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760 Update...With Chrony Numbers
https://www.airgunforum.ca/forums/topic89537.html
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Author:  MyCrosman [ Sat Sep 18, 2021 4:19 pm ]
Post subject:  760 Update...With Chrony Numbers

Plugged valve hole
lighter valve spring
new custom bolt
1 pump...105fps ////////////////testing with 7 grain Hobby Pellets//////////
2 pump...339fps
3 pump...437fps........stock numbers......263fps
4 pump...486fps
5 pump...533fps........stock numbers.......327fps
6 pump...562fps
7 pump...584fps
8 pump...608fps
9 pump...619fps
10 pump...628 fps......stock numbers........414fps
12 pump...669 fps......stock numbers........430fps
15 pump...695 fps......stock numbers........432fps
Valve did not retain any air at 15 pumps but I won't pump over 15 times since its a plastic receiver... :D

Attachments:
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Author:  Dukemeister [ Sat Sep 18, 2021 4:22 pm ]
Post subject:  Re: 760 Update...

Awesome! That looks like the 7760 aka 760 Classic, good to know.

Author:  Justmyluck [ Sat Sep 18, 2021 8:32 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

Thinking of getting one. Moreso now.

Author:  airmec [ Sun Sep 19, 2021 6:51 am ]
Post subject:  Re: 760 Update...With Chrony Numbers

Very good results! Get yourself an M4-177 rifled barrel and you'll have a pretty fine and accurate backyard small pester.

Author:  lauchlin [ Sun Sep 19, 2021 10:12 am ]
Post subject:  Re: 760 Update...With Chrony Numbers

I have lots of 760 parts if you need any ...........Nice to see some one modifying one .....



I just had a look at what i have there 761 xl and a sears 760

Author:  leadslinger [ Sun Sep 19, 2021 11:38 am ]
Post subject:  Re: 760 Update...With Chrony Numbers

Nice, cannot complain about that. I thought about picking up a metal receiver 760... As I still got a wack of 177 pellets.

Author:  killercrow [ Sun Sep 19, 2021 3:20 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

Do these guns have the smaller front valve half?
I have a Remington airmaster 77 which has this smaller valve. If I were to cut it for a flat top piston I'll also need to cut the check valve too.
Anyway, that 760 could use a flat top piston :wink:

Author:  MyCrosman [ Sun Sep 19, 2021 4:03 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

lauchlin wrote:
I have lots of 760 parts if you need any ...........Nice to see some one modifying one .....



I just had a look at what i have there 761 xl and a sears 760

Thanks...one of the reasons I bought it was to tune it to shoot in the mid 400's with only 3 pumps....which outshoots a stock 1377 with 10 pumps...cant do that with the 1377/22 without an rpal...this makes it a good choice for a basement shooter.... :D

Author:  MyCrosman [ Sun Sep 19, 2021 4:04 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

leadslinger wrote:
Nice, cannot complain about that. I thought about picking up a metal receiver 760... As I still got a wack of 177 pellets.


definitely go for a metal receiver...although I'm having a blast with mine just the same...and welcome back... :D

Author:  MyCrosman [ Sun Sep 19, 2021 4:07 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

killercrow wrote:
Do these guns have the smaller front valve half?
I have a Remington airmaster 77 which has this smaller valve. If I were to cut it for a flat top piston I'll also need to cut the check valve too.
Anyway, that 760 could use a flat top piston :wink:

not sure of the valve difference....760 is setup and shooting great so I dont want to strip it down to check ..flat top....if I had a steel receiver I would do that...

Author:  Petee_c [ Thu Sep 23, 2021 1:08 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

i have a 760 with a rifled barrel from the m4 part that I installed. I also have the bleed hole plugged. I only get 495fps with 10 pumps, but happy shooting in the basement at 6 pumps... which for me is just over 400fps. 35 foot distance I can get about nickel size groups with the RWS Hobby pellets. It doesn't seem to like any other pellets.

unmolested, it was somewhere in the upper 300's for fps at 10 pumps.

I'm thinking about polishing the sear next or decreasing the spring tension on the trigger for better accuracy.

