GTA
Airguns by Make and Model => Daisy Airguns => Topic started by: dlee on February 04, 2018, 05:12:46 PM
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Hi all, I picked up a couple of 880s on clearance at the local Walmart right after Christmas (the remaining 880S stock on the shelf was being sold for $25 so I bought 2 of them - now I have 3 total). Decided to sacrifice one to seeing just how far the stock 880 could be pumped.
First let me say that I certainly don't recommend people just randomly overpumping their multipumpers - the stated limit is there for a reason.
Well, I finally did the exp't today, and attached are graphs of the results. The summary is that I didn't get any failures or valve lock or anything like that up to 30 pumps. 30 pumps pushed a CP Wadcutter (7.4gr) at 772 fps (twice in a row, actually). The first graphs is fps vs # Pumps, from 2 to 30. The 2nd graph is a sequence of 11 shots in a row where I pumped 20 times to check the consistency of pellet speed, waiting at least 1 minute between shots and for quite a bit longer between a few of them. I'm amazed at the results - both that the speed kept increasing (albeit with diminishing returns) *and* with the consistency at 20 pumps. The 11th and final shot at 20 pumps was taken after leaving the gun pumped for over 30 minutes while I helped my wife with some things around the house. For $25, that's a consistent 9 fpe plinker (at least until something breaks, I guess). This has certainly got me thinking about what's possible with this gun - wish I had a way to figure out just how much pressure was being stored in the cylinder.
For the record, I used a Caldwell G2 about 1 foot in front of the barrel and shot off a bag.
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It will certainly wear out faster. Other than that, I don't think you should have a problem. Lord knows, i put 20 pumps every pump up i ever had as a kid. They usually lasted decently until i started screwing around with stuff like wd40 to lube it up and lean the barrel with coathangers and tissue paper, lol. Looking back i am surprised any of them lasted as long as they did.
Can you run another couple 20 pumps shots with something in the 10 grain range? I am interested in how that affects the power...
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Good idea. I'll do that. Just ordered a tin of CP Pirahnas (10.5gr) and a tin of H&N Crow Magnums (9.26gr). I only have cheaper pellets right now bc the .177 guns I have are the three 880's and my daughter's pink 760. I'll post back here when the results are in.
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You'll most likely end up breaking the plastic pump arm before anything else.
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I got some CP Piranhas in (10.5gr) and overpumped. Here are the results. Also, I spent some time digging through this forum and of course many people have reported very similar things before. As Bryan mentioned, every kid overpumps these things anyway, so it's not surprising that it's designed to take it. I was just surprised that the speeds were consistent even at 3x the recommended number of pumps - I figured it would be designed to leak and that in turn would lead to inconsistent performance.
Anyway, here are the heavier pellet results as promised. It tops out at around 11 fpe and 685 fps with the 10.5gr Piranhas. And it is consistent, so I've actually re-zeroed the cheap little 3-9x40 scope I bought for it to 35 yards @ 20 pumps. Should make for a great backyard rodent remover and a nice little gun to walk the woods with my daughter and her pink 760.
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How is the accuracy with the CP Piranhas?
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I had my decked out 880 pumping to over 2000 psi shooting 910 fps at 14.7 fpe as I recall
https://www.gatewaytoairguns.org/GTA/index.php?topic=113523.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=113523.0)
check the youtube video in the thread.
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@Rob M - is that gauge reading the pressure in the valve chamber? I'm guessing it has to be since there really isn't much volume left in the tube once the piston is pumped. I asked an engineer at Daisy about the pressure in the valve chamber at 10 pumps and he responded that it is typically in the 700-800 psi range. For the Piranhas, 10 pumps gave me about 600fps and 8.5fpe - if that's 800 psi, then your 900fps and ~15fpe at 2000 psi match up pretty well. I can tell from your previous thread that you've done all this already. Do you think it's possible to get a 12fpe plinker (with 10.5gr Piranhas) at, say, 15 pumps without doing anything except flat-topping the piston and putting in a washer to compress the rubber bumper but leaving everything else stock? That would be great for this backyard usage.
