Crosman’s 2400KT carbine: Part 5

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3
Part 4
Part 6
Part 7
Part 8

Today’s report is the continuation of a guest blog from reader HiveSeeker about his Crosman 2400KT.

If you’d like to write a guest post for this blog, please email me.

Over to you, HiveSeeker.

Crosman 2400 KT
The 2400KT CO2 carbine is available exclusively from the Crosman Custom Shop.

This report covers:

• A reminder of the two guns
• Barrel length and velocity
• Can you help? Part 2
• New thoughts on barrel length

Part 5 was going to be the Crosman 2400KT .22 velocity test. However, I’d already reported that this gun delivers almost identical velocities in both .177 and .22. When I stated in Part 4 that barrel length alone does not appear to account for this, a number of questions came up. I’d already researched this and knew why I had drawn that conclusion; but without that information, some blog readers had questions. So, let’s jump ahead to what I had already put together about barrel length and its relationship to velocity before moving on.

A reminder of the two guns

Crosman 2400 KT Sassy Sandy
The Sassy Sandy is a target carbine in .177 with 10.10-inch Lothar Walther choked match barrel, black custom shoulder stock, black trigger shoe and black muzzlebrake.

Crosman 2400 KT HiveSeeker
The HiveSeeker is a light-duty small game and pest hunter in .22 with 18-inch barrel, simulated carbon fiber custom shoulder stock, black trigger shoe and black muzzlebrake.

Barrel length and velocity
We’ve mentioned barrel length a couple times already, and we’ll finally address that topic here. A longer barrel means higher velocity because the CO2 has a longer distance over which it can exert pressure on the pellet, generating more speed. We’ve already discussed the .177 Sassy Sandy and .22 HiveSeeker having the same velocity, but that statement is only partly true. With an 18-inch barrel close to twice the length of the 10.10-inch Lothar Walther barrel, the HiveSeeker has a decided advantage. How much? Let’s see if we can find out.

Although I couldn’t get a word out of Crosman on Custom Shop gun velocities, one of their customer service reps did tell me that the velocity difference across all the available barrel lengths was about 50 fps. In my research, I came across B.B.’s blog, How barrel length affects velocity in a CO2 rifle, which showed almost exactly the same result. There, B.B. tested a Quackenbush XL rifle with a removable 7-oz. CO2 reservoir. It started off with a .22-caliber, 20.125-inch Crosman 2200 pneumatic barrel. B.B. cut down that barrel in 1-inch increments as he conducted his test. You’ll want to check out that blog for yourself, but below is B.B.’s velocity table, reproduced with his permission.

I’ve reversed the order of the original table to show velocity gain as the barrel gets longer, rather than velocity loss as the barrel was cut down. Problems cropped up when the barrel was cut down below 13 inches, so the comparison had to stop there.

Crosman 2400 KT barrel length vs velocity
Velocity increases with barrel length — up to a point. This table is modified from B.B.’s blog, “How barrel length affects velocity in a CO2 rifle.” The data is presented in the reverse of how B.B. presented it. Data is from a Quackenbush XL rifle with a removable 7-oz. CO2 reservoir and .22-caliber, 20.125-inch Crosman 2200 pneumatic barrel.

As you can see, velocity increases with barrel length up to 19 inches, and the maximum increase is 52 fps — just what Crosman Customer Service told me.

But at 20 inches, velocity drops. Once the CO2 has expanded inside the barrel and is no longer under enough pressure to push the pellet faster, friction takes over and the pellet begins slowing down. Further digging revealed the following from one of B.B.’s earliest blogs on the Crosman 2240: “According to tests I ran [on the 2240] with The Airgun Letter, a 24-inch barrel will slow the pellet back down to about where the 10-inch barrel is. A 16-inch barrel would be ideal, and you might see over 500 fps from a stock valve.” (Crosman’s 2240: Are we having fun, yet?) When Rick Eutsler sent B.B. the HiPAC kit for his Crosman 2240 conversion to air, he told B.B. that the 14.50-inch barrel would be the optimum length.

