Daisy 880 Mods in Progress:

[DavidS]

Now that I am going to begin modifying my Daisy 880 I feel that I should start a new thread describing the process as it happens.

This gun has exceeded my expectations for the gains to be had in simple modifications thus far.

So here is the list of mods todo:

PUMP NOISE:
1: *DONE* Add a bit of felt where the pump arm hits the metal casing.
2: *DONE* Shave the nob on the pump handle where it engages the hold spring.

ACCURACY:
1: *DONE* Wrap the end of the barrel in electrical tape to make it fit the shroud better.
2: *DONE* polish the trigger hammer contact surfaces.

POWER:
1: *DONE* Fill the slot in the end of the piston with some epoxy.
2: *DONE* Reduce the strength of the spring on the inlet.
3: *DONE* Reduce the strength of the spring on the outlet.
4: *DONE* Stretch the hammer spring to cause faster opening of valve.
5: *DONE* Create a shim to eliminate most of the head space in front of the piston O-Ring when closed.
:: The following items will not be done, as I have already a better gun than I thought I could get out of the Daisy 880 .
6: Create a shim to reduce the head space in front of the check inlet cup seal till the flat metal of the check inlet valve.
7: Add a bit to the hammer to cause earlier contact.
8: Drill the transfer port out to .140, and polish.
9: Remove a little material from the valve body to increase the internal volume of the valve assembly.


SAFETY:
1: Secure the pump tube in place better.  Still looking at the best way to do this.
2: Seal the port from the BB feeder into the breech.
3: seal the BB feeder cover.


I will post updates of the progress and results as I go.

Below are the progressive numbers as the power Modifications are done.
All numbers are the average of 5 shot groups

And of course:
YMMV
Each gun will be a bit different do to manufacturing tolerances, the price of mass production.

At 8 pumps before any mods with Winchester 9.63 grain Pointed Pellets.
603FPS = 7.8FPE
At 12 pumps same pellet:
684FPS=10FPE

And After filling the slot in the piston head:
At 8 pumps with Winchester 9.63 grain Pointed Pellets:
622FPS = 8.3FPE
At 12 pumps:
714FPS = 10.9FPE

And After Lightening the valve springs and stretching the hammer spring:
At 8 pumps with Winchester 9.63 grain Pointed Pellets:
634FPS = 8.6FPE
At 10 Pumps:
687FPS = 10.1FPE
At 12 pumps:
730FPS = 11.4FPE

After creating a Delrin shim to sit in front of the O-Ring on the piston (winchester 9.68grain pointed pellets):
4  Pumps = 482FPS = 5FPE
8  Pumps = 654FPS = 9.2FPE
10 Pumps = 711FPS = 10.9FPE
12 pumps = 749FPS = 12FPE

I must recommend AGAINST any one doing any modifications to there air gun, as this can be dangerous.

So please let me know of positive results in modifying your Daisy 880, 901, or Winchester 77x .

I hope that this also gets some more people interested in the possibilities with the Daisy MSP Air guns

[mudduck48]

Looks like you are on your way to an 880 master piece. 

[DavidS]

Now for where it stands.  The mods that have been done so far:

*DONE* Add a bit of felt where the pump arm hits the metel casing.
RESULT:  Makes the closing of the pump arm a lot quieter.

*DONE* Shave the nob on the pump handle where it engages the hold spring.
RESULT: Makes both the closing and opening of the arm a lot quieter.

*DONE* Wrap the end of the barrel in electrical tape to make it fit the shroud better.
RESULT: I can not comment as I did this before shooting the gun.

*DONE* Recrown barrel.
RESULT: I can not comment as I did this before shooting the gun.

[DavidS]

Looks like you are on your way to an 880 master piece. 

I do not know about that.  We will see.

Thank you.

[DavidS]

*WIP* Fill the slot in the end of the piston with some epoxy.
Today I am filling the hollow space in the middle of the piston.
Will report results.

[bradyman1]

Looking forward to your results. Post up some pics of those power mods.

[DavidS]

*WIP* Fill the slot in the end of the piston with some epoxy.

While I wait for the epoxy to set here are before and after pictures of the filled slot in the piston.

[DavidS]

*DONE* Fill the slot in the end of the piston with some epoxy.

And it shoots well.   I will get some numbers later today.

[K.O.]

That is also a common 953/853 mod but my piston was flat topped so I took up valve space.

