Accurizing the Daisy 880

[jmcgall1]

Hey man how did you remove the powerline barrel from the reciever?

[nervoustrigger]

The barrel is held in the receiver with a friction fit.  I simply clamped the barrel carefully in my woodworking vise and just grabbed the receiver in my hand and separated them. 

The vise jaws are lined with wood so they are somewhat forgiving on the barrel.  Still, you don't want to use an excessive amount of clamping force since the barrel is thin. 

If you feel like you're having to clamp too tightly to keep it from slipping, modify the approach slightly.  Clamp two pieces of wood (e.g. some 2x4 scraps) together face-to-face and then drill a hole at the seam that is just slightly smaller than the barrel diameter.  1/64" or 1/32" smaller should be sufficient.  That gives you a close-fitting clamping die that you can load into the vise...something that hugs the barrel fully around its circumference.  That distributes the friction better so you don't have the clamping force concentrated on just two small spots like you get when using flat jaws. 

I hope that makes sense but if not, let me know and I'll go out to the shop and mock it up and get you a photo.

[jmcgall1]

nope that was perfect. I used a vice with wood i had drilled holes in to hold the barrel when i crowned it, simply leaving the receiver attached. I recently re-recrowned it, using a slightly better method of polishing.

 I also tried floating the barrel (simply remove the shroud), not that i expected it to be better. and while it didn't perform horribly it didn't really improve either as the barrel is very flimsy. Currently mulling over ideas to make a full wood stock and replacing the plastic dovetails with a stronger material. I've noticed I get a lot of two shot groups, where i get a pellet in pellet hole before the POI changes slightly, and i believe this is due to torquing of the plastics, changing the plane of the scope slightly. So if i could make a new dovetail that is secured to the receiver maybe it will improve the accuracy just slightly more. I also would like to create a new shroud, one that is supported by the receiver, but i'm not sure if that is going to happen or help.

I think a floated barrel helps a PCP gun as there is a slight expansion and contraction of the air reservoir and freeing the barrel keeps it from being affected by this expansion. The powerline has the shroud connected to a steel support, which is floating in respect to the air compression chamber so the shroud might not affect accuracy at all. I also have yet to solve any trigger issues, I can deal with it and it is heavy, but it would be cool to make it lighter. 

[nervoustrigger]

Yeah, I couldn't see any improvement from floating the barrel either.

Regarding the dovetail, I did not like how the whole thing is molded into one side of receiver housing.  In other words, it sort of reaches out over the opposite side, and when you tighten down on the scope mount, you've basically got a wedge trying to peel the dovetail away on one side.  So I installed a series of small countersunk screws through the top of the free-hanging side of the dovetail, down into the receiver housing, to firm it up.

[jmcgall1]

That's smart i was thinking of trying that, too. What I just did was dismantle the entire thing, took a bunch of measurements, and started to notice some engineering flaws and strengths. The "spine" of the gun does keep the shroud from being affected by any part of the gun, so that shouldn't be affecting the accuracy negatively

THE STOCK, however, is attached to the inner housing of the receiver, which is all attached to the spine by the two screws, which happen to be perfectly parallel to each other. This means that when you apply pressure to the stock, it causes the whole receiver to move and pivot around the screws. I used some half inch self tapping metal screws, which i then cut after they threaded as they were a little long. Also drilled out the plastic receiver slightly so that it would fit flushly over the screw heads, the fix isn't visible once the plastic is put back on.  Hopefully with testing tomorrow this will really dial this gun in. I know with the crown job it has potential for accuracy (stacking pellets) but something is floating around, and my groups often shift and move. I'm hoping this will have addressed all flaws except possibly the trigger and the dovetail security as you mentioned.

The picture shows the screws I added on one side of the receiver.

[nervoustrigger]

James, I hope you are getting some trigger time this weekend.  Let me know how your latest mod works out once you've had a chance to shoot some groups.

[stalwart]

Following closely here...

One thing I dislike about these is that they twist easily... feel cheap while being pumped. If you flex it, using the stock and the lever while watching this area, you will see where the weakness is. 3 tiny mig welds turn the channel into box... and make all the difference. A piece of thin sheet metal epoxied or soldered in would do the same. If welding, do not clamp or overweld. The shrinkage from those tiny spots pulled the sides square, and the cylinder fits without slop.

Gives it a whole new feel.

[jmcgall1]

Good idea I hadn't looked too closely at the box construction. If I can get the welder working I'll probably try this and maybe weld more of the shroud, too. The welding ends where the barrel begins to overhang the gun. I really feel close to getting this gun where I want it to be. It seems very accurate but the groups float around. .  A bit. Haven't really had a good day to test but I shot a few yesterday in the rain and at 21yd every two shots would be hole in hole, and then the next two would move slightly and do the same. Polymags bluffed me one day when I shot 2 sub half in 5 shot groups. But have since opened up to about .8in at 20yd. Not bad for $45 gun. I just know I can do better

[jmcgall1]

Hey Jason,

If and when you get the time i would be very interested in seeing the countersunk screws in the dovetail, as i am having trouble visualizing exactly what you are talking about and i do agree that the plastic dovetail could be cause for concern regarding consistency and accuracy.

