New Sheridan 2260MB: Here's my groups. What do you recommend next?

[fivestar45]

Did get the old protop sealed....a little toughter than the orginal,so I have to screw down a bit harder,but it works. Used what I think is a Discovery valve stem.

Still looking for a little bit more "squishy"seal material.

Never did polish it...cleaned it,but the dull oxidized brass from years of being in storage doesn't bother me.

Did shoot a bit faster than the orginal...likly due to less clutterand the smaller valve stem.  Which is NOT what I wanted,but  adjusted the spring tension a bit and it got back to the energy level I was looking for.
You would not have been thrilled with the plastic breech and the clamp on scope mount that that required. That plastic breech works well enough with the issue rear sights of the time,but consider that the barrel is just pushed into the plastic breech,NOT secured with set screws,just the metal transfer port interlocking the barrel in place.

Ribbonstone if you reduce the bore for the stem to 1/8"using the "Hobby Shop" brass tube bushing I think you will find the 13xx stem to be somewhere between the Disco, and the 22xx stem as far as hardness goes.


Considering th shape of the feeding systemof that mag...it's likely to be a bit pellet picky.....keep an open mind testing, likely there is something that will both feed and shoot well.

Ribbonstone if you reduce the bore for the stem to 1/8"using the "Hobby Shop" brass tube bushing I think you will find the 13xx stem to be somewhere between the Disco, and the 22xx stem as far as hardness goes.

[WilsonLR]

why are you going nuts with all the after market producers that resell crosman parts? ... the REAL question STILL hasn't even been considered....why does the barrel shoot so far right?

Yeah, to be fair, I started this thread with a couple directions for which I was seeking advice. And I clearly had the wrong expectation that the top of the line 22xx model should put down 1" groups on target at 10yds out of the box. Silly me.

But along the way to removing me and my old eyes, from the equation of a new rifle shooting 2-3" to the right that in spite of being the series top model, was the discovery it doesn't allow windage adjustment (Strike 1) and in experimenting, I ran across the problem of CO2 cartridges letting off half their load due to the finicky design of the valve face seal (Strike 2). Being the dang seal is 10" down the tube and hard to see, the question became: "Return it or fix it?" Pyramid said "send it back or replace the seal, my call." So I took the advice here, bought what I needed to tear it down and fix (including bore cleaning stuff). I opted for a more sure footed design that didn't depend on the non-universal definition of "Finger Tight". But I still had to get past the hairy brain dead .050 Allen Key breech screw (Strike 3) paying $5 shipping for $1.50 stainless steel Torx replacement.

So now the gun will take a cartridge reliably and following the assembly advice here to make sure the barrel was assembled correctly, it shoots exactly the same. But at least it takes cartridges at will, adjusts for power and I can tra la la along with lego a solution to my eyes when the rings come in, clean the barrel and see what other chocolates are in the 2260 box. One thing I know thanks to the Pro-Top/Adjuster fix is that at full power and 18.13g pellets, it will kill a think skinned hard headed iguana at 2 yds (albeit) off the kill shot to the right (Home Run on second time at bat). 

[WilsonLR]

duplicate post deleted

[WilsonLR]

I have to say, I'd love to see HYspd's tricked out 2260MB. Who's with me?

Today, I used these bore whips as they were the only ones I could find in stock. They are difficult to feed into the small breech of the 2260. The line gets hung up on the TP. After three pulls with Ballistol, there was no change to accuracy.

Attached is the factory crown on the barrel. What is the cotton swab test?

[mrbulk]

That is a GRAVmag 9s. It only supports specific pellets. I got the Croosman bersion that has an extra tube for Crosman pellets. It comes from the UK but you gotta grab one while they are available. Works like a charm. FIts under Standard/Medium rings.

https://www.airgun-parts-shop.co.uk/collections/all-crosman-products

Les, if you don't mind would you happen to know if the GravMag would fit a QB78? Mine is a steel breech. Thanks for any opinions.

