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All Springer/NP/PCP Air Gun Discussion General => American/U.S. Air Gun Gates => Crosman-Benjamin Air Gun Gate => Topic started by: threesuns on November 20, 2022, 07:50:41 PM
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I like my vintage MSPs but don’t have any in .177 cal. Never thought much of the 760 till I resealed one for a coworker & figured I start reading & just casually looking
Well I found 1. An oldie in great condition & getting it ready for a reseal, look where I found the date code!
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Nice furniture on that one for sure 8) I put mine together from a box of parts, it sports a flat top piston and valve. Crony is with a AA 10.3 gr pellet.
(https://www.gatewaytoairguns.org/GTA/MGalleryItem.php?id=6202)
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Did I read somewhere that the quad seal can be replace with an oring?
If so anyone know what size that would be?
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Did I read somewhere that the quad seal can be replace with an oring?
If so anyone know what size that would be?
Nice first variant you got there, from 1966 if I see well?
I've used a metric Oring 4 x 8 x 2 mm WITH NO FAILURE into my Cr140. Just make sure to thoroughly clean the groove and rear ''nipple'' of the valve, and use liberal amounts of silicone oil or grease ;).
Got the idea here: https://anotherairgunblog.blogspot.com/2010/02/some-more-notes-on-reassembling-crosman.html
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“ Oring 4 x 8 x 2 mm WITH NO FAILURE “
happymecanic, thank you for the xtra proof that it will work. I’ve avoided the “blow off valves” since my 1400 years ago. The ergonomics of that rifle just seemed right BUT NY requires 600fps to hunt with an airgun & to get there, the trigger became the difficult part.
I don’t hunt as much now & shoot mostly for therapy, I mean fun. This 760 from May ‘66 (56) was just too purty to pass up.
I don’t think I’ll molest this one & keep it original. Even shooting BB’s. Gonna go look at another older 760 & hope this one has the 13xx type valve.
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You're most welcome Timothy.
If you want a manual cocking 760 with the 13xx-like valve, look for the 5th variant (1977-80) and later. They shall have a serial number, and you may even find one with a rifled barrel.
Tim at MAC1 airguns has a flat-top Oringed piston head ( and complete seal kits) for these self-cockers 1st variant: https://www.mac1airgunshop.com/product-p/cr760rk.htm (https://www.mac1airgunshop.com/product-p/cr760rk.htm)
Generic seal kits can be found easily at many places, but I prefered to use a flat-top piston head when I re-sealed my 140. I just remembered I also re-sealed my converted-to-.22 2nd var. 760 using the metric Oring, and I get velocities in the high 400s with very consistent fps, the metric Oring indeed works well.
BTW here's the link to the Crosman product dates of manufacture page: https://discover.crosman.com/blog/crosman-product-dates-of-manufacture (https://discover.crosman.com/blog/crosman-product-dates-of-manufacture)
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Had to do a little more research after struggling to remove the brass ring on the pump rod without buggering everything up. The one I did a few weeks back came apart easy … but thanks to GTA search tool I found a solution ( https://www.gatewaytoairguns.org/GTA/index.php?topic=149477.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=149477.0) )
Rummage around to find just the right washer, get out the demel & voilà.
Gotta be sure to put it somewhere I won’t forget, next time I need it.
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Very nice early example you've got there.
I can't see the number, but it sure looks like a very early 1966 example.
Dark grey receiver, brass plated trigger, square stock tang / receiver slot.
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I have to learn those xtra little ID indicators. Other than the tootsie roll pump grip, until I found the “56” on the stock tang, I only new it was an oldie. I pinned the Crosman dates of manufacture page but its pretty vague.
Which begs another question … happymecanic says I should look for a ‘77-80 variant. Other than being the 1rst “manual cocking” 760, what makes it better than a mid 80’s edition?
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Which begs another question … happymecanic says I should look for a ‘77-80 variant. Other than being the 1rst “manual cocking” 760, what makes it better than a mid 80’s edition?
I said 77-80 and later variants, not just specifically the 5th one ;). I have a 6th and an 8th variant that have factory rifled barrels, I find them more desirable than my 5th variant with a smooth bore barrel. The 6th variant does have the metal receiver AND the rifled barrel, which makes it the most desirable 760 in my collection IMO. In '83 (7th variant) they switched to the plastic receiver.
Cheers!
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Nice furniture on that one for sure 8) I put mine together from a box of parts, it sports a flat top piston and valve. Crony is with a AA 10.3 gr pellet.
