880 vs 1977 piston travel delta?
Select Gate
READ GTA FORUM RULES BEFORE POSTING
GTA Forum Help Desk
GTA Announcement Gate
Dealer Area
GRIP
AirgunWeb Airgun Videos
Airgun Repository of Knowledge
Vendors and Vendor Videos
AirGun Expo 2021
Airgun Expo 2022
Contests and Giveaways!!!
Welcome New Members
In Memoriam
GTA Contributing Members
Shot Show Videos
Hajimoto Productions
Airgun Detectives
Air Gun Gate
BB Guns and Such
"Bob and Lloyds Workshop"
American/U.S. Air Gun Gates
European/Asian Air Gun Gates
PCP/CO2/HPA Air Gun Gates "The Darkside"
Air Archery
Vintage Air Gun Gate
Air Guns And Related Accessories Review Gates
Hunting Gate
Machine Shop Talk & AG Parts Machining
3D printing and files
Buyer's, Seller's & Trader's Comments
Bargain Gate
Back Room
Target Shooting Discussion Gate
Target Match Rules
Shooting Match Gates
Field Target Gates
The Long Range Club
100 Yard Match
Discussions By States
Welcome,
Guest
. Please
login
or
register
.
Did you miss your
activation email
?
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Home
About
Help
Old GTA
Gallery
Search
Stats
Login
Register
Advertise Here
GTA
»
All Springer/NP/PCP Air Gun Discussion General
»
American/U.S. Air Gun Gates
»
Daisy Gate
(Moderators:
GTA-Airgunner
,
Gertrude
) »
880 vs 1977 piston travel delta?
« previous
next »
Print
Pages: [
1
]
2
Go Down
Share This!
Author
Topic: 880 vs 1977 piston travel delta? (Read 1538 times))
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
880 vs 1977 piston travel delta?
«
on:
January 13, 2022, 01:30:39 AM »
Does anyone know the 880 vs 1977 piston travel delta? The 1977 abutment washer looks like it would be fairly easy to remake in different lengths. If you were to put a 1977 valve body in an 880 and lengthen the abutment washer the difference in the sweep delta and put the 1977 piston head on the 880 pump arm you would have a large chamber volume. It would likely take a good many pumps to pressurize but might result in a 22 magnum air rifle lol.
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Ronno6
GTA Senior Contributor
Posts: 5037
yes
Real Name: Ron
Re: 880 vs 1977 piston travel delta?
«
Reply #1 on:
January 15, 2022, 04:38:25 PM »
Check out this thread:
https://www.gatewaytoairguns.org/GTA/index.php?topic=182961.0
Pics of my 1922 are on the later pages....
Seems to me that the 1977 pump frame is about an inch linger, and the pump tube about 7/8", just speaking from memory...
There are many subtle differences inside the 1977.
The valve is the same size externally, but the opening into the chamber is smaller....metal thicker.
The abutment "nose" is stepped down to fit, and one that I plates with, the nose was hollow I assume to increase volume.
The abutment retainer pin was 2 pieces, leaving the middle open.
I don't think the 880 abutment can be shortened enough to accommodate 7/8" of travel, and that would greatly reduce chamber volume.
The bad part about all this is that the unique 1977 parts are not, and probably will not be available from Daisy.
That means that a 1977 has to be cannibalized to make the Frankengun.
It would be easier to open up the leade in a 1977 valve and mod a .22 barrel to fit.
I used a .22 barrel liner from Numrich in mine, but used a valve body from an 822.
The .22 powder burner bore is a tad oversized foe pellets, but I have found one that works well- RWS Meisterkuglen (sp?)
Logged
USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #2 on:
January 17, 2022, 10:32:03 PM »
Thanks for the info. I'm porting an 1977 now. I have enlarged the chamber opening as well. I am drilling the exhaust port to 0.14. Should have it on the chronograph maybe this weekend. I'll post the results.
880 vs 1977 abutment washer
I'm rebuilding a really nice 1976 model 800. It looks almost new. Had to order old style abutment and exhaust, ouch... I'm also rebuilding a 1987 model. They are going back stock. Completely hot riding the 77s though lol. Want to see if I can push a 77 over 20 fpe.
