Resealing the Daisy model 41 pellet pistol: Part 2
by Tom Gaylord
Writing as B.B. Pelletier
Today’s report is another guest blog from reader Ian McKee who writes as 45 Bravo. Today and tomorrow he will tell us of his experience in resealing a Daisy model 41 pellet pistol.
If you’d like to write a guest post for this blog, please email me at [email protected].
Resealing the Daisy model 41 pellet pistol: Part 2
Now, take it away, Ian.
Writing as 45Bravo
This report covers:
- Parts breakdown
- Trigger and hammer
- Valve body
- Valve parts
- The reseal
- Leak test
- The service manual minimum specs are listed as:
- Some things Daisy got right with the 41
- What was Daisy thinking?
- A treasure trove of information
Today we start with the disassembly of the Daisy model 41. Removing the barrel and velocity adjuster is the similar to the Daisy 790 in part 4 of the 78G blog, except the crosspin that holds the end cap that contains both the front of the barrel and the power adjuster in the “slide” is splined on one end, so it goes in only 1 way.
The 41 barrel and velocity adjuster remove the same as the 790’s parts.
The pin that holds the barrel and power adjuster end cap is splined on one end, so it only fits in one way.
At this point it is useful to give you an illustration of all the parts. Ellarge the page to see it better.
The 790/41 parts breakdown provides a map to follow the rest of the disassembly.
Trigger and hammer
The trigger and 2 piece hammer system is the same as the 790 that was shown shown in Part 4 of the 78G blog.
This is the underside of the two-piece 41 hammer, similar to the 79G hammer shown in Part 4 of my blog on the 78G and 79G.
The rear of the slide is held on by 1 screw on the right side of the pistol, just like all of the earlier pistols.
The valve body (part 790-312-A) is made from zinc or pot metal, the valve assembly is held in by 4 screws, not 3 screws like the earlier design.
The completely assembled valve assembly as a whole is part number 790-32.
If you wanted to order the individual parts, you have to add the letter designation, such as 790-32-F for the main seal, and 790-32-C for the main valve body seal.
This is the valve assembly, complete.
The model 41 valve, assembled.
The transfer port seal (part 790-31) is nylon, like the one on the 790 we looked at in part 4 of the 78G blog, it seals the barrel/valve very well, with no leaks or puffs of air when fired. Its slightly oversize design, allows for some misalignment with the barrel port, but still seal where they join.
The transfer port seal on top of the valve seals the valve to the barrel.
Now let’s look at a drawing of the valve parts.
This portion of the parts breakdown shows the valve parts with their letter designations.
There is a protrusion cast into the valve body that holds the trigger spring in place during assembly so you don’t need an eleventh finger, or zip ties during assembly. You see it in the drawing above.
Because the valve body and piercing assembly are together, there is no cartridge connector connecting the valve body to the frame. This is where the Daisy engineers simplified the S&W design and reduced the parts count.
There is a steel pin (part 790-32-G — refer to the previous drawing) that holds the valve body cap (which Daisy calls the valve plug) in place, when you drive that out, the cap/plug is under a few pounds of spring pressure and will come out the back like the earlier designs.
Definitely not the same
The steel valve stem and nylon main seal (parts 790-32-E, and 790-32-F respectively) are 2 pieces, unlike the older design, where the seal and stem were 1 piece.
Valve stem and seal.
This is a simpler design, and more cost efficient to produce.
Only 1 o-ring from the Smith & Wesson seal kit will work on this gun, and that is the main valve body o-ring that fits on the valve plug.
The bolt probe o-ring is thinner in diameter than the normal .177 bolt probe o-ring, and the groove on the bolt probe is narrower than the other .177 bolts.
The model 41 bolt probe o-ring (right) is thinner and larger than the 79G bolt probe o-ring.
Whoever said the internals were the same, has never been into one of these!
The valve body plug o-ring is straightforward. It is a number 012 o-ring, and is captive, so it can be any type of o-ring you want to use. But personally I use urethane as they are impervious to CO2.
I have never seen a seal like the one used as the main seal, if anyone here knows a source for them, or if they were used in a different model Daisy made, please let me and Tom know, so he can update the blog with the info, and I can get a few for future repairs .
The main seal in the valve looks proprietary to me. If you know where they exist anywhere else, please let me know!
Daisy’s service manual tells you to dig the main seal out with a sharpened piece of music wire bent into a hook. If the main seal deteriorates, (part 790-32-F in the parts diagram) at this point in time, good luck finding a replacement.
