Accurizing the Daisy 880

[nervoustrigger]

Hey guys,

Firstly, this post on accurizing the Daisy 880 is a spinoff of the “Daisy Powerline 880 Pellet choice?” thread at
http://www.gatewaytoairguns.org/GTA/index.php?topic=44364.0

Having been disappointed by the poor accuracy we were seeing from the 880, I spent some time after work this past week out in the shop completely tearing down my son's rifle to rework it. 

Literally took it apart down to every screw, pin, and O-ring.  Deburred and polished up everything that looked like it could use it and turned my attention to the following areas:

Trigger work.  I experimented with improving the horrible 6 pound trigger with a lighter spring.  I had the trigger assembly cycling beautifully in my hand but after reassembling the gun, found that the cam-over action that throws open the valve was too weak.  It would only release a light puff of air and throw the pellet weakly out of the barrel.  I quickly noticed that I could recock it (without pumping) and fire again 3 or 4 times before all the air was expelled.  Well, back in went the craptacular stock spring.

Barrel chop and recrown.  The trigger was disappointing but the main thing I wanted to do though was chop and recrown the barrel.  The factory crown looked pretty bleak.  I removed the barrel from the breech block and cut off about 1".  After doing that, I noticed that the rifling at the factory muzzle was very shallow compared to that of the freshly cut area.  I thought that was a promising sign. 

So I chucked up the barrel in my drill press and set up a fixture to act as a bushing to support the muzzle end where I would be doing the crowning work.  I didn't take a picture of the actual setup but I took one when I touched up the crown on the Crosman 2289 a couple of weeks ago so that's what you'll see in the picture below. 

I started up the drill press and used an emery wheel in the Dremel to square up the end and carefully grind a slight funnel taper toward the bore, then used 320->400-> 600 -> 2000 grit on the head of a #8 brass round-head slotted screw to give it a nice polish.  The picture isn't the best but hopefully it illustrates the point.

Shroud and barrel adjustment screws.  After reassembly, I noticed it was taking an inordinate amount of windage adjustment on the scope to sight it in.  Apparently the little plastic dovetails on the receiver and the barrel are pointing in divergent directions.  So I drilled and tapped 3 adjustment screws into the barrel shroud.  That let me optically center the crosshairs in the scope and just adjust the screws until the POI matched the POA.  This keeps the lateral POI from moving around at different ranges.

Reassembly and sighting in.  After finishing up all my cutting and grinding, I wiped off all the debris and lubricants, then washed and dried the parts.  Lubricated all moving parts during reassembly and got it all buttoned up, then headed out to run some pellets through it to sight it in.  Interestingly, the Gamo Rockets that previously grouped the best were now spraying all over the place.  It looked like the RWS Superdomes were grouping the best so that’s what I sighted it in with. 


The results.  So tonight after dinner my 7 year old son and I headed outside for some target practice.  Turns out that for the sufficiently motivated, a flashlight supplies plenty of light.  For myself, I hung some 1/2” diameter Mardi Gras beads from the target board at 25 yards to blast with the B51.  For him, I set up some spinners at 15 yards and paper at 25.  But he couldn’t resist the idea of the beads and proceeded to hit them 3 out of every 5 shots!  I couldn’t believe it!  I had shot some groups at the same distance one night previous and I couldn’t do that well.  He’s only been shooting since September so maybe I’ve got a natural on my hands.

Overall, the best part was seeing him have fun.

[JPowell490]

That is the most accurate gun, with the most crisp trigger I have ever shot.  You must have bought a lemon.

[blind dog]

Cool write up!
I think it's fun to drive a slow car fast, and make a cheap air rifle perform like a champ.

[nervoustrigger]

That is the most accurate gun, with the most crisp trigger I have ever shot.  You must have bought a lemon.

I'm glad you got a good one.

My wife usually does all the buying of sour fruits.  I went to the store to buy an air rifle, haha . But that was the China lottery I was playing. 

The trigger does have a clean break, it's just so stinkin' stiff until you get to that point.  It's fine for an adult but not so well suited to a 7 year old, that's all.

[drewciferpike]

Turns out that for the sufficiently motivated, a flashlight supplies plenty of light. 

Not to say that the rest wasn't well-written or informative, but that just made my week.

I can't WAIT until my son is old enough to shoot...

[jmcgall1]

Awesome post as I was looking to do the exact same thing to my 880 as well. How does it group now? Any data would be appreciated.

[Sqrl Klr]

Jason that's the % of shots I was getting once I fixed the trigger. I never did any barrel work like you did though. Congrats.

That is the most accurate gun, with the most crisp trigger I have ever shot.  You must have bought a lemon.