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I had no idea they could make that kind of power. How many pumps did it take to hit 640 with 10.3s?
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Nice furniture on that one for sure 8) I put mine together from a box of parts, it sports a flat top piston and valve. Crony is with a AA 10.3 gr pellet.
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I had no idea they could make that kind of power. How many pumps did it take to hit 640 with 10.3s?
That is the full 10 pumps, little bugger cracks like a rifle ;)
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Just found this & thought, just like my ‘66, all metal & wood with tootsie role pump but stamped “10”
( https://www.ebay.com/itm/RARE-Vintage-Crosman-760-Powermaster-Air-Rifle-1960s-For-Parts-Repair/195493145599?hash=item2d844cabff:g:lSEAAOSwuixjgsof&pageci=85325bb9-a380-49c6-89d8-de8e035de654&redirect=mobile (https://www.ebay.com/itm/RARE-Vintage-Crosman-760-Powermaster-Air-Rifle-1960s-For-Parts-Repair/195493145599?hash=item2d844cabff:g:lSEAAOSwuixjgsof&pageci=85325bb9-a380-49c6-89d8-de8e035de654&redirect=mobile) )
now I see the differences just with the 1rst variant
1966 - square stock tang vs no tang
- tear drop bolt knob vs acorn nut
- brass trigger vs blued steel
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Had to get a “Honey Do” project done after Thanksgiving and have finally reassemble my ‘66 760. As said, kept it all original right down to the puff off air in my eye with every shot.
Question for those more experienced … I m getting good consistency 3-7 pumps & can keep all BB’s within 1-1/2 inches at 30’ … BUT 8, 9, or 10 pumps while velocity increases (some) it is all over the place & throws accuracy out the window … not that I need to pump more but is this normal? do I just need to break it in? or just call it 6 pumps is the max?
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That is par for the course for BBs, Daisy may be more accurate but at the lower pump levels. Some have had good luck with copper coated lead BBs also.
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Just received a manual cocking 760, dried up, worn out & neglected … so got it cheap.
I’ve had the daisy LW barrel & front globe site just waiting for a home & think it can be made to fit.
I’ve read about the 760 / 66 mods & its peaked my interest.
But since the 362 is now out, I wonder if more could be had by fitting a 362 comp tube?
Is crosman supplying parts for the 362 yet?
What about stock options, especially the pump arm handle?
Any input or thoughts are welcome?
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Crosman came through & my 362 tube arrived today. I’ll have to think more about how to make it work with the 760 though.
For comparison, pic of my ‘78 bolt cocking 760 project, a 66 tube (easy enough its been done before), the 362 tube & a 1377.
If I don’t make a 762 … maybe a .25 MSP is in my future
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Made a little headway on my 1978 760 project.
Lothar Walther barrel is fitted up. The step on the beech end was sized perfectly! It was just a tad long, needed a port hole and some chamber work.
Have been reading up on some of Bob Sterne’s past work and decided NOT to change the barrel port size, but to drill it inclined about 10* towards the muzzle. After placing the barrel in my drill vise, I used a carpenter’s square to guestimate the 10* before drilling.
I will rework the valve similarly, to try to get the smoothest exhaust flow possible and think I may have a way to incorporate a retractable bolt since it only has to come back the diameter of the barrel port or a little less. So 1/8 inch max!
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Still thinking about a retractable bolt. However there’s a chance I could ruin a part NLA from crosman, so figured the K I S S principle might apply. Lots of good ideas for bolt mods found researching here.
Since the 760 bolt is a non rotating straight push bolt … here’s what I came up with to start. Not a probe and not hollow either but it should breathe easy.
Starting with a 5/32 K&S brass tube (its what I had in hand) opened it up to 1/8 inch to fit the step in the plastic bolt and then reduced the nose to fit my LW barrel. Trimmed to fit.
The bolt just fits and does not fall out of the breech on its own. Figuring this should negate any additional sealing like an O-ring. Time will tell.
Cut the notch to match the barrel port with my dremel.
Yes the magnet is still in there and with the angled barrel port, it is rite at the back end of the hole.
Assembled to test and it seated a 10.5 CPUM with only slight resistance, a bit more with 10g H&Ns and JSB.
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Gonna have to buy time to tackle my biggest hurdle … valve mods.
I m getting an itch and have settled on using the 66 tube. It will drop rite in and give just that little bit xtra over stock.