The seal drops in the valve body, flat side facing the front of the valve, the valve stem (part 790-32-E) goes next, the valve spring, the valve body cap, and the steel pin holds it all together.
The main seal goes into the valve first, followed by the valve stem assembly.
The OEM CO2 face seal (part 790-43) is available online. The company that sells the OEM face seals, limit you to only 3, until the OEM parts came in, I used replacements I had on hand to test the gun, it is apparently the same size as used in several models of CO2 magazines of modern 1911 air pistols.
The face seal is installed.
If you unscrew the CO2 piercing piece, there is a small o-ring inside there, (part number 36 in the diagram). I do not know the size of it, but it was flat, kind of like a small rubber band used by kids with braces, but smaller, and made from black rubber.
After assembling the valve, it’s easy to assemble the rest of the pistol. Put the trigger spring on the protrusion on the front of the valve, line it up with the trigger, and insert the valve into the frame. Secure it with the 4 screws.
Daisy added 4 small pads cast into the frame around these screws to strengthen the frame at this point. Since the frame is thicker, it SHOULD not crack like the older frames if the screws are too tight.
The pads Daisy added to the frame can be seen around the screw holes for the valve.
Insert the plastic transfer port into the valve body, replace the bolt probe o-ring if needed, and assemble the “slide”. I suggest setting the power adjuster to a preset position, before assembly, as it is plastic, and easily damaged by a screwdriver while trying to adjust the power.
As you can see, the power adjuster of the 41 is all plastic and doesn’t hold up to being adjusted. It’s best to set it where you want it before you assemble it into the pistol.
The power adjuster parts are plastic. Set them where you want and just leave them alone after the pistol is assembled.
Secure the slide to the frame with the single screw on the right side.
Insert the muzzle plug that holds the barrel and power adjuster (part 790-4).
Then insert the power adjuster assembly into the bottom hole of the muzzle plug, making sure the groove for the retainer pin uses is towards the barrel, then reinsert the splined retaining pin.
On this gun, the pin goes in from the right side of the gun, but the diagram shows it going in from the left side. You want those splines going into the gun last.
To check for leaks on this model, after charging the gun with CO2, put some light oil (I used Crosman Pellgunoil), where the valve stem comes out of the valve, and some where the valve body cap is in the rear of the valve, and some on the area where the piercing pin and face seal screw into the bottom of the valve. Look for bubbles to form.
Performing the leak test.
If there are no leaks in the oil (arrow), put the grips back on the gun and function test.
Since this model uses a face seal, the CO2 cartridge goes in with the flat end up toward the top of the pistol. Tighten the CO2 cap at the bottom of the grip to pierce the cartridge. With this type of cartridge arrangement, it is suggested you not leave a cartridge in the gun, as the face seal will eventually lose its shape and start to leak prematurely. But the service manual does say to leave it charged for 24 hours, then test again to see if it still holds gas, and shoots to same velocity in the initial test after repair.
The service manual minimum specs are listed as:
The first 20 shots from a new co2 cylinder are as follows:
With the velocity adjustments set to max.
Room temperature between 70-85 deg. F.
(They don’t specify what pellet or pellet weight.)
S&W78/79G, Daisy 780-790 Phase I&II:
780 320fps (98mps) minimum velocity.
790 330fps (101mps) minimum velocity.
Phase III and Model 41:
780 340fps (104mps) minimum velocity.
790 420fps (128mps) minimum velocity.
41 420fps (128mps) minimum velocity.
Some things Daisy got right with the 41
They added metal to the valve support screw area to prevent cracking.
Simplified the valve, and reduced the parts count, and o-ring count.
Nylon Transfer port seal instead of metal to metal port like the S&W.
They added a trigger spring support to make assembly easier.
They added a middle position to the bolt probe so it can be in 1 of 3 positions, closed and ready to fire, partly open but the o-ring not compressed for storage, and open for loading.
What was Daisy thinking?
The entire bolt assembly and probe are made entirely from plastic!
Plastic rear sight assembly.
A new seal system for which, as far as I know, no replacement parts are available.
A plastic power adjuster that is easily damaged when adjusted.
A plastic co2 cap.
A treasure trove of information
With this reseal, we have learned the facts of what is and what is not inside a Daisy Model 41. We also now have a copy of the owners manual, and we now have an actual exploded parts view, and factory service manual. [Editor’s note: I have no place to put this entire manual — yet. I will work on it.
With this information, hobbyists will be able to repair and reseal their pistols and have at lease some idea of what they are up against before they start.
If you have any information that would be helpful, please post it.