I must have bought 5 lemons. A lot of misses with them and issues as well.

That is the most accurate gun, with the most crisp trigger I have ever shot.  You must have bought a lemon.

I'm glad you got a good one.

My wife usually does all the buying of sour fruits.  I went to the store to buy an air rifle, haha . But that was the China lottery I was playing. 

The trigger does have a clean break, it's just so stinkin' stiff until you get to that point.  It's fine for an adult but not so well suited to a 7 year old, that's all.

They weren't fine for me at all. I had to grind it down for a smoother pull since I was pulling a lot of shots because of it.

[nervoustrigger]

Awesome post as I was looking to do the exact same thing to my 880 as well. How does it group now? Any data would be appreciated.

Hi jmcgall, welcome to GTA!

I saw your post in another thread and unfortunately I don't have as wide a pellet selection as you but here is what I'm getting at 25 yards with the pellets I have on hand.  The RWS Super Domes seem capable of 1in groups at this distance but there are fliers.

The results for each pellet is given for 4 shots and for 5 shots.  In some cases it becomes obvious that there are fliers responsible for swelling the group size by 50% or even 100%.  I tend to think the 4 shot measurement is a good indication of a pellet's capabilities but others may view the 5 shot group as a better indication so I'll let you decide.

[jmcgall1]

Yeah airgunwarehouse had a buy 4 get 2 so I went a little pellet crazy. After none of them worked well I setup shop and cut an inch off and recrowned the barrel too. I have only tried the Jsb and polymags, which were stacking pellets at 20yd, so I went out and got a squirrel will do a formal pellet test later

[nervoustrigger]

James, a detail I forgot to include in the spreadsheet is that all shots were made with 5 pumps.  That yields about 530fps muzzle velocity for pellets around 8gr.  I have not done any head-to-head tests to see if there is a meaningful difference in accuracy between 5 and 10 pumps.  I think there shouldn't be, at least at the distances we're talking about, but if you've done any experiments along those lines I'd be interested in hearing about it.

[jmcgall1]

Yeah I was planning on using the best two or three pellets and shooting them side by side while varying up the number of pumps. It's raining today and I have to work the next few days so unfortunately it will have to wait. If you have a chronograph that'd be an awesome thing to check, the velocity curve between pumps, that is.

[jmcgall1]

The method i calculate velocity is by using the ballistic coefficient of the pellets at my alt. temp. pressure. humidity and the ballistic curve the pellets encounter as them move from 5-30 yards. Kinda time consuming and I'm curious to see just how accurate of a method it is.

[nervoustrigger]

I ran a few shots across the chronograph this evening and, with 10 pumps, the 880 is running between 7.5 and 9.0fpe depending on pellet weight.

I also wanted to see what it would do above 10 pumps and it seems to top out around 12 pumps.  My heaviest pellet is the Crosman Premier Ultra Magnum at 10.5gr and it's emerging from the muzzle with a little more than 9.5fpe.

The numbers in the table are averages of relatively small shot counts.  I took just enough shots with each pellet to establish confidence in the reading.  If the first two readings were within 10fps of each other, I stopped there.

With regard to your calculated velocities, in your hunting thread you estimated 640fps with the 8.0gr Polymags and I think you also said all your shooting is with 10 pumps.  Assuming our rifles are similar, I expect they are shooting at around 680fps (a 6% difference).   That translates into the difference between 7.3fpe and 8.2fpe, or 12%.

[aom22]

I've taken some steps to try an improve the accuracy of my two Daisy 880's.
The biggest jump in accuracy occurred with pellet selection, number of compression strokes,
attention to pellet loading technique and careful pumping method.
And, I've had good results ... times two.

Daisy 880: How to Get Better Out-of-the-Box Accuracy
Standing Position
Forearm Fully Supported on Rolled-Up Pad
5-Shots at 20 Yards
6-Strokes of Compression
Unpredictable Wind Gusts


I dropped compression charge by one stroke.
Experimenting with different strokes of compression ... sometimes helps.

Standing Position
Forearm Fully Supported on Rolled-Up Pad
8-Shots at 20 Yards
5-Strokes of Compression
Unpredictable Wind Gusts

[neric]

Really enjoy the posts.  I bought a peach rather than a lemon,,,fantastic accuracy out of the  box.  I was really dismayed with the trigger tho.  JSBs were my best pellet with CPs being a close second.  I plan on polishing my trigger as did Sqrl Klr.  I like the idea of 3 screws in the shroud stabilizing the barrel, but also like the idea of a floating barrel with no shroud; I don't know which would be best

[nervoustrigger]

I like the idea of 3 screws in the shroud stabilizing the barrel, but also like the idea of a floating barrel with no shroud; I don't know which would be best

The barrel shroud is essential in my opinion.  The straw barrel is way too fragile to leave exposed.  Right about the time you get it sighted in, something would bump it and it would be back to the drawing board.

