) flu, so I will have plenty of airgun tinkering time

Right, I tested several pump rod length settings.
Greater length, even past the point where the air hole "works", still wouldn't cause over toggling.
Whilst closing the pump arm, I could still see movement of the pump rod, which I think means that it hadn't hit the valve wall yet.
When there's no air in the valve, the pump doesn't stay in place.
After 1 pump, with the gun being cocked (so that air stays in the valve), the pump arm does actually stay in place.
Is the air bubble in front of the pump cup giving the required contra pressure for over toggling to happen?
I also wondered if there might have been a ring in front of the valve wall, when the gun was built? A ring that makes contact with the pump cup, so that over toggling takes place? I don't know.

What I do know is that the maximum velocity that I found previously, 545 ft/s with 8 pumps, is the maximum velocity that I have found today too. Exactly 545 ft/s again. Will try lapping the probe at some point. For now I'm ok with the droopy lever, it doesn't affect my masculinity too much
One last question that I have: in the pump arm assy, there is a spring. Does the strength of this spring have any effect on the pump arm closing ability?

Oh, in DT Fletcher's book "The Literature of Crosman", there are some great photos of T&C ads and of General Hinds and Mr. P. Y. Hahn looking at the new T&C rifle.
I'm not sure if I may share them on here though.

[45flint]

I checked my 108 and forgot that there is a leaf spring inside the cocking arm that supports it as it closes. Maybe that spring is stuck or damaged? On my 101’s as well. I think they eventually did away with these but have no idea when. 545 FPS isn’t out of line?

[jirushi]

Yes I have a feeling that the leaf spring in my 107 pump arm needs to be replaced. It doesn't appear to be stuck or damaged, but it might just be weakened by use and time?
I agree, 545 is nice. In .177, that means a pretty good plinking range.

[DT Fletcher]

It can be difficult to gauge proper pump setting with the internals (exhaust valve, etc) working; which is why I usually set the pump while the internal components are still out. However, what can be done is to take down the gun to the point that you can access the exhaust valve and simply press it in while setting the pump head space. With no back pressure, it's easy to feel when the pump head hits the compression chamber.

Yes, the air pressure left in the air space from an improperly adjusted pump will hold up the pump arm.

Pump arm droop is a clear indication that the gun is improperly adjusted and will not -cannot- operate to full potential. Plus, it's embarrassing.

[--ped--]

an easy way to rough set the piston so it cams over is to get a bit of 1/2" dowell or rod and in sert it down the compression tube till it hits the valve
then mark the rod through the lever pivot pin hole
once removed fit the piston to the rod line the pivot pin hole up on the rod and lever and adjust the piston till it's flush with the end of the rod or a mm longer to allow for wear in the linkages
tis will give you a starting point
another tip is to use a 3/16" punch in place of the roll pin
the spring steel in the lever is designed to keep the lever up with no air pressure and was later swapped to a plastic button in the lever that used friction between the two parts of the lever
Sheridan and Benjamin kept using the spring steel in the lever as they stopped using an adjustable piston rod in the early 60's(sheridans not sure on date for when Benjamin did)

[45flint]

an easy way to rough set the piston so it cams over is to get a bit of 1/2" dowell or rod and in sert it down the compression tube till it hits the valve
then mark the rod through the lever pivot pin hole
once removed fit the piston to the rod line the pivot pin hole up on the rod and lever and adjust the piston till it's flush with the end of the rod or a mm longer to allow for wear in the linkages
tis will give you a starting point
another tip is to use a 3/16" punch in place of the roll pin
the spring steel in the lever is designed to keep the lever up with no air pressure and was later swapped to a plastic button in the lever that used friction between the two parts of the lever
Sheridan and Benjamin kept using the spring steel in the lever as they stopped using an adjustable piston rod in the early 60's(sheridans not sure on date for when Benjamin did)

Thanks for that, I have a new pump rod coming and my old one is already off.