From left to right

Group 1 different gun
Groups 2 and 5 were hobbies in the 760
Group 3 was crosman pointed in the 760
Group 4 was crosman wad cutters in the 760 Image

Author:  MyCrosman [ Thu Sep 23, 2021 5:23 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

Good shooting...I've only used the crosman pointed pellets, Daisy wads and 7 grain hobby wads. For some reason the pointed pellets do not shoot well with a smooth bore but the Hobby and Daisy wads show similiar groups to yours...so thats all I shoot out of this gun now...also a basement shooter at 30+ feet...mid 400's fps is where I shoot indoors also with the 760...

Author:  Phantom Payne [ Sun Oct 03, 2021 10:46 am ]
Post subject:  Re: 760 Update...With Chrony Numbers

Hey "MyCrosman" those are some good numbers, I would be interested in knowing more about the lighter spring and custom bolt that you use - can you share any information on those?

I typically use Crosman "Destroyer" in a smooth bore 760 and can typically hold one inch groups at 25-28yds, which surprised me, that 760 has had only five Copperhaed BBs through it at 5, 7, and 10 pumps soley to measure speeds - I do not intend to use BBs in there in future.

Regarding BBs and bores; on another smooth bore 760 I have tried two and three BBs in a single shot and am impressed with the <5yd pattern, two works better than three, and a 'full power' air charge is needed. Someday will try a siutible wadding around the BBs to minimise leakage. This could be useful during a home/attic invasion of maniacal squirrels representing a 'clear and present danger' of disease and damage. The second BB is dropped down the muzzle in order aquire adhesion to the magnetic bolt/BB --- BEFORE pumping and AFTER charging the first BB ie. charge normally, add second, and possibly thrid, BB down the muzzle, pump with muzzle above horizontal.

Author:  MyCrosman [ Sun Oct 03, 2021 8:56 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

Phantom Payne wrote:
Hey "MyCrosman" those are some good numbers, I would be interested in knowing more about the lighter spring and custom bolt that you use - can you share any information on those?

I typically use Crosman "Destroyer" in a smooth bore 760 and can typically hold one inch groups at 25-28yds, which surprised me, that 760 has had only five Copperhaed BBs through it at 5, 7, and 10 pumps soley to measure speeds - I do not intend to use BBs in there in future.

Regarding BBs and bores; on another smooth bore 760 I have tried two and three BBs in a single shot and am impressed with the <5yd pattern, two works better than three, and a 'full power' air charge is needed. Someday will try a siutible wadding around the BBs to minimise leakage. This could be useful during a home/attic invasion of maniacal squirrels representing a 'clear and present danger' of disease and damage. The second BB is dropped down the muzzle in order aquire adhesion to the magnetic bolt/BB --- BEFORE pumping and AFTER charging the first BB ie. charge normally, add second, and possibly thrid, BB down the muzzle, pump with muzzle above horizontal.


Have you tried the tissue paper on the breech test to check for a leak? Pump it to ten and load a pellet...not a bb and see if the paper blasts off the breech like mine did. I'd be curious to know your results...

Author:  Phantom Payne [ Mon Oct 04, 2021 6:00 pm ]
Post subject:  Re: 760 Update...With Chrony Numbers

I tried it in the past and saw slight movement of the 'kleenex' but nowhere enough to remove it from the gun. I expected that much at minimum since I can see the factory spacing it generous. I bought the gun new several years ago, currently it has <500 pellets through it.

I saw a YT video once by "AM77 Machinist" where he built up the bolt o.d. by sequential layers of 'krazy glue' then filed it down to size, and saw an improvement (older version of 760 I think). When I get the gun back I'm going to look inside to see if adding a o-ring against a stop can possibly work - if I remember correctly the bolt has to pass over/through a space that limits the outside size, and same for the rearward travel (though I don't use BBs in it so can modify any BB related channels).

I'm also going to shim the piston cup (discs of aluminum can ~ .007 in.), and stuff the piston (nails) - I try as much as possible to use or modify whatever the original airgun shipped with since I'm already resource challenged, besides staying less expensive is some of the fun - anyone with money can buy whatever they want and say they 'built' something while having little or no understanding of what is actually providing the improvements.

I'm interested to know details of what *you* did. :)

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