A somewhat longer barrel also seems to perform well, as I found with my 2400KT — though I think a different factory valve may also be helping. You’ll recall that the Crosman Outdoorsman 2250XE also happens to have an 18-inch barrel. When B.B. tested that particular gun, he said, “First, because it has an 18-inch barrel instead of just a 10-inch barrel, you get optimum performance from each CO2 cartridge. However, there’s a point of diminishing returns, which happens to be somewhere around 16 and 18 inches of barrel. After that, the pellet loses some velocity from friction. So, the barrel length on this carbine is anything but an afterthought!” (Crosman Outdoorsman 2250XE_Part 1). In the barrel-length-and-velocity blog, Crosman confirmed that 18 inches was optimum for a 2250. B.B. also concluded that 14 inches would probably be the optimal limit for a CO2 .177 barrel.

To summarize, all my data indicates that the 18-inch barrel is giving the HiveSeeker .22 about a 50 fps advantage over the 10.10-inch barrel on the Sassy Sandy .177. This isn’t enough to explain why the .177 has the same velocity as the .22.

Can you help? Part 2
What you just read was written as Part 6, almost verbatim. At this point, I was planning to discuss the different 2400KT stock velocities contributed by the blog readers and, perhaps, draw some more concrete conclusions about .177 and .22 velocities in this gun. I’d already scoured several Crosman modding forums before starting this blog; but while modded velocity data abounded, the stock velocity data was scarce and contradictory. I would still like comparative stock velocities for the 2400KT. If you can supply it, please remember to mention barrel length and pellet weight. If you’re actually throwing your gun back on the chronograph, please use pellets close to 7.9 grains in .177 and 14.3 grains in .22. Thanks in advance!

New thoughts on barrel length
Part 4’s comments made me do more thinking about why I got similar velocities in the .177 and .22 2400KT. Barrel length is a major factor. But with both the manufacturer and actual field testing indicating that the maximum velocity spread for a CO2 gun is about 50 fps across all barrel lengths, a longer barrel is simply not enough to make a .22 shoot just as fast as a .177. When we compared the Browning 800 Express, we saw a velocity difference of more than 200 fps between .177 and .22. I won’t compare a springer to a CO2 gun any further here, but I definitely expect a .177 to shoot a lot more than 50 fps faster than a .22! If that’s as much velocity as can be accounted for by a longer barrel, I’m forced to conclude that something more is going on with the 2400KT.

I already mentioned that, when looking at the Crosman Outdoorsman 2250XE, B.B. commented that a 14-inch barrel would probably be the optimal limit for a .177 CO2 gun. If that’s true, then velocity would start to fall off with a .177 barrel longer than 14 inches. The maximum velocity increase would be limited to only about 4 inches of added barrel length — not 8 inches — for the 10.10-inch .177 barrel. In other words, the 8-inch disparity in barrel length between my .177 and .22 2400KTs may be making even less of a difference than the 50 fps we’ve attributed to it so far.

The question remains: What’s going on with that .177? Blog reader Buldawg76 mentioned one fact I hadn’t considered — that the .177 Lothar Walther is a choked barrel. I already knew that, but didn’t consider the possibility that choking might actually slow down the pellet — dropping velocity a little closer to what I might expect from a .22. That’s one possibility that a comparison with the standard (unchoked) 10.10-inch Crosman .177 barrel might confirm. A related possibility I’d already considered was that Crosman might assemble differently a pistol ordered with the Lothar Walther barrel, perhaps with a different valve, in order to create a match gun with optimally stable (and also lower) pellet velocity. Again, someone with stock 2400KT velocities from a shorter .177 Crosman barrel might be able to provide an answer.

Before we wrap up today’s blog, I’d like to note that most of the questions that arose from Part 4 were related to much higher barrel-length velocity increases on modded guns. I’ll simply state that a CO2 2400 that’s been converted to air, valve-swapped, and then pressurized to 3,000 psi is no longer a CO2 2400. Please feel free to share your modded velocity data. For direct comparison to the unmodified Crosman 2400KT CO2 Carbine that’s the topic of this blog, please stay with similarly unmodified pistols.

So, this was our detour on the way to Part 6. We still have unanswered questions, but I hope the blog readers better understand how I arrived at the conclusions I did. Next, we’ll conduct the Crosman 2400KT .22 velocity test, which will be less puzzling and a lot more interesting!

115 thoughts on “Crosman’s 2400KT carbine: Part 5

  1. Hiveseeker,
    Good to hear from you again!
    B.B.,
    How much effect would having more surface area contact in.22 than .177 have?I could be wrong(again) but it seems like I recall a formula from one of your older Co2 Big bore blogs. I’d like to read it again also so it may be easier for you to just link it for us all to rediscover.