[DavidS]

That is also a common 953/853 mod but my piston was flat topped so I took up valve space.

Thank you for that.  I will remember that if I get a 953 or 853 in the future.

Also have you done anything more to yours?   Any new numbers to report?

[DavidS]

*DONE* Fill the slot in the end of the piston with some epoxy.

This made a much bigger difference than I expected.  This really makes me excited about what potential is in this gun .    And it still seems to shoot as accurately as before (so far).

Ok now for some numbers:
At 8 pumps before any mods with Winchester 9.63 grain Pointed Pellets.
603FPS = 7.8FPE
At 12 pumps same pellet:
684FPS=10FPE

And After filling the slot in the piston head:
At 8 pumps with Winchester 9.63 grain Pointed Pellets:
622FPS = 8.3FPE
At 12 pumps same pellet:
714FPS = 10.9FPE

The numbers presented are the average of five shot groups.

Attached a slightly better pic of the filled piston head.  I will work on a bit better photography in the future.

[DD789]

*DONE* Fill the slot in the end of the piston with some epoxy.

This made a much bigger difference than I expected.  This really makes me excited about what potential is in this gun .    And it still seems to shoot as accurately as before (so far).

Ok now for some numbers:
At 8 pumps before any mods with Winchester 9.63 grain Pointed Pellets.
603FPS = 7.8FPE
At 12 pumps same pellet:
684FPS=10FPE

And After filling the slot in the piston head:
At 8 pumps with Winchester 9.63 grain Pointed Pellets:
622FPS = 8.3FPE
At 12 pumps same pellet:
714FPS = 10.9FPE

The numbers presented are the average of five shot groups.

Attached a slightly better pic of the filled piston head.  I will work on a bit better photography in the future.

So I guess photography isn't one of your other hobbies? (not my intention to put you down just poking a little fun at your expense) at one time inspecting film for PC Boards with .003 width traces that had to have good sharp edges so when the artwork was exposed on the PCB material the traces wouldn't be under etched. So after looking for over 10yrs. peering through a 7X loupe and sometimes a 60X scope. I hope you don't take any offense at what I say. just to give you an idea of what I was using to look at the artwork with. by the way those are etched lines so if you wanted to know what a etched retical looks like for a scope.

[DavidS]

@DD789:
It is all good, I got a good chuckle out of that.

Yea Photography is not high on my list.  And using a composite camera with a true resolution of 720x480i does not help at all.

I realize the irony though:
I used a Crosman 2289g box as the bench to disassemble the Daisy 880 on (as seen in the pics).

[K.O.]

I might be able to smooth flow a bit but honestly do not think it will gain very much (5-20 fps?) I ended up taking a bit more than 1/3 of the

valve volume 1/2 was to much and I got 460-465 fps and 1/4 dropped fps to 445- 450. It took me 7 tries to find the right size.

There is one more thing I can do and that is tune the pump tube itself by adding  a .06-.07 shim to where it seats to the valve to maximize

stroke and still let it take in air. What a .07 longer stoke would get ?

I also used some wraps of Teflon tape  behind the o-ring that seals the pump tube to the valve to make sure that it seals it fit noticeably

tighter and there is much less pump tube movement.


I will probably leave it as it is for now at 495 fps with 7.9g CPHP because I do not have a spare valve in case I mess up  and further gains

would be from non reversible flow mods... but heck 70 fps from tuning valve volume is better than a kick in the rear...

[DavidS]

@K.O.:
Well those are definitely good results for improving a SSP.   Nice work.

I am amazed at what I am getting out of the Daisy 880 MSP.  And I am just getting started.  Have you ever tuned one of these for power?

[K.O.]

Ah found it scroll down a bit and there is a bit about getting the valve open quicker and farther...

http://www.airgunhome.com/agforum/viewtopic.php?p=22084

[K.O.]

I seem to remember there being a rubber thing on the piston that a friend changed to something stiffer, do the new ones still have that.

[DavidS]

Ah found it scroll down a bit and there is a bit about getting the valve open quicker and farther...

http://www.airgunhome.com/agforum/viewtopic.php?p=22084

Thank you for that.  I will be adding something along this lines to my mods.   This may turn out to be one powerful 880 .

[DavidS]

I seem to remember there being a rubber thing on the piston that a friend changed to something stiffer, do the new ones still have that.

Yes there is a rubber sleeve, though it seems quite hard as is.  I will look at that a bit more.  Thank you.

[stonykill]

 so far so good