@bhh - I'll shoot a group this weekend and let you know.
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Do you think it's possible to get a 12fpe plinker (with 10.5gr Piranhas) at, say, 15 pumps without doing anything except flat-topping the piston and putting in a washer to compress the rubber bumper but leaving everything else stock?
@bhh - I'll shoot a group this weekend and let you know.
I'm not Rob, but I have an 880 that puts out 12 fpe at 13 pumps.
I made the piston flat-topped, added a washer to reduce the amount of squish in the piston bumper assembly, increased hammer travel, used a nut to add preload to the hammer spring (just get a stiffer spring), drilled the transfer port to .140, reduced probe diameter, reduced the leade in the breech, and ported the transition from the abutment chamber to the main valve chamber.
I've put a couple of tins through it and it's still going strong.
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yes, no fancy machines required. Bruce has done a bunch of mods and actually hit just above my 910 with steel washers and such.. SO it is entirely possible.. YEs the 2000 psi was the valve pressure, No real way to measure the compression chamber pressure , and probably no point other than to experiment with peaks which might translate to efficiency ( who knows.. )
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Rob and Bruce - whoa. I struck a goldmine of knowledge and expertise here. Can I ask some newbie questions? Please pardon my ignorance - I'm still a total newbie to AG in general. I understand the flat top piston and squishing the rubber bumper assembly with a washer. How did you increase hammer travel and what does that do? I think I understand pretensioning the hammer spring to have it snap the valve open more quickly (is that correct?). What is the probe (you reduced the diameter of it)? And does reducing the leade mean putting a taper into it or filling it in? Again, my apologies for asking basic questions like this. I'm learning lots here. I've attached a schematic of the 880 action if it helps. Maybe you could point out the specific locations where things were done? Thanks!
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well your not increasing the travel of the poppet ( the part that seals the valve while pumping ) you are increasing the opening strength and speed.. as for the probe , its the little rod tip that pushes the pellet into its battery position.Its also a partial obstruction to flow, Along with the Transfer port.. that's where the air transfers to the barrel , and resides above the poppet.. Opening this increases the potential flow from the valve to the pellet during firing..I would watch the youtube teardown video , and get very familiar with taking the gun apart and re assembling properly.. then start the mods.
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the gun is a real sleeper when it comes to potential power.. Most people would start with a different gun were they going for 1000 fps in 177 or a 25 conversion , not me .. the blow open valve really makes the sky the limit.. the biggest drawback to this potential is the amount of pumps in order to get to those numbers,. for example , my 910 was on 23 pumps as I recall , with a slight increase in valve volume.. NOW , that being said, I never opened the transfer port or reduced the probe.. Were I to attack it again , I think 910 with 7.9 grains could be done at 17-18 pumps.. especially if a smaller spring was added to the poppet stem creating less back force holding the valve shut .. What you have at 2000 psi is both the spring pressure and the 2000 psi acting on that poppet keeping closed.. since you cannot control the air pressure, you can certainly control the spring pressure.
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I'll try to address each item:
Hammer travel - On mine I was able to increase the amount the poppet opened. See that "shark fin" part of the hammer? Remove material just ahead of that part and then taper the underside of the frame where it hits. Depending on how far you go, you'll likely have to remove material from the top of the shark fin to get it back to the original profile and height. The hammer is soft aluminum so all this can be done with a few swipes of a file.
Hammer spring - Just get a stiffer spring. I added preload to mine using a nut I modified because I didn't want to go to the hardware store.