[Arkmaker]

Just my quick take, but you should expect to be within a dime sized groups @ 10 yards with that rifle. It should be more than capable of it. My 2260 out of the box was with plastic breech and open sites. If not, I'd send it back for replacement.


I would go with the bug buster and forget open sights. More money, I know, but once done, your done. Plus the compact size fits it well.

[WilsonLR]

Les, if you don't mind would you happen to know if the GravMag would fit a QB78? Mine is a steel breech. Thanks for any opinions.

I don't know what the differences are between the 2260 and QB78 steel breeches. The GRAVmag clips to the 11mm dovetail. It's feed tube extends into the breech and rides on the probe. A spring in the GRAVmag pushes the tube into the open breech when the bolt is pulled back to cock the gun. The space between the end of the tube and the bottom of the breech is the right size for a pellet. When the probe pushes that pellet into the chamber, the tube recedes (against its spring) and the probe prevents another pellet from loading. Rinse and repeat.

Only certain pellets are supported due to the shape of the bore in the feeder tube. For example, the standard tube works for JSB Match Exact Jumbo 15.89g pellets but not the 18.13g variant of that pellet. Ditto the Crossman tube ... specific pellet shapes.

Once the plate at the top of the tube is adjusted properly, it deflects enough to let a pellet pass when under finger pressure while loading but does not allow the pellets to slide out. There are registration marks on that piece to help repeat the setup if/when you want to dump the magazine.

Here's some closeups.

[HYspd]

why are you going nuts with all the after market producers that resell crosman parts? ... the REAL question STILL hasn't even been considered....why does the barrel shoot so far right?

Yeah, to be fair, I started this thread with a couple directions for which I was seeking advice. And I clearly had the wrong expectation that the top of the line 22xx model should put down 1" groups on target at 10yds out of the box. Silly me.

But along the way to removing me and my old eyes, from the equation of a new rifle shooting 2-3" to the right that in spite of being the series top model, was the discovery it doesn't allow windage adjustment (Strike 1) and in experimenting, I ran across the problem of CO2 cartridges letting off half their load due to the finicky design of the valve face seal (Strike 2). Being the dang seal is 10" down the tube and hard to see, the question became: "Return it or fix it?" Pyramid said "send it back or replace the seal, my call." So I took the advice here, bought what I needed to tear it down and fix (including bore cleaning stuff). I opted for a more sure footed design that didn't depend on the non-universal definition of "Finger Tight". But I still had to get past the hairy brain dead .050 Allen Key breech screw (Strike 3) paying $5 shipping for $1.50 stainless steel Torx replacement.

So now the gun will take a cartridge reliably and following the assembly advice here to make sure the barrel was assembled correctly, it shoots exactly the same. But at least it takes cartridges at will, adjusts for power and I can tra la la along with lego a solution to my eyes when the rings come in, clean the barrel and see what other chocolates are in the 2260 box. One thing I know thanks to the Pro-Top/Adjuster fix is that at full power and 18.13g pellets, it will kill a think skinned hard headed iguana at 2 yds (albeit) off the kill shot to the right (Home Run on second time at bat). 

just a quick reply haven't had time to read more than first 2 lines..

the discovery, fortitude, maximus are the upper tier of the 22xx line...the 2260MB is a discovery crossed with a 2240...

and at 10 yards you should be stacking 3 out of 5 pellets once you are used to the airgun...groips over an inch to the right at only 10 yards high lights an issue

a vague possiblity is that your hold is not straight up and down (my personal nemisis) when sighting...

[WilsonLR]

I do feel I checked for cant in my testing. I was considering spending twice the 2260MB money on a Discovery plus another $50 for China pump thinking I'd have less fiddling with the power plant. LOL. But I wouldn't have the budget for other fun stuff like reactive targets, possible red dot or scope, etc. Really, for me, I needed a nice plinker with enough power to dispatch the occasional iguana. I expected iron sights to do the trick but in the end, old eyes made that difficult. Maybe tomorrow the weather will be good and I can lock it down for a test. 

[Ribbonstone]

Just judging by the pictures....the crown of that one looks a lot nicer than many Crosman barrels. 