First to quote from rsterne 10+ years ago
“rule number one of "pump and dump" style pumpers (where all the air is realeased every shot):
When you don't want to pump much, use a small valve.... When you want maximum power, volume will help, but more pumps will be necessary.”
So I’d like some input and here are some components I have on hand
New poppets modified and not
Check valves: current (has the pin. needs to be longer but was a dry run to make sure I could do it) old style, or vintage with 2 different aluminum volume reducers
Springs
Is pump 1x and shoot even doable? With 10x doing 2 shots?
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Thinking about how to rework my valve found next to nothing about the elephant in the air flow, THE THROAT, unless going 25 cal +. I looked at my xtra valves 13xx, 2240, and discovery they ALL have the same throat design and size. A flat bottom with an exhaust hole in the side and NOT rite on the flat bottom. That cannot be good for airflow.
My 760’s valve is brass and I have a heat source, a spool of solid core silver solder and some flux. 2 coils wrapped around a small drill bit filled the throat just about 1/2. I concentrated my heat where I wanted the solder to flow, so about 2/3’s around the valve opposite the exhaust port.
The result was better that expected, except maybe 1/2 coil more solder woulda been just rite. But no solder in exhaust port and the stem hole just needed to be cleaned up where it enters the throat. Next I used the small ball bit and my dremil to shape the throat for flow towards the exhaust. No more flat bottom just a smooth radius to the back edge of the exhaust, which I then angled towards the seat opening.
I still have to add a retention screw which I’ll locate 180* from the exhaust port. It won’t interfere with anything there.
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Nice to see some love for the 760.
Got a 1977 first variant for Christmas back then and still have that gun.
Since then have acquired and modded several 760/pumpers.
Longer pump tubes, converted one to 22 cal, even made two into PCPs including an 86 plastic fantastic.
The V5 is my favorite but they're all good with a little work.
Here's some links to give you some ideas:
https://www.gatewaytoairguns.org/GTA/index.php?topic=135148.msg1360848#msg1360848 (https://www.gatewaytoairguns.org/GTA/index.php?topic=135148.msg1360848#msg1360848)
https://www.gatewaytoairguns.org/GTA/index.php?topic=153447.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=153447.0)
https://www.gatewaytoairguns.org/GTA/index.php?topic=183883.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=183883.0)
https://www.gatewaytoairguns.org/GTA/index.php?topic=153586.msg155690414#msg155690414 (https://www.gatewaytoairguns.org/GTA/index.php?topic=153586.msg155690414#msg155690414)
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Refined the valve nose to better fit the piston cup.
Tack Driver 10 thanks for the links. I used a spent 223 case to align the valve exhaust with the corresponding hole in the compression tube when setting up for the retention screw. It fit so well I cut it off and fit it to the breech block.
Not sure if my modded valve will benefit a MSP so much but I could see it maybe adding some additional efficiency in other applications.
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Having secured the valve with a retention screw located by exhaust alignment its time to pick a piston. Original 760 is steel but short. The 66 is a wee bit longer but soft plastic. This is the one guys were stuffing to get a bit of xtra performance out of their pumpers. Finally the new 13xx pistol is the longest, still plastic but semi rigid.
I made up a cup shim incase I need it. Anyone unfamiliar with the cup shim just know its actually 2 pieces. The shim just smaller than your cup and a 2nd piece, a solid disc that goes under the cup inside the piston. I’ll cut mine from a plastic water bottle if needed.
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i decided on the initial valve internals … reprofiled poppet and modified stem with the vintage check valve (pinned to reduce headspace) and the small aluminum spacer. It’ll be middle of the road for valve volume.
A lot of good it’ll do to have an accurate LW barrel if nothing aligns & the trigger is atrocious.
Tach Driver 10s links have some good ideas like epoxy in the clam shells. I m going with shrink tubing on the barrel initially. Trigger spring mods won’t be an issue, but I have to think about the seer engagement and 1rst stage take up. I m not a machinist and just have a drill press and small HF wood lathe. So precision mods to any components are out.
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Polished the hammer last nite, flattened the spring seat (not sure this was really necessary but in-conjunction with a top hat should minimize potential for coil bind) and added shrink tubing to minimize seer engagement.
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760 update … good news first - it held air overnite
But I have more work to do - My modded probe is better but still leaks at 8-10 pumps
Pumping is too easy IMO - Still headspace issue ??
It’s got a pretty good crack so I know I m waisting air
First stage trigger is too long. Stage 2 is not target short but smooth
Bolt is pretty sloppy. I don’t like it!