I bought a numrich 22 barrel, 0.305 dia. To do a 22 conversion at some point. The barrel is crooked as a wet noodle. I'm going to straight it with an arrow straightener, cut it, crown it, and choke it. I'm also working on a carbon fiber barrel shroud mod that should add much more protection and rigidity to the barrel. Too many projects and not enough time lol.
«
Last Edit: January 17, 2022, 10:48:11 PM by pblawler
»
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Ronno6
GTA Senior Contributor
Posts: 5037
yes
Real Name: Ron
Re: 880 vs 1977 piston travel delta?
«
Reply #3 on:
January 17, 2022, 10:58:44 PM »
Dunno about hogging out that valve....
Daisy beefed it up to handle the higher pressures seen in the 1977.
Also be careful opening up the transfer port..I know some who have done that had had trouble
getting the exhaust valve to seal.
YMMV
Logged
USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #4 on:
January 17, 2022, 11:19:07 PM »
Yes I kept a watch on the retaining pin sides. I didn't remove enough to make it questionable. I checked the drill against the poppet sealing/mating surface. As long as I keep a steady hand it should be fine. So I'll pop two beers before I start.
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Back_Roads
I Got A 15 Pump BB Gun :) BB Guns Got Much More Complicated :)
GTA Senior Contributor
Posts: 15936
1st Edition Crosman 760 Pump Master
Real Name: James Seiler
Re: 880 vs 1977 piston travel delta?
«
Reply #5 on:
January 18, 2022, 01:50:23 PM »
... cut it, crown it, and choke it. That sounds violent, I will be following
Logged
Wisconsin Collins Hunters Paradise" There's a Sign in Town to Prove It
https://www.zeemaps.com/group=962067
Member Map.
[smg id=6202]
https://www.youtube.com/channel/UC3hMPAjvTtuu7DoNzBZzuKQ?view_as=subscriber
https://youtu.be/PZvrk-L6Gzg?list=PLASJo4rBxMIkewLOlcMHC56YM0BpdR6cb
https://youtu.be/bk_N1l7H2F4?list=PLASJo4rBxMIk6BNY6V_tZahlmptN6qBlk
Ronno6
GTA Senior Contributor
Posts: 5037
yes
Real Name: Ron
Re: 880 vs 1977 piston travel delta?
«
Reply #6 on:
January 18, 2022, 02:04:15 PM »
Quote from: Back_Roads on January 18, 2022, 01:50:23 PM
... cut it, crown it, and choke it. That sounds violent, I will be following
well..............at least it ain't political.................
Logged
USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
Back_Roads
I Got A 15 Pump BB Gun :) BB Guns Got Much More Complicated :)
GTA Senior Contributor
Posts: 15936
1st Edition Crosman 760 Pump Master
Real Name: James Seiler
Re: 880 vs 1977 piston travel delta?
«
Reply #7 on:
January 18, 2022, 02:06:43 PM »
LOL
Logged
Wisconsin Collins Hunters Paradise" There's a Sign in Town to Prove It
https://www.zeemaps.com/group=962067
Member Map.
[smg id=6202]
https://www.youtube.com/channel/UC3hMPAjvTtuu7DoNzBZzuKQ?view_as=subscriber
https://youtu.be/PZvrk-L6Gzg?list=PLASJo4rBxMIkewLOlcMHC56YM0BpdR6cb
https://youtu.be/bk_N1l7H2F4?list=PLASJo4rBxMIk6BNY6V_tZahlmptN6qBlk
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #8 on:
January 19, 2022, 03:20:30 PM »
Was able to assemble a 1977 with the mods show above (ported valve body and drilled transfer port to 0.14", used Viton 90D o-rings in the valve body). I used Ronno's trigger mod. That was my first time installing one so was a little bit of a trick but once I got the right angle on the sear it was not bad at all. The trigger pull is SWEET with the mod. The results are below. The velocities may not seem super impressive but remember this is shooting a JSB Beast pellet weighing in at 16.2 grn so pay attention to the FPE. I'm sure I could easily push a normal weight pellet over 1000 fps.