Barrel leade - Take a pellet and gently push it into the barrel until you feel resistance. At this point it's a nice tight fit. On my rifles it was seated deeply way past the transfer point. The probe doesn't even reach this far, so when the pellet was loaded with the probe, it was just sitting there loosely. Loosely=leaky. So I removed the barrel and removed a little material from the end of the barrel with a file. Now the probe seats the pellet tightly at a point just past the transfer port.
Probe - The magnetic point pulls out if you gently pull and twist. Be careful because it's brittle and easy to crush with your pliers. I replaced it with a finishing nail. Chuck the nail in a drill and use a file to reduce the diameter that sticks out in front of the plastic part. I drilled the hole deeper in the plastic part too.
On one of my rifles I changed one thing at a time a tested it with the chrono after each mod. After the piston fix, no mod made a huge difference, but gaining 5 to 10 fps here and there adds up at the end.
So, pull your 880 apart and start studying how it all works. :D
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brilliant , never even thought of increasing the travel distance of the hammer.. makes sense now since I do it on conventional crosman style valves.
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brilliant , never even thought of increasing the travel distance of the hammer.. makes sense now since I do it on conventional crosman style valves.
Thanks. These things really are amazing in their simplicity and efficiency. I'm trying to decide if I should adapt one to my 1.5" tube pumper project or go with a Crosman style valve.
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Guys - thanks so much. That's an amazing amount of information packed into a few short messages. I understand the hammer travel and probe diameter are all about easier air flow, and the leade reduction is to improve the efficiency of operation (by preventing air from leaking around the pellet). As you say, time to start pulling it apart and seeing how it all goes together. Question on the lead reduction - my barrel isn't threaded into the breech, is that just a friction fit that I can (carefully) pull apart? Thanks again!
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yes the barrel is interference fit , not threaded
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Just heat the outer aluminum housing with a heat gun and the barrel will be easier to remove.
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Thanks yet again (starting to sound like a broken record) - the willingness to share on the forum is fantastic.
Here's the group I promised. 10 shots of the Piranhas at 27.5yds. It's a bit embarrassing (1st group I've ever posted) - just keep in mind that I started shooting AGs late October (3.5 months ago). Also, the gun is completely stock (so even I realize the trigger is tough to manage consistently). Okay, enough excuses - I just need to shut up and practice practice practice.
Relevant info: 27.5yds, 10-shots, 1.125" ctc, 10.5gr Piranhas, avg fpe 10.1 ft-lbs, avg speed 658.4 fps, max/min/es 666/651/15, stdev 4.8 (20 pumps)
At least now I have a solid baseline to start tinkering...
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You're welcome for the help.
It looks like you are off to a good start. That's not bad at all for a stock gun. If that was a starling you would have hit it every time.
Thanks for posting the group. I'm going to have to get some of those to try.
Here's a couple pics you might find helpful:
Probe before and after:
(https://photos.smugmug.com/photos/i-qF8ZPjV/0/d6cee0ec/L/i-qF8ZPjV-L.jpg) (https://www.smugmug.com/gallery/n-Q9N2pc/i-qF8ZPjV/A)
Loading port mod to make it easier to load pellets. Seal off BB port with JB Weld too:
(https://photos.smugmug.com/photos/i-6cn6JQt/0/4d4e8a35/L/i-6cn6JQt-L.jpg) (https://www.smugmug.com/gallery/n-Q9N2pc/i-6cn6JQt/A)
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Here is two other mods to consider. Porting the valve . elongate the slot in the arm that the roll pin rides to move the pistion closer to the valve to tighten up the head space . It works well with the washer on pistion mod.
I did a lot of mods on mine porting valve ,shim the hammers spring, adding travel to hammer, flat top, washer on pistion , elongate slot and Stony kill trigger.i don't have a chrony but it smokes for sure. I get valve lock at 18 to 19 pumps.
BTW the groups you getting ant too bad with crappy trigger and a non dome pellet. a trigger mod will help with that.