    Reb



      • I had it pulled up(Wasn’t one of B.B’s) and almost shared but didn’t wanna get spammed and have been rummaging through my history trying to find it again for about 30 mins now. It’s most likely true being as it’s not the first time I’ve ran across an article mentioning it and you can bet if I run across it again I’ll try to share it here.I was just so positive B.B. would know exactly where to find it. 🙂


  2. I always hated to assume.

    Valves,barrels, calibers,lengths. Here’s a new one, the weight of a pellet verses another. The sealing of the skirt. How the head of the pellet fits the rifling.

    How can one caliber be compared to another?

    How does the diameter of the two different calibers affect velocity.

    Then when the pellet leaves the barrel what about the coefficient of the drag the shape of the pellet creates when it fly’s?

    I bet chronying the gun at different distances would create different results with your caliber comparisons. Retained energy comes to mind which is apart of velocity,weight and drag.

    And what will the next part reveal?


  3. Hiveseeker
    I read the report and you have made a lot of good points and observations which should provoke some more good discussions here much like part 4 did, but the reference to the hipac and the 14.5 barrel length being optimum I have to disagree on the statement by Rick Eutsler as I have two 2240s with 177 caliber barrels, one is a 24 inch disco barrel bought from GF1 and the other is a 20 inch Daisy Avanti barrel machined to fit the crosman steel breech.

    I have recorded velocities in the low 800 fps with a 2200 psi fill out of both guns using CP 10.5 pellets with a shot count of 20 so I don’t know what Rick was using as a pressure or if he had an adjustable hammer setup or just stock spring and valve but HPA and CO2 are very different in their operating pressure so I believe that 14.5 inch barrel is not necessarily the optimum length, but the I have the piercing pin cut off the poppet valve and the transfer ports opened up to 3/16″ and ice maker tubing for a port seal so it was not just a stock 2240s with a hipacs and my hipacs had two extensions whereas the one BB reviewed was just a hipac with no extensions so I had more air volume to shoot with.

    I have my hipac ends out getting disco tubes made to replace the very poorly designed hipac setups and one tube will be 14.5 inches for the 20 inch barreled gun and the other will be 16.5 inches long for the 24 inch barreled gun. I am hoping to get around 850 to 900 fps with a shot count of around 25 with each gun and I just got an email today that they should be ready by weeks end so I will have some numbers hopefully by months end.

    BD


    • Buldawg
      I guess I will be like Hiveseeker. I already know the results as he says above.

      Well guess what I have been shooting 2240’s for years with different caliber barrels and different legnth barrels and different weight pellets and different shape pellets.

      Let’s see what Hiveseeker says. Because technically I did not have a custom shop gun and I would be assuming.

      Maybe there will be something new to learn here.

      And notice I didn’t say anything about a pcp. I’m talking about Co2 powered 2240’s I had in the past.

      But I still have that question in my mind about what outcome is Hiveseeker looking for.

      Like there is something magical there.

      I guess I’ll buy a couple like he’s got and take them apart and see.

      And it seems this is all old news if BB’s already covered it in reverse order of some sort.


      • OMG I forgot the most important thing about Co2.

        Were both guns chronyed in the same environment.

        Most importantly was the guns the pellets the Co2 cartridges and room temperature the same.

        If any of that changed the comparison would not be true.


        • Gunfun
          I agree with you and to also know the outcome to some extent as well but I did forget about ambient temperatures in relation to CO2 as I only have the P08 non blow back pistol in CO2 so it does nor get shot much.

          I was merely pointing out that BBs review of the hipac 2240 and Rick Eustlers comment about 14.5 inches as being an optimal length barrel for the Hipac may hold true with a single hipac setup but is not correct when it comes to a larger volume reservoir of air to use and when the guns parts have been modified to take full advantage of the higher pressures that HPA provides. I know you already as you sold me your 2240 hipac gun with the 24 inch disco barrel.

          The condition that Hiveseeker shot the two guns in play a very important role in his recorded results and unless those can be duplicated exactly then the results cannot be accurately compared.

          I too am interested in the overall information he is after for the conclusion in this review.