10 pumps 619 fps 13.78 fpe
11 pumps 650 fps 15.20 fpe
12 pumps 667 fps 16.00 fpe
14 pumps 692 fps 17.22 fpe
16 pumps 712 fps 18.23 fpe
18 pumps 728 fps 19.06 fpe
I believe I can get to 750 fps with a little more work. I started experiencing valve lock at 11 pumps so installed the factory hammer spring on the trigger and left Ronno's mod spring on the sear also. Started experiencing lock at 16 pumps so keep shooting at 15. I also removed material on the bottom of the receiver halfs where the exhaust valve stem sticks down. It is super tight so cut around the stem to make sure it did not contact the receiver. Latter tried 16 again and it worked consistently. Then locked at 17. Same story. Keep shooting until I was able to get to 18 and by that time I was out of time for testing. I think the exhaust poppet and seat need to wear in. That may explain the changing valve lock. Hopefully it will break in and allow me to get to 20 pumps and hit 750 fps. Then I'll have a 20 fpe multipump. I have some stiffer springs coming so after break in i'll swap springs around to find a good trigger pull and no valve lock using Ronno's trigger mod.
Ps Ronno I checked out the 1922. Very nice!
That one is in the que. For me too. I bought a Boyd's blank to do a full length stock for one of my 1977. Figure some day I'll get it cut. I'm modifying a 853 bridge to replace the receiver halves. It is requiring a lot of alterations to the bridge and I'll have to weld mounting plates to the frame. Going for an all metal 1977 with carbon barrel shroud and threaded sleeve on the end of the barrel for an ldc. Thinking Donny FL sumo.
«
Last Edit: January 19, 2022, 04:14:08 PM by pblawler
»
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Back_Roads
I Got A 15 Pump BB Gun :) BB Guns Got Much More Complicated :)
GTA Senior Contributor
Posts: 15936
1st Edition Crosman 760 Pump Master
Real Name: James Seiler
Re: 880 vs 1977 piston travel delta?
«
Reply #9 on:
January 20, 2022, 08:41:08 PM »
Yup them 1977's can get some lead moving, just as well as a PCP with a little TLC
Logged
Wisconsin Collins Hunters Paradise" There's a Sign in Town to Prove It
https://www.zeemaps.com/group=962067
Member Map.
[smg id=6202]
https://www.youtube.com/channel/UC3hMPAjvTtuu7DoNzBZzuKQ?view_as=subscriber
https://youtu.be/PZvrk-L6Gzg?list=PLASJo4rBxMIkewLOlcMHC56YM0BpdR6cb
https://youtu.be/bk_N1l7H2F4?list=PLASJo4rBxMIk6BNY6V_tZahlmptN6qBlk
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #10 on:
January 24, 2022, 01:17:02 AM »
New springs came in but they were a bust, they were too long. I tried cutting them down but that didn't work well. Assembly was very hairy. Free length needs to be between 0.75 to 0.785. So back to the stock room. I ordered more springs between 0.75 and 0.785 in rates from 14.5lb to 25lb. Hopefully one of those will get the 1977 to 750+ fps with the JSB Beast pellets. If so that will make the 1977 a 20+ FPE air rifle for less than $100 investment. The mods to the 1977 can be seen above. I am over pumping using viton seals. I have been over pumping my other 1977 rebuilt with buna o-rings (20 pumps). It has been working reliably and holding seal for 6 months. When hunting it has not problem holding pressure for hours even in below freezing temperatures. I have the option to use powder guns but something hit me about a year ago and my childhood 881 memories of hunting squirrels made me want to go back to air rifles. Now I am wanting to deer hunt with one too! I see a 50 cal in my future lol, but for now I want to build a few custom 1977s and restore some child hood 880s.
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #11 on:
January 24, 2022, 08:36:56 PM »
Well while I am waiting on new hammer springs for testing, I removed the valve body and inspected the abutment washer retaining pin to see if it was holding up to the additional pressure. It was slightly bent, sooo. I am going to replace it with oil hardened drill rod and see if that can take the pressure better. Any thoughts?