Also in my case there was a staggering amount of compensation needed to put the barrel in line with the dovetails on the receiver (so as to keep the scope near its optical center).  I had to bend the shroud quite a bit as a coarse adjustment and then I used the three screws to fine tune it. 

[jmcgall1]

With regard to your calculated velocities, in your hunting thread you estimated 640fps with the 8.0gr Polymags and I think you also said all your shooting is with 10 pumps.  Assuming our rifles are similar, I expect they are shooting at around 680fps (a 6% difference).   That translates into the difference between 7.3fpe and 8.2fpe, or 12%.
[/quote]

I haven't had a chance yet to sit down at different distances and map out the pellet's flight path. Unfortunatly a relatively expensive experiment with polymags I simply used the muzzle FPE I calculated prior to chop with a different pellet and converted from FPE back to muzzle velocity. The spreadsheet was very useful it's cool to think how the gun actually transfers its energy more effectively to heavier pellets. I would almost expect the forces inside the barrel to be the same regardless of pellet weight, so the resultant muzzle velocity would simply be directly proportional to that force. The heavier pellets maybe spend more time in the barrel, and more pressure is applied over this interval and more force is transfered. force=mass*accel and KE=1/2mv^2   v^2 is the dominate factor yet the heavier mass is enough to overpower the loss of velocity.   The change in mass from 7gr to 10gr increases by a factor 1.4 while the change from of 633 to 743 is an increase by a factor of  only 1.12

There is so much to consider with these airguns. It really never ends.

[nervoustrigger]

Good afternoon guys,

I ordered some Predator Polymags and a JSB sampler from Pyramyd Air earlier this week and they were delivered yesterday.  Given the success James has been having with the Polymags, I was hopeful my son's 880 would shoot them well also.  So naturally I had to get outside today and try them out. 

Setup
I started with a control run using the RWS Superdomes that so far have produced the best groups.  It was a surprise when I measured the group at 0.97", the exact same size as the two previous runs I did a couple of weeks ago!  So that suggests the biggest variable in the test (me) is giving pretty consistent results. 

Very well, on with the testing then.  The JSB sampler consists of 3 domed varieties in 7.3, 8.4, and 10.3gr weights, as well as a "Straton" pointed pellet weighing 8.3gr.  The Predator Polymags are 8.0gr.  As before, each pellet was fired 5 times from 25 yards bench rested, 5 pumps each except for the JSB Heavies (8 pumps). 

Results
Suffice it to say, it looks like these 5 pellets were good choices:

Predator Polymags:  With 5 pumps, the Polymags did not work as well at the RWS Superdomes.  But with 10 pumps, they produced a 0.71" 4-shot group and a 0.92" 5-shot group.

JSB Sampler:  All 3 of the lighter JSB's grouped similarly or better than the RWS Superdomes.  And the JSB Heavies were significantly better, turning in a 0.63" group (ignoring an obvious flier).  Based on that positive result, I shot another group except this time with 12 pumps.  The resulting group was practically identical except the POI was a bit higher and there was no flier.  All 5 shots were a 0.75" group.  They were also going across the chrony at 650fps or 9.7fpe.  Not bad for a $45 air rifle.  Well, a $45 air rifle with about 20 hours of tinkering with it.

Summary
Have a look at the table for a summary.  The new pellets are highlighted in yellow.

[jmcgall1]

Awesome update! Mine holds the JSB's exact at around a one inch and seems to prefer the polymags, CPHP, and rws do well, too. I think the tightest group I have so far was .495 in ctc with the polymags. I haven't noticed a difference with different styles of loading the pellets, suh as shaking the gun and letting them fall into the breech. I did notice a slight poi change when shooting at different temperatures possibly due to the plastics expanding. It's still not as good as I'd like it to be, mainly because my standards are too high. It, however, has gone from the most frustrating gun, to putting 4 squirrels, 2 mourning doves, and one rabbit in the freezer all in under a week. It offers that extra challenge of needing to be extra stealthy in order to successfully deliver a powerful and accurate enough shot at close range. Thanks for the update! Glad to see yours is shooting well!

[lillysdad621]

if your 880 shoots the crosman prems Ultra Mags well you are very lucky. for hunting they are devastating. mine does not group them well... But i can tell you that at 45 yards and 10 pumps they still bury themselves all the way in pass the skirt on a 2x4. great energy retention.