          BD


        • Gunfun1,

          Appreciate your weighing in with your experience. The only outcome I’m looking for is an explanation as to why my two different caliber guns shoot at the same velocity. Yes, they have different barrel lengths but everything I’ve dug up so far says that will only account for around a 50 fps difference for a CO2 gun. I have not found specs on a commercially available dual-caliber pistol where the velocity difference between .177 and .22 is that close (it’s usually 100 fps or so), so something else besides just a difference in barrel length seems to be going on. I am all ears for a verifiable explanation, or enough data that shows something different than what I’ve concluded so far. I think they call that process “Science” or somesuch!

          Temperature effect on CO2 performance is a big factor, I agree. My logs showed the temperature ranged from 86-88 F for the .177 test, and 84-86 F for the .22 test. So yes, both guns were tested under essentially identical conditions.


          • Hiveseeker
            I just read through your recent comments to people of what may be the cause of the velocities from the gun.

            You named of valves and other things but you keep overlooking one important thing.

            The size of the hole in the transfer port orafice. Buldawg talked about his modified guns of opening the transfer port size up.

            Crosman has different size orafice inside diameters for different guns throughout the years. The 1377,1322 and 2240’s and so on.

            That orafice is what controls the air from the valve to the barrel.

            I would say that Crosman is trying to control the power output of the guns from the custom shop to keep the velocities pretty close to equal no matter what combination of barrel and caliber is used.

            I’m willing to bet that your .22 caliber gun has a bigger inside diameter orifice that transfers the air from the valve to the barrel than the .177 caliber gun.

            There is no other reason that I can see that would make the short barrel heavier pellet and bigger .22 caliber keep up with the smaller lighter.177 pellet with a longer barrel.

            Other than pellet fit to the particular barrel. Maybe your .177 barrel is on the small diameter side and the pellets are fitting the barrel tight. And maybe just so happens that the .22 caliber barrel is sized more correctly to your .22 caliber pellet your using.

            Let me know what you think.


            • Gunfun1,

              I would not bet against you on a bigger transfer port! I think a different valve is involved, and I think more CO2 is being expended on the .22 (30 good shots per cartridge) than on the .177 (40 good shots). You accidentally flipped the specs around; the longer barrel is on the .22 which accounts for a good percentage of the velocity increase approaching that of the .177, though as I’ve said I don’t think that’s the whole story on the equal velocities.

              I don’t think pellet fit is a big factor, as I tested a wide range and their velocities fell out pretty evenly on my weight-versus-velocity graph (not much indication of a particular pellet being faster or slower than expected based just on weight).

              Good thoughts. You’ve covered most of what I thought of, and then some.



    • Buldawg76,

      Thanks for the detailed response and added data. The 14.5 inch barrel was what Rick Eutsler had told B.B. would be optimal, though my own experiences and information from other blogs point more toward 18 inches for a .22 being optimal for the 2400KT, which I do mention in the next paragraph. I included Rick’s comment because the barrel length is long for a pistol, just as mine is, and because we’ll be taking a closer look at B.B.’s mods in Part 6. Of course, the conversion to air and the valve change make the modded 2240 a different gun, and I agree that I can’t make a direct comparison there — it was a statement that pointed in the same general direction I was headed in regards to barrel length. I found a wealth of data (like yours) showing much higher velocities in both .177 and .22 with modded guns, and — yep! — a longer barrel produces more velocity, which was the more general point I was aiming for. Apologies if I missed the mark!


      • Hiveseeker
        No apologies are necessary as I misunderstood or did not get the point that you were making but just wanted to make sure that you understood that a custom gun is nothing more than Crosman building the gun instead of you doing so and that the 2240 that BB tested could not be used as a comparison for your 2 2400s with CO2 versus HPA.

        I am waiting for part 6 to see what else you have researched and uncovered for us.

        BD


        • Buldawg76,

          Agreed that the 2240 conversion to air cannot be used in a direct comparison, though we’ll have good reason to take a closer look at it coming up in Part 6.

          If Crosman uses stock parts for their Custom Shop, then I do think that at the very least they know which parts (I’m thinking valves in particular) may be optimal for a given gun, and possibly a given bun-barrel combination. The .22 shoots very fast for an unmodified CO2 gun!


          • Hiveseeker
            I am very interested in your part 6 report as it sounds to be a good report by what little you have eluded to it containing.