Get a scope on it (and I'll bet right now there will be some minor issues with that), shoot slow in a temp.stable enviroment,and see what it can really do. 

Don't give a hoot-n-*(&^ where the groups form at first...if it wants to cluster pellets,we'll figure out how to get the clusters where you need them.

[HYspd]

I have to say, I'd love to see HYspd's tricked out 2260MB. Who's with me?

Today, I used these bore whips as they were the only ones I could find in stock. They are difficult to feed into the small breech of the 2260. The line gets hung up on the TP. After three pulls with Ballistol, there was no change to accuracy.

Attached is the factory crown on the barrel. What is the cotton swab test?

here's a pic of her kt1300..and [edit] my 2260MB in it's current non pcp configuration

[lefteyeshot]

Nice guns big buddy.

[HYspd]

That is a GRAVmag 9s. It only supports specific pellets. I got the Croosman bersion that has an extra tube for Crosman pellets. It comes from the UK but you gotta grab one while they are available. Works like a charm. FIts under Standard/Medium rings.

https://www.airgun-parts-shop.co.uk/collections/all-crosman-products

Les, if you don't mind would you happen to know if the GravMag would fit a QB78? Mine is a steel breech. Thanks for any opinions.

that would be a no, the bolt body diameter of the QB is huge compared to the 13xx/22xx bolt body diameter...

[edit] as in approx 9/16" on the QB and 1/4" for the crosman....

[WilsonLR]

here's a pic of her kt1300..and [edit] my 2260MB in it's current non pcp configuration

Have you ever shot that non-pcp configuration with iron sights? DOes it shoot right by chance? :-)

[HYspd]

those pics i posted are old...both are built on 2260 tubes currently running co2, with 18" barrels hers is .177 mine is .22 (awaiting a pcp update) and have Discovery bolt handles...


the Muddy Girl has the kt series adjustable trigger group and the black has a 1701T trigger group with an alchemy airwerks hammer...

fitting the kt1300 pumper fore end to the 2260 tube required an adapter hacked out of a piece of aluminum angle stock....

[WilsonLR]

Got tired of waiting for Optics Planet exchange so I picked up some junk low height rings on Amazon. Boom. Zero'ed the scope and the attached group at 10yrds was right in the middle of the left/right range (the high one was me). With low height rings, the turrets have to be forward of the GRAVmag magazine which puts the eye relief a little forward than I'd like and I scuffed a finger on the ring while working the bolt. I can learn to deal with that.

HOWEVER, since I had to remove the rear iron sight if I wanted to use the scope flip up covers, I leveled the gun using the steel breech and threw a level on the barrel's rear sight seat. I'm thinking that's not right:

[lefteyeshot]

If you want the Gravmag behind the turrets you could try an offset mount/ rings. If that's to close to the eye, a slip over recoil pad could help and give a little more pull length. Options?

[WilsonLR]

With low height rings and this scope, the gravmag forces the position. But the height is maxed out even with a shim so medium height rings means a lot of holdover shooting for my backyard range. I’ll look at the off set rings again. Thx.

What does everyone think about The rear sight seat not being in the same plane as the breech?

[Ribbonstone]

Back at the rear end, the ports should line up....so the hole in the barrel lines up with the hole in the breech and lines up with the transfer port which lines up with the port in the valve body.....basically 4 holes.

If that is happenin,can consider that flat to have been machined wrong.

IF that alignment isn't happening, then the barrel is somewhat rotated and that flat may have been machined level.

[WilsonLR]

Thanks Robert,

I'm counting three things cause the lineup.
1) 1322-015 lines up the tube center axis and breech center axis rotationally
2) 1322B027 makes breech center axis and tube center axis parallel
3) TP aligns rotation of barrel with rotation of tube

Because the breech and tube are aligned via 1322-015, therefore the barrel center axis is aligned with the breech center axis subject to the tolerance of the TP. Man that seems like a very important alignment to depend on such a small mechanical connection. Am I missing something?