Now I remember my biggest dislike of my old 2200. Like finger nails on a chalk board, the sound of the plastic pump arm closing on the pump tube each compression stroke!
More refinements to come.
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Best mod for less than $10! I didn’t expect the epoxy to expand as much as it did and could have used less in the stock and added more to the pump arm. Even so I have enough now to add a rubber strip to cut down on the hollow plastic clap when pumping.
Stock also feels sooooooo much more solid!
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I have videos on my YouTube channel. Just look for unionrdr channel & search videos. They have several parts for each one & are full restorations. Including variants 1 & 2. Powemaster's and Pumpmaster's as well. Al about seals, valves, bluing/staining etc.
(https://imagizer.imageshack.com/v2/640x480q90/922/NVKI3M.jpg) (https://imageshack.com/i/pmNVKI3Mj)
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unionrdr - that is a lot of 760’s! Haven’t decided on addressing cosmetics yet. But I’ll check out your videos.
I m hoping to wrap this one up soon and have reworked the trigger springs and added a brass barrel for 1rst stage trigger take up.
That then required removal of some material from the interlock, which kept trigger from being pulled while the bolt was open, but now allows me to un-cock the rifle if needed.
Litely coated the bolt with silicone grease before filling the carrier void with JB Weld. After it started to set, I trimmed the excess with a razor knife and gently started rotating the bolt till it broke free.
I removed the shrink tube from the barrel and added shims to the barrel supports in the clam shells. Makes it easier to get everything aligned for reassembly while still giving xtra barrel rigidity.
Time to address the bolt sealing issue.
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Worked on sealing up the bolt probe today. Created an O-ring groove between the barrel and barrel support.
Added another .010 shim between the valve halves to take up a bit more headspace. Also replaced the small aluminum spacer with the larger spacer further reducing volume.
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Here it is. At 5lbs 4oz, I have an accurate 7.5 ftlb max .177 MSP with 10.5g pellets.
It is super quiet at 7 pumps 510fps. I can shoot in the basement without irritating my wife as she watches tv or facetimes with her sister.
At 8 pumps with 7.9g pellets I m at 615fps but there is a notable crack as the pellets leaves the muzzle. I suspect its just more efficient use of air with the heavier pellets.
It will dump all the air at 12 pumps with a significant change in POI. But at 30ft in my basement 7.9g at 5 pumps or 10.5g at 7 pumps, both just over 500fps, are real close in POI.
Those are .25 inch bullseyes on my home brewed test target.
My main goals here were quiet (efficient MSP without resorting to adding an additional moderator)
accurate (LW barrel) because as Toby Keith said “I m not as good as I once was”
Minimum power was factory fps - exceeded :- )
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What's my 1969/1970 Crosman 760 worth. I got it when I was a kid. I also have one from around 1995 that was my son's.
They are sitting in the attic in a case and probably better for someone interested in them to have.
Dave
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Hard to say. Condition means a lot. 1966-70 was the 1rst variant but there are subtle difference even during those years of manufacturer.
FWIW my 1rst variant that started this thread set me back $25 and needed to be resealed, which I was able to do myself. The 1978, 5th variant, that I just wrapped up … if I was looking to buy, just the front and rear target sites NEW, would cost more than I have into it.
The experience though has been priceless.
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Blue Book says for a 760 30-15 from 100 % condition, to 60 % First variant add 300%
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Update on my ‘78 760 custom target … I don’t know what coating Daisy put on that 888 LW barrel that I used but, It Is Awesome! Its like a satin plastic coat material. Carrying this thing up and down the basement steps by the barrel/muzzle weight/site is of no consequence.
I found some old 16.1g Eujins, at 12 pumps they were super accurate, and POI was just on the high side of my 1/4 bullseye targets at 30ft. Energy bump was slight at 7.8ft lbs. I don’t have many so the 10g heavies will be the go to pellet.
Finally a beautiful start to the day, most unusual for mid February, bright sun, calm winds and 40*F … I had to see how this gem performed at distance. My AirArms rat is at 15 yards with a 3/4 bull, my Crosman 1-1/4” spinners are at 25 and the squirrel reset target is at 35. I started close and figured 8 pumps would work at 15, no changes to sites or hold and I went 3 for 3 killing the rat. I had to try the spinners at 25. Powered up 12 strokes of the pump lever, loaded a pellet, settled into position, safety off, and as soon as the breeze let up, the spinner went round and round. I was having so much fun at 15 and 25 yards, I never even tried the squirrel.
