Avg. FPS 2400 24"

[Fred E Krugar]

Hey guys I am new here, so please be gentle.

I just got my 2400 in from crosman. And i was trying to check the fps and I was getting an average of 580 - 596 per 25 shots from one co2 cart. Is this correct from a 24" barrel? Should I be getting more or less? The factory 2240 shows it supposed to do 460 fps. Does the 24" barrel make that much difference?

Also on my first cart I could here gas coming from the barrel (like the valve was stuck open) the second cart did not do it . But the third did it again. Is there a quick fix for this random action?

One more thing if I just change to a heavier hammer spring would this increase the fps to any noticeable gains?


Crap sorry I put this in the wrong subject, Mods plz move.

[JEBert]

Freddie, 
Others on here report that barrel length does affect pellet speed up to 10 fps per inch of added length.  I haven't set up the chronograph yet so I can't comment further.  Sounds like you have a Custom Shop gun.  I am assuming you got it in .22 cal, yes?
Are you putting a drop of oil on each cart?  I haven't had an intermittent leak on mine (or ANY leaks for that matter) but when I forget the drop of Pellgunoil, sometimes I get several weak shots like the cart is barely pierced.  If that were my 2400, I would have to take the valve apart and look for some trash in it.
A heavier hammer spring might hold the valve open longer so you might get some more pellet speed there but since I have not tried it in any of my guns, I don't know but I will offer my thoughts on possible side-effects.  It will make it harder to cock and unless you install a drop-sear trigger, it will affect your trigger pull.  If you go heavy enough, you might start beating up your valve parts too.  There have been some reports of carts sticking in the gun and I'm wondering if heavy hammer springs have had anything to do with that.
Cheers,

[quickster47 †]

There appears to be an epidemic of leaking airguns coming from Crosman here lately.  Hope this is not a real ugly trend or harbinger of things to come.

You also must remember that Crosman never tells us exactly what pellet they use to achieve those high FPS numbers.  I mean, if I were to use some alloy pellet I could get some incredibly high FPS numbers from my stock guns.

Anyway, Jerry gave you some good advise.  Don't go changing the hammer spring in favor of stronger spring just yet.  Shoot the gun for a season and then decide what you want to do.  And don't forget to decide up front what you want out of this gun.

Carl

[Brent]

Those are nice numbers! In am thinking that is .177 numbers? A longer barrel does increase fps, as it let's the gas have more time behind the pellet, and get the gain of all the co2 pressure available. 18" seems to be the sweet spot, in all I have read.

Your shot count seems low, but seeing those fps numbers, it is shooting hard so that would explain that. If you want to get higher shot counts, try a lighter hammer spring.

Regarding your powerlet leaking (which would also explain the lower shot count if they are on those powerlets), try just tightening the co2 cap another half turn. You don't want to crank it down on the valve seal (that is also not good), but often a leak is just needing a touch more tension to seat the powerlet onto the valve seal a bit.

Theoretically a heavier hammer spring would help the hammer hit the valve harder and hopefully hold the valve open a touch longer, resulting in more co2 and power. As Jerry said though, it is also harder on the valve, and seeing those numbers now, not sure it would be that much more.

Hope this helps!

[Fred E Krugar]

thanks for the info guys. I did use the oil. But like I said it is intermittent.

To let you guys in on the whole story, I was at the crosman site to order a shoulder stock and a breech and the price came out  a little over $60. I saw the custom shop thing, well well what is this? So I built  this thing and it was only like $25 more and figured what the heck. The parts  I was ordering was for a highly modified 1377. I was just shooting this 2400 just to see how it does. I am just going to put the 2400 top end on the 1377 lower and turn it into a 1322. I may have to do some fitting but that is ok cause i have a welder, lathe, and end mill in the garage. : )  As for the 2400 I have decided to  just turn it into a pcp carbine, I have some titanium tubing I can use for the  tank. I have a .30 cal barrel already turned down to the proper size, just need a nice breech. (got suggestions)

So now you know...................................., the rest of the story,
Good Day.

[Hooper]

Hi Fred,

I looked at the Crosman Custom Shop stuff and did the same as you, just bought a 2400KT basically for the parts.  There is one issue you will probably run into when you try to use the 2400 top end on the 13xx.  The breech screw is in a different location.  On the 13xx it probably is up front while on the 2400 it's further to the rear under the bolt.  At least that is the way it was for me. (My 2400 was a .177).  You will most likely have to drill and tap another screw hole 4-48. 

[quickster47 †]

Hi Fred,

I looked at the Crosman Custom Shop stuff and did the same as you, just bought a 2400KT basically for the parts.  There is one issue you will probably run into when you try to use the 2400 top end on the 13xx.  The breech screw is in a different location.  On the 13xx it probably is up front while on the 2400 it's further to the rear under the bolt.  At least that is the way it was for me. (My 2400 was a .177).  You will most likely have to drill and tap another screw hole 4-48.

Hooper has a great point.  All, to my knowledge, 22XX main tubes have both front and rear location tapped for the 4-48 breech screw.  The 1377 only has the front location tapped.  You can drill and tap the other location pretty easy but then you will also need to notch the 1377 hammer or it will forever destroy that little 4-48 screw.

Carl

[crossliner]

Those are nice numbers! In am thinking that is .177 numbers? A longer barrel does increase fps, as it let's the gas have more time behind the pellet, and get the gain of all the co2 pressure available. 18" seems to be the sweet spot, in all I have read.

Your shot count seems low, but seeing those fps numbers, it is shooting hard so that would explain that. If you want to get higher shot counts, try a lighter hammer spring.

Regarding your powerlet leaking (which would also explain the lower shot count if they are on those powerlets), try just tightening the co2 cap another half turn. You don't want to crank it down on the valve seal (that is also not good), but often a leak is just needing a touch more tension to seat the powerlet onto the valve seal a bit.

Theoretically a heavier hammer spring would help the hammer hit the valve harder and hopefully hold the valve open a touch longer, resulting in more co2 and power. As Jerry said though, it is also harder on the valve, and seeing those numbers now, not sure it would be that much more.

Hope this helps!

No I should say it's a .22...My unmodified 2400kt w/ a 24" inch barrel in .177 can do 680+ fps. Best regards.

[Fred E Krugar]

Hooper has a great point.  All, to my knowledge, 22XX main tubes have both front and rear location tapped for the 4-48 breech screw.  The 1377 only has the front location tapped.  You can drill and tap the other location pretty easy but then you will also need to notch the 1377 hammer or it will forever destroy that little 4-48 screw.

Carl

Could I just use the hammer out of the 2400. I am just to lazy at the moment to start up the bridgeport. ( I am pathetic)

And thank you all for the responses. BTW it is the .22

[quickster47 †]

22XX and 13XX have different size main tubes and therefore, different size hammers.

22XX tube is 7/8" and the 13XX tube is 3/4".

Carl

[Fred E Krugar]

i was just coming on to say that they were not the same size then I read quicks post  lol