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Ronno6
GTA Senior Contributor
Posts: 5037
yes
Real Name: Ron
Re: 880 vs 1977 piston travel delta?
«
Reply #12 on:
January 24, 2022, 08:50:11 PM »
Some 1977s have a split pin rather than 1 solid one, leaving the middle open.
I believe those had a tubular rather than solid nose on the abutment.
But, the valve walls are originally thick in that area.....
Maybe yours bent due to high pressures??
Going to a stronger pin may reveal the next weakest link.....
Logged
USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #13 on:
January 26, 2022, 12:00:32 AM »
Made up the drill rod abutment washer retaining pins. I ported another 1977 I am putting a carbon fiber shroud on and drilled the transfer port to 0.14". As you were referring to Rono, when I pressure tested it I heard it hissing and not building pressure. I removed and reinstalled the poppet a couple times with no success. After inspection I messed up the angle with the drill bit and removed too much of the fillet on the barrel side of the port hole. To fix it I used a case flash whole trimmer and chamfered the port hole. After reassembly it sealed fine and held pressure good. Soo, if anyone drills out the transfer port and has sealing issues you might try chamfering the port hole with a case flash hole chamfer tool. It worked well for me. I used Lyman Flash Hole Uniformer - 7777760.
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #14 on:
February 21, 2022, 11:07:36 PM »
The new, new springs came in finally, but.....there are still issues. I tried to double spring Ron's mod (i.e. the Mod spring and a larger spring over the provided spring. It was SUPER stiff. I almost never got the shear installed fighting the springs. My thumb is still numb hours later. I was excited to test it. I figured there was no way I would experience valve lock and have a light trigger. That didn't happen. The trigger pull was good but it was a pain to cock, and I still experienced valve lock earlier than using the mod and factory spring. Soooo, I am going to design a piece to remove the spring from the trigger but maintain a rear spring and use an extension spring attached to the safety arm of the trigger and sear for a trigger return. I'm thinking a tube with a slot at the top the sear travels in and a hole at the bottom for a retaining pin. Drill the valve body near the bottom below the sear spring seat, use a factory sear pivot pin to retain the tube with a second mod spring or a shortened factory spring. I'll post a model soon. The rear spring adds a lot of force as it has a long lever arm. Using Ron's mod and a strong rear spring should allow running high pressures without valve lock and still have a nice trigger.
This is my idea for a spring retainer to get the rear spring off the trigger. Again will drill the valve body for a pin (same factory pin used for the sear) to hold the retainer and for the bottom of the spring to rest on.
«
Last Edit: February 21, 2022, 11:59:44 PM by pblawler
»
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Ronno6
GTA Senior Contributor
Posts: 5037
yes
Real Name: Ron
Re: 880 vs 1977 piston travel delta?
«
Reply #15 on:
February 22, 2022, 12:03:54 AM »
I am of the opinion that most valve lock problems are due to a stiffer spring inside the exhaust valve from Daisy.
Metal sided 880s work fine using the original sear spring in the front location, but not newer ones and 1977s...
I have tested some 1977s to 15 pumps with no valve lock problems, while others start the problem at 7 or 8 pumps......
I have seen very few lock problems with my current setup, however........
I had contemplated a dual spring setup as what you are doing, but I did not want to have installers have to do any drilling or other marching to their valves to install....
I would be interested to see if your original spring in the original location resulted in valve lock....
«
Last Edit: February 22, 2022, 12:24:45 AM by Ronno6
»
Logged
USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #16 on:
February 22, 2022, 12:37:55 AM »
Your mod works great in my 880s and the 1977s until I start over pumping. I have not noticed valve lock with the mod that I also didn't experience with the factory setup. The mod I'm trying to design is more intrusive for sure. It's a bit more than just assembly. It will require drilling the valve body and for plastic stocks probably removing some material from the inside of the plastic "Forks". I'm trying to hit 20 FPE or more with the 1977 so over pressuring/pumping is causing valve lock with the factory setup. Using your mod in conjunction with the factory spring is working pretty well but trigger pull is very heavy. Getting the factory spring back off the trigger but still on the shear should allow for over pumping the 1977 and have a good trigger. I've go to just over 19 FPE before valve lock with no seal issues. The abutment pin bent but since I have replaced it with drill rod so if I can ekk out 30 more fps I will be over 20 fpe. The JSB 16 grn pellets at 20 fpe are plenty of penetration for raccoons and can stretch shots out to as far as my skill will allow. I'm hoping the carbon fiber shroud will tighten the groups up so off the bench I can shrink the groups to under an inch at 50 yards. The barrel is tight in the CF shroud that is doweled and screwed to the frame. That should do more for accuracy than the popular tape mod. One day I'll get these mods all done and can test again LOL.