I m confident I could hand this to any non airgunner and make them smile. Its lite, but not too lite, easy to operate, and accurate.
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i decided on the initial valve internals … reprofiled poppet and modified stem with the vintage check valve (pinned to reduce headspace) and the small aluminum spacer. It’ll be middle of the road for valve volume.
A lot of good it’ll do to have an accurate LW barrel if nothing aligns & the trigger is atrocious.
Tach Driver 10s links have some good ideas like epoxy in the clam shells. I m going with shrink tubing on the barrel initially. Trigger spring mods won’t be an issue, but I have to think about the seer engagement and 1rst stage take up. I m not a machinist and just have a drill press and small HF wood lathe. So precision mods to any components are out.
Ive recently also picked up a 5th variant which looks like the case with this one too. The one i got comes with the metal barrel band (the transition to plastic band seems to be between year 77 and 79?). Might leave it as a smoothbore bb shooter for close range plinking if I can get the premium or match grade shot to group well.
Side note: the earlier variants seem to have had a screw holding the barrel and tube together, not sure if that resulted in higher accuracy or not though.
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Tweaker enjoy your 760. I was surprised with the accuracy of my 1rst variant 760, using BBs and I kept that bone stock.
Details are sometimes vague but https://discover.crosman.com/blog/crosman-product-dates-of-manufacture will give some info on the variants.
“Side note: the earlier variants seem to have had a screw holding the barrel and tube together, not sure if that resulted in higher accuracy or not though.” [/quote]
If your referring to the bolt on the left side of the receiver, same side as the BB reservoir loading, variants 1 - 4 … that secures the valve, in the auto cocking design. Since the sites are attached directly to the barrel, not sure it would effect accuracy too much.
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reread “Side note: the earlier variants seem to have had a screw holding the barrel and tube together, not sure if that resulted in higher accuracy or not though.” [/quote]
variants 1 - 4 did have a (breech) screw securing the barrel to the tube. Some were rifle barrels. If not I don’t imagine one could be made to fit easily.
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Tweaker enjoy your 760. I was surprised with the accuracy of my 1rst variant 760, using BBs and I kept that bone stock.
Details are sometimes vague but https://discover.crosman.com/blog/crosman-product-dates-of-manufacture will give some info on the variants.
Thanks Tim I hope to do a rebuild on it soon just to make sure everything is in order inside. Also that was a nice job what you did with the 66 pump tube , i didnt realize it was a drop in replacement. Wonder if the 2100 tube is also a drop in? A lot of potential modifications.
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Found this locally and snagged it for 10 bucks. A 6th variant with a rifled barrel! Figures I would find another project just as I m ready to start back at the the golf course after my winter break.
Anyone know if this is any more rare with the rifled barrel? How much better is the factory rifled barrel going to be with pellets? I can hear BBs rattling around inside maybe that has degraded the rifling some.
Should I keep it all original? or incorporate some of the mods from my 5th variant?
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The ones with the rifled barrels are a tad rarer compared to the smoothbores. But the rifled barrels are also a hair shorter typically. Some have rifled full-length barrels though. I have a couple. I don't use BB's in my 760's when I acquire them. Modern domed pellets work better in them.
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Taking my valve mods to another level for this 6th variant with a rifled barrel. Still just the 1 retention bolt opposite the TP, solder fill in the throat, and angled exhaust but 9/64 this time. Stem reduction to an extreme for me and first time I’ve attempted removal of material around the poppet head. Looking for a bit more power this time.
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Things have moved along a little faster with this 2nd modded 760. Implemented some ideas from my LW barreled 760 like; O-ring in between barrel & support, shims in the clam shells and shrink wrap on the hammer.
The only visible mod is to the probe. I dropped 1/16 inch piece of wire coat hanger behind the magnet to seat pellets a wee bit more and rounded the plastic slightly to ease passage past the O-ring. It will no longer pick up BBs from the reservoir. But I only plan to shoot pellets, since this has the rifled barrel.
While not to the same power as BackRoads’ 760. The results using the OEM cup and valve mods netted some big gains. JSB 7.87gr shoot over 680fps with 10 pumps and show some potential as do the few .452 diameter HN’s I’ve shot while checking fps.
It definitely does not shoot cheap crosman pellets well!
Topped it with a cheap Crosman scope. Starlings better beware.
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One last mod for this 6th variant 760. Added a trigger stop screw. I think it has definitely added me in being more accurate with it.
So is a 760 with a rifled barrel more accurate with pellets? 1rst - find the rite pellet! 2nd - do your part.