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For a $40 plastic gun, with double the max raccommended charge, a soda straw barrel flopping around inside a sleeve, and cheap heavy pellets that are not the least bit aerodynamic- i'll take a group like that straight to the bank. I'd call that good on small game to 27.5 yards. Nice shooting.
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Thanks guys for the encouragement on the shot group.
Definitely intend to do the trigger mod as soon as I get a chance. Also, probably the barrel tape mod and adding some weight to the stock and fore end - those seem to be the most helpful mods for making the gun easier to shoot consistently. That should leave me with a 20-pump 10-fpe plinker. Then with the piston flat-top mod and pre-compression of the rubber spring by adding a metal washer, I think it will be something like a 15-16 pump 10-fpe plinker, which I can totally live with. Or a 20-pump 12-fpe gun. For $40!
Again, thanks for all the expert advice!
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This isn't a very active thread, I realize. I saw someone on YT who put Piledrivers through his 880 and wanted to give it a try just for grins. Here are the results in case anyone else was curious about it:
H&N Piledrivers (21gr):
10 pumps / 457 fps / 9.74 fpe
15/494/11.38
20/517/12.47
25/520/12.61
30.526/12.90
Also, results for the H&N Sniper Mags (15gr):
10/514/8.80
15/5.58/10.37
20/590/11.6
25/590/11.6
Also, thanks again for all the advice earlier - I've done the trigger mod (huge difference in my ability to tighten up groups longer than 30 yards), the barrel tape mod, and added epoxy with lead shot to the stock. I also stuck a Kruger 3-9x32mm scope on it, which also helped with the longer shots (by which I mean 30-40 yds).
Actually in the middle of turning one of the spare 880s into an arrow shooter - there is a neat video about it and I am tweaking that design to allow for a variable valve chamber volume because it looked like the one in the video was exhausting lots of extra CO2 on each shot. Also, I'm using HPA instead of CO2. Have a 26ci paintball tank with the reg output set to 1800 psi (it's a string of about 10-12 bellville washers, so I can always lower the output pressure).
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Anyone just flat out break something overpumping?
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Most often a sweat, ocaisional seals and such.
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Nope, because I don't do it.
As I've said before...
If the gun I have is not up to the task at hand I will go in the house and get one that is. ;)
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Nope, because I don't do it.
As I've said before...
If the gun I have is not up to the task at hand I will go in the house and get one that is. ;)
Some folks don't have an arsenal at their disposal..... :'(
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Nope, because I don't do it.
As I've said before...
If the gun I have is not up to the task at hand I will go in the house and get one that is. ;)
Some folks don't have an arsenal at their disposal..... :'(
Keep over pumping those 880s and they won't have those either. :o
And if you have the funds to upgrade it to withstand the abuse then maybe you have the funds to afford something that was meant to do the job.
But, it's like grandma used to always say... "It's yours, wash it as fast as you want".
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Anyone just flat out break something overpumping?
Never had an airgun as a kid but a few friends had 880s or more often 760s. I always pumped them to 20 or more. Air locked a few of them. I am amazed I had any friends.
Of course now I know it is only air locked and how to fix it, but I don't overpump any of mine. I'm not worried about breaking them but because I have break barrels and pcps I don't like pumpers so much and definitely do not want to spend anymore time pumping them than i have to.
I also have plenty of guns that will put out the power I may need when I need it.
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I've over pumped all of mine to 20 since 1984 with no problems. The brass tube guns will never have an issue with it. The pinned abutment (newer guns) need the abutment pin replaced with a stronger pin. I have moved to tool steel dowel pins. Then they are good to go. I have three 822s, and four 1977s that see 20 pumps all year long. I run through around 1500 pellets a year through those guns and have only had one failure. I had a 822 that cracked a valve body. I am convinced it was a factory defect, as I have two others that have had no issues and built one for my father that gets pumped 20 times every shot with no issues. I also run 1977 piston heads/springs on factory piston links on all of the 822s. I have done the same 1977 piston upgrade on multiple 880s for friends with no issues, all of which are getting over pumped. The 880 with the 1977 piston mod, shooting JSB Beast pellets, at 20 pumps can make 15 FPE. That's illegal in England LOL. So, 15 FPE from an 880 makes it capable of small game past the distance anyone can shoot accurately. They can take the pressure, just on the new guns the abutment pin needs to be upgraded and periodically replaced.