            I am not sure bot I would just about bet that the parts that Crosman use in the custom shop guns are just everyday off the shelf parts and the valves in 2240s and 2400s and most all of their CO2 guns that are based on the same platform as the 2240 and 2400s are the exact same valve assys as you can go to their website and pull up schematics for the guns in that platform and the part numbers for the valve, trigger parts and everything but the tube and barrels will have identical part numbers. The tubes and barrels are different due to the 2240 tube is shorter than a 2400s tube as well is the barrels but the 2400 uses an extended cartridge piercing cap as compared to a 2240 so that it will contact the cartridge to seat it for piercing by the valve. They all use the same 12 gram cartridge. you just got lucky with your Hiveseeker custom gun in that it has very well matched components so it shoots faster than some others but I do not believe that they hand picked the particular parts in either of your guns but just pulled the parts from the shelf to assemble the guns you ordered. I may be wrong as I have been many times in my life but in this case I don’t think I am. If you have confirmed otherwise or can confirm otherwise please correct me in my assumption if you know different as it would be good info to know.

            BD


            • Buldawg and Hiveseeker

              I haven’t looked. But does Crosman show a different part number for the 2240 verses the 2400.

              That is a big thing that I have seen with the Crosman guns that use that transfer port orifice design. Some of their pcp guns come with two transfer port orifices that you can change for velocity and shot count.

              One of the guns that I have had in the past is the Crosman 1720T. It comes with two transfer port orifices.

              I really believe from what I have seen with the other Crosman/Benjamin guns it will be the transfer port that gives the biggest amount of air flow control in their pneumatic and Co2 guns.

              Spring guns is a different story than pneumatic and Co2 when talking transfer port hole size.

              Pneumatic guns will increase velocity with a bigger transfer port hole. A spring gun could slow down with a bigger hole.



              • Gunfun
                I did not look at transfer ports as they most likely are different as well and I did not think to look at the numbers for them as all my guns get the ice maker tubing mod as it is just way less restrictive to the smooth flow of air but then my guns are all HPA as well and not CO2.

                I cannot help myself as I have always had the need for speed and or power even though in air guns it may not always be the best combination for performance and accuracy as I am learning very fast about those combination must work together to be consistent and therefore accurate.

                BD


                • Buldawg
                  No problem with speed.

                  As long as it don’t affect the guns recoil characteristics.

                  That’s what’s nice about pneumatic air guns. Increase the air flow to the barrel and they will shoot faster. And without having to do any work to the valve. And most of the time you will not increase recoil.

                  Try increasing the velocity on a spring gun and see what happens with the recoil or shot cycle.

                  Its so much easier increasing power on a pneumatic gun then a spring gun and maintaining good shot cycle characteristics.


                  • Gunfun
                    That’s why we are trying to keep the velocity up on our spring guns and reduce recoil at the same time and you have done better with that than me so far but I have not given up yet and know I can get there also with my 40 and most definitely with the 48 as it is already fast enough so its just a matter of reducing recoil.

                    That’s why my CO2 guns are now HPA as it easier to shoot fast and more stable in extreme temperature ranges. I have shot two FT matches with temp below freezing and my Mrod never even complained at the least and worked much better than I did in those temps.

                    BD




                • Isn’t that essentially what the adjustment screw on the side of a Marauder does — restrict the size of the passage the air flows through… While the two adjustments on the back control how hard the striker hits the valve, and how long a stroke it has.


                  • From what I’ve read that would be correct but the MRod is much more expensive than these little pistols and I’m sure features like that are part of the reason why. I was wanting ta way to get the same results for a less expensive alternative. It’s a lot more work to strip a gun than to turn a screw but if that’s the way to get it done on this less expensive gun, so be it.




  4. I’m sorry, but I am really confused. If I have this right, both carbines are shooting at almost identical velocity. The differences in the carbines is the .177 has a 10 inch barrel and the .22 has an 18 inch barrel. Nobody seems to be able to figure out why? Could it be that somebody is overthinking the whole thing?



    • This was supposed to be the “un-confusing” blog installment! It’s been a while since Part 4, but during the shots per fill discussion my .177 and .22 graphs both showed maximum velocities of about 560 fps for both calibers. A .22 airgun is usually much slower than a .177 with the same powerplant (for example, 200 fps slower in the Browning 800 which is available in either caliber).

      The longer barrel on the 2400KT .22 definitely contributes to more velocity, about 50 fps more from both what Crosman told me and B.B.’s barrel length test showed. But that’s not enough advantage to make the .22 shoot just as fast as the .177 — that’s the big question. I don’t have an answer, but I hope that stock velocity data from other 2400KTs with different barrels than mine might give us some clues.