[jirushi]

an easy way to rough set the piston so it cams over is to get a bit of 1/2" dowell or rod and in sert it down the compression tube till it hits the valve
then mark the rod through the lever pivot pin hole
once removed fit the piston to the rod line the pivot pin hole up on the rod and lever and adjust the piston till it's flush with the end of the rod or a mm longer to allow for wear in the linkages
tis will give you a starting point
another tip is to use a 3/16" punch in place of the roll pin
the spring steel in the lever is designed to keep the lever up with no air pressure and was later swapped to a plastic button in the lever that used friction between the two parts of the lever
Sheridan and Benjamin kept using the spring steel in the lever as they stopped using an adjustable piston rod in the early 60's(sheridans not sure on date for when Benjamin did)

Hi ped, thank you for this excellent advice.
Very useful.
I will do this.
I'll wait for my pump rod from JG Airguns to arrive first.
It's still strange that I didn't feel the pump cup hitting the valve when I adjusted the pump rod to maximum length. Or I missed it.
We'll see.
I do believe that the fact that my pump arm drops down when there is no pressure in the valve, is caused by a worn spring steel in the lever.
So further pump rod adjustments will be aimed at getting more efficiency (power).

@junglie, thank you. In the case of this 107, I would not like to store it with air in the valve, because the hammerspring needs to be tensioned (the gun cocked) to do so.
In the uncocked state, the hammer presses against the exhaust valve, and air simply escapes through the barrel when pumping.
I think the best way to maintain guns like the 107 and 108, is to shoot them regularly.
On the other hand, as 45flint pointed out earlier, a reason for this 107's relatively good survival might be the fact that it didn't work!

[45flint]

@junglie, thank you. In the case of this 107, I would not like to store it with air in the valve, because the hammerspring needs to be tensioned (the gun cocked) to do so.
In the uncocked state, the hammer presses against the exhaust valve, and air simply escapes through the barrel when pumping.
I think the best way to maintain guns like the 107 and 108, is to shoot them regularly.
On the other hand, as 45flint pointed out earlier, a reason for this 107's relatively good survival might be the fact that it didn't work!

Actually you can leave a couple pumps in to store your 107. I cock my bolt, put two pumps in, then holding the bolt I pull the trigger and slowly lower the bolt. It will rest on valve and not trip it. Mine stores those two pumps indefinitely.

[junglie]

The forearm lever is still droopy hehe.
Tonight I finally had some time to work on the 107 again, after all the Christmas parties.
I have the (man?) flu, so I will have plenty of airgun tinkering time

Right, I tested several pump rod length settings.
Greater length, even past the point where the air hole "works", still wouldn't cause over toggling.
Whilst closing the pump arm, I could still see movement of the pump rod, which I think means that it hadn't hit the valve wall yet.
When there's no air in the valve, the pump doesn't stay in place.
After 1 pump, with the gun being cocked (so that air stays in the valve), the pump arm does actually stay in place.
Is the air bubble in front of the pump cup giving the required contra pressure for over toggling to happen?
I also wondered if there might have been a ring in front of the valve wall, when the gun was built? A ring that makes contact with the pump cup, so that over toggling takes place? I don't know.

What I do know is that the maximum velocity that I found previously, 545 ft/s with 8 pumps, is the maximum velocity that I have found today too. Exactly 545 ft/s again. Will try lapping the probe at some point. For now I'm ok with the droopy lever, it doesn't affect my masculinity too much
One last question that I have: in the pump arm assy, there is a spring. Does the strength of this spring have any effect on the pump arm closing ability?

Oh, in DT Fletcher's book "The Literature of Crosman", there are some great photos of T&C ads and of General Hinds and Mr. P. Y. Hahn looking at the new T&C rifle.
I'm not sure if I may share them on here though.

It's good practice to store pump guns with a pump or two in to preserve the valves from the ingress of dust so that would keep your droopy arm closed.