https://www.mcmaster.com/98381A172/ (https://www.mcmaster.com/98381A172/)
https://thedaisybase.com/2023/01/27/pblpowermod/ (https://thedaisybase.com/2023/01/27/pblpowermod/)
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I've over pumped all of mine to 20 since 1984 with no problems. The brass tube guns will never have an issue with it. The pinned abutment (newer guns) need the abutment pin replaced with a stronger pin. I have moved to tool steel dowel pins. Then they are good to go. I have three 822s, and four 1977s that see 20 pumps all year long. I run through around 1500 pellets a year through those guns and have only had one failure. I had a 822 that cracked a valve body. I am convinced it was a factory defect, as I have two others that have had no issues and built one for my father that gets pumped 20 times every shot with no issues. I also run 1977 piston heads/springs on factory piston links on all of the 822s. I have done the same 1977 piston upgrade on multiple 880s for friends with no issues, all of which are getting over pumped. The 880 with the 1977 piston mod, shooting JSB Beast pellets, at 20 pumps can make 15 FPE. That's illegal in England LOL. So, 15 FPE from an 880 makes it capable of small game past the distance anyone can shoot accurately. They can take the pressure, just on the new guns the abutment pin needs to be upgraded and periodically replaced.
https://www.mcmaster.com/98381A172/ (https://www.mcmaster.com/98381A172/)
https://thedaisybase.com/2023/01/27/pblpowermod/ (https://thedaisybase.com/2023/01/27/pblpowermod/)
Your mod is bad*ss.
I have a 922 I rebuilt. What should I do with it to make more power?
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I've over pumped all of mine to 20 since 1984 with no problems. The brass tube guns will never have an issue with it. The pinned abutment (newer guns) need the abutment pin replaced with a stronger pin. I have moved to tool steel dowel pins. Then they are good to go. I have three 822s, and four 1977s that see 20 pumps all year long. I run through around 1500 pellets a year through those guns and have only had one failure. I had a 822 that cracked a valve body. I am convinced it was a factory defect, as I have two others that have had no issues and built one for my father that gets pumped 20 times every shot with no issues. I also run 1977 piston heads/springs on factory piston links on all of the 822s. I have done the same 1977 piston upgrade on multiple 880s for friends with no issues, all of which are getting over pumped. The 880 with the 1977 piston mod, shooting JSB Beast pellets, at 20 pumps can make 15 FPE. That's illegal in England LOL. So, 15 FPE from an 880 makes it capable of small game past the distance anyone can shoot accurately. They can take the pressure, just on the new guns the abutment pin needs to be upgraded and periodically replaced.
https://www.mcmaster.com/98381A172/ (https://www.mcmaster.com/98381A172/)
https://thedaisybase.com/2023/01/27/pblpowermod/ (https://thedaisybase.com/2023/01/27/pblpowermod/)
Your mod is bad*ss.
I have a 922 I rebuilt. What should I do with it to make more power?
That is a brass tube gun, I replace the elastomer with the piston spring from a 1977 on my guns with elastomers but there is not big power mod for those guns. Other than the elastomer to spring swap I just pump them 20 times. Those guns can take it no problem. I would also recommend Ron's trigger mod on the 922. You should expect around 12 FPE at 20 pumps and an 18 grn pellet. If its building less might check the o-rings. If it is an older model with clamp down barrel it will made less power also, they are not as efficient and I suspect leak some around the barrel seal no matter what. With all that being said they are really cool guns and worth keeping even if they aren't the most powerful.