Have had no luck getting groups to shrink. I don't understand why the gun performs so well some days and not so well others with similar rests and conditions.

last test was June 8  -note, wasn't really planning to post this I was just shooting enough pellets to get a feel for how the gun was throwing them.

Sunny, no wind, humid.
22yd

AA Falcons 7.33gr   6 shots  .981" ctc

Polymags 8gr          7 shots  1.415" ctc      6 shots 1.051"ctc
      Re test             5 shots  .690"             4 shots .480" ctc

JSB Diabolo 8.44gr   10 shot group yesterday in the rain. .700 in
                              7 shots  .813" ctc       6 shots .580" ctc


CPHP  These go from 10 shot groups of .712" CTC one day, to an amazing 7 shot group of 1.3 in

Crosman Pointed      6 shots .792

I was running low on some pellets which is why i only shot enough until i felt like i had a decent representation of that pellet. I shoot benchrested off a shoebox with a rolled dishtowel (very effective actually) and the cross-hairs remain on the center of the .5in bullseye until after the pellet has hit the paper. I shoot between heartbeats and am very confident that I am doing my part.

Some of the groups are reasonable they just float around a little. I'll adjust the scope and they almost never stay on the bullseye. A few will hit. Maybe one or two will go a little right. But in the next group i shoot it will shift, and one or two will go a little left or a little low. I'm fine with a .5in group. But i want it to take the bulls-eye out, and other than the two polymag groups a posted a few weeks back i haven't been able to duplicate those results consistently. Some days it shoots fine, some days things seem to shift around. Next step is to get the welder working and secure everything. The box "spine" of the gun, the shroud, even thinking of welding the shroud to the box and making some  baffles to better secure the inner barrel to the shroud. Also would like to secure the barrel to the receiver better. Noting fancy just think if it is tension fitted it might allow air to escape so some hot glue to seal it off essentially. Then if that doesn't get the results I want, guess I'll just be waiting until i can afford a PCP, or even the new 125 with the vortek (vortex) piston

[AmBraCol]

I've enjoyed reading this thread as the 880 was my first "rifle" years back.  I wore it out, rebuilt it then wore it out again.  It had the smoothbore steel barrel for BB's and pellets.  The receiver was potmetal instead of plastic like current production.  There were probably other differences as well.  We never shot for groups back then, just shot for hits.  That rifle got shot so much I could hit anything I could see within a hundred yards or so.  We took all kinds of small game with them, including iguanas which can be tough customers. 

The smooth barrel depends on the shape of the projectile to stabilize it rather than on spin (which is nonexistent). Still, we experimented to see how to improve them.  A wrap or two of electric tape around the muzzle where it fits into the front sight centered the barrel in there and kept it from rattling around and shifting from shot to shot.  It's been 30 + years so don't recall all the details, but it seems the early 880's had the barrel attached to the valve via a screw holding a clamp and there was a seal between the barrel and the valve.  If they are friction fit now then the system has changed considerably.

A while back I picked up an old 880 in pieces.  It's pretty much unrebuildable so the rifled brass barrel is getting eyed as a possible donor for a ? project somewhere down the line.

Anyway, thanks for the memories.  It's good to see folks playing with the old platform that gave me so many hours of enjoyment way back when.

[Dick Tracey]

I just thought I would mention that Gun Broker currently has two different 880's up for bid now.  Both are listed as having the metal receiver and metal pump arm.  NOTE you will need deep pockets.

DT

[nervoustrigger]

Hey Jason,

If and when you get the time i would be very interested in seeing the countersunk screws in the dovetail, as i am having trouble visualizing exactly what you are talking about and i do agree that the plastic dovetail could be cause for concern regarding consistency and accuracy.

Hi James, here you go.  These little screws button down the freehanging side of the dovetail.  I think I installed 6 screws total; 3 on either side of the loading port.  The most important place is right beneath the scope rings.

A word of advice:  if possible, use steel screws rather than brass.  Just threading into plastic, I wrung the heads off of a couple of brass screws which means I'll have to drill them out if and when I ever decide to pull it apart again.

[jmcgall1]

Very cool Jason, I appreciate you getting back to me on that, and I do believe the receiver is a big problem with the gun's accuracy. I think it's about strung out for all it will give. My last efforts will be towards machining a new receiver cover or fixing the one like you did and welding the box, the line going down the shroud, and the shroud to the box once I can get the welder working. Then it's off to a b-50 or some PCP once the funds are together!