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #17 on:
February 24, 2022, 10:02:24 PM »
I built a double spring trigger mod using Ron's trigger mod and adding a second mod for the rear spring. I used 13/32 thin wall aluminum tubing for the spring retainer, a shear pin, and a aftermarket spring. I put the frame in CAD and added an additional hole 15mm behind the trigger pin hole. To locate it I printed the frame drawing to scale and located it to the frame. This gave multiple points to locate from, pin holes, frame edges, etc... I then punched the center of the new hole and drilled it 0.123". I drilled through the frame and valvebody in one operation. The spring retainer was easily formed with a file. The thin aluminum works fast. I had to cut a coil and a half from the spring. The compressed height needs to be 5mm. I printed an installation tool and installed the spring and retainer. I ordered a expansion spring to install on the trigger safetly lever and shear to return the trigger when cocking but it has not arrived yet. The trigger spring seat must be removed. I also filed the trigger shear and installed the trigger. The result is sweet. It hits the poppet hard and the trigger pull is amazing. It is extremely light and the file work removed all creep. The lever where the spring seat was stops at the new retaining pin so there is no over travel. This trigger is comparable to my savage accutrigger on my 17 hmr. The only trigger I would say is better is the ELF trigger on my AR10. Having a trigger this nice on a 1977 or 800 with the strength to handle high pressure is exactly what I was trying to achieve. Hopefully it will help me hit 20 fpe with the 1977 while also tightening the groups.
https://www.mcmaster.com/7237K36/?SrchEntryWebPart_InpBox=91125a445
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Ronno6
GTA Senior Contributor
Posts: 5037
yes
Real Name: Ron
Re: 880 vs 1977 piston travel delta?
«
Reply #18 on:
February 24, 2022, 10:33:41 PM »
That's some nice work!
Logged
USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
pblawler
Squirrel and Rabbit
Sharp Shooter
Posts: 632
Know where I hit'em by the sound of the whaap!
Real Name: Patrick
Re: 880 vs 1977 piston travel delta?
«
Reply #19 on:
March 04, 2022, 12:28:21 PM »
So I figured out the best return spring option if using the rear spring mod. It is an expansion spring connected to the rear spring seat pin and the trigger sear arm. Anyone wanting to do this does it at their own risk, modifying a gun can be dangerous and possibly kill you....... So I drilled a 1.85mm hole in the trigger sear arm. There is a round boss about half way up the arm. I drilled the hole in the center of that boss. Given the small amount of pressure that arm is under I believe there is no way that small of a hole will ever be a problem. With the mod it is under way less than 4 lbs of torsion and the tension is not going to be an issue. After installing the return spring the trigger does rest when the sear/sharkfin is depressed but it is not as snappy as the factory setup because it is ounces pulling it verses pounds pushing it back. The springs come with the ends closed so the open end of the end loop must be bent/pulled out of the coil so that it can hook around the spring seat pin and sear post. I am anxious to test it with both front and rear hammer springs. It snaps hard when fired and has right around a 2lb trigger pull. Lock time should go way down, poppet clearance maxed and pressure capability much higher.
Logged
USA, AL, Falkville
Welcome to
thedaisybase.com
Print
Pages: [
1
]
2
Go Up
« previous
next »
GTA
»
All Springer/NP/PCP Air Gun Discussion General
»
American/U.S. Air Gun Gates
»
Daisy Gate
(Moderators:
GTA-Airgunner
,
Gertrude
) »
880 vs 1977 piston travel delta?