      • HS,

        But they DON’t have the same powerplant! You are testing 2 different airguns — each with it’s own powerplant. To test the same powerplant, you need to install one barrel on the other gun.

        Even though parts may be identical, there is no guarantee your 2 guns perform the same. You cannot assume that.

        B.B.



        • B.B.,

          You’re right of course. I was thinking very specifically of the 12g CO2 cartridge that is the identical power supply for both guns, but the “powerplant” would really have to include the breech, valve, and barrel as well.

          The question today’s blog poses is how one particular breech and valve combination can push a .22 pellet just as fast as a similar (same model gun) breech and valve combination pushes a much lighter .177 pellet — using the identical CO2 supply! The laws of inertia would seem to say “Nope!” to the heavier pellet being just as fast. A longer barrel on the .22 helps, but based on what my research turned up that still doesn’t fully account for the equal velocity of the .22 pellet.

          Again, I don’t have the answer, but I’ve presented some of the interesting findings my research turned up and hope that more stock velocity contributions from the Pyramyd Air blog crew will shine some light on this.


          • Just musing…

            CO2 has a fixed pressure, dependent upon temperature — the point at which it vaporizes from the liquid state; increase the pressure and more liquifies to cancel it out…

            Assume a flat bottom pellet…

            .22 has a surface area of 0.038 square inches
            .177 has a surface area of 0.0246

            Say the CO2 is at 800PSI

            That means the .22 has 30.4 pounds of force pushing on it, while the .177 has only 19.7 pounds pushing against it.

            The .22 has a circumference of 0.69, .177 is 0.53. Use this as a stand-in for frictional surface against the barrel.

            The .22 has nearly 54% more force pushing it, with only 30% more “friction”…

            The only variable I’ve not accounted for is the difference in the mass of the pellets.


      • Hiveseeker
        BB is right as even though both guns are 2400s the parts are not identical unless you do what is known as blueprinting in the automotive world by measuring and insuring that every single part or tolerance dimension is exactly the same and at the exact dimensions or tolerances that the designers and manufactures stated in their Blueprint drawing of all the components in each gun which would take a large amount of time and possibly money to accomplish.

        I am not positive but I will just about guarantee that the valves hammer springs and all other part in a custom shop are off the shelf components and are not modified or improved in any way from what would be in a store bought 2400. All the custom shop does is give you a choice of easily adapted readily available part from crosman to build a 2400 to your preference of grips , barrels, sights, trigger shoes etc, but nothing is different than what you would get if you bought a stock 2400 and bought the items separately yourself. All the custom shop really does is save you a few dollars and allow people without the knowledge to build their own custom gun to have one made for them.

        BD


        • Buldawg76,

          I don’t believe you can buy the 2400 in a store, but regardless it would certainly make sense for Crosman to use stock parts as much as possible. With their robust family of CO2 guns they have a lot of parts to choose from — and I think they use them very wisely. Some parts are obviously identical between them, but I think the valve and internal parts will be tailored to the caliber — and perhaps barrel — being ordered.


          • Hiveseeker
            I just scoured Crosmans site and it appears that the 2400s are only available thru the custom shop and are based off the 2250 Ratcatcher family of guns as looking thru the schematics the 2400 does not share any tube or valve components with the 2240/ 2300 family of pistols. It does use 2250/2400 valves and tubes which are somewhat different than the 2240/2300 in that the tubes are longer and the valve may have a larger volume inside for CO2 to supply for propelling the pellet. I did not go into looking at individual valve components to see if things like the valve spring or poppet valve or cartridge seal or valve bodies may have the same part numbers because as an assy they show different part numbers but that does not mean that some of the internal parts of the valve assy may be the same as 2240/2300 or not the same.

            The main thing is that you are happy with the guns you bought and enjoy shooting them is the main goal and purpose. Myself I have never been able to leave something stock as there is always more to be gained from tuning or reworking/ engineering it to perform better or the way I want it to perform.

            BD


      • Also should have added: Props to RidgeRunner for doing a concise job of summarizing today’s blog–no, you’re not confused! I don’t have all the answers, but learned a few things about barrel length and velocity while researching this, and hope that more stock velocity figures from my fellow readers will shed some light on what I’m finding in my two guns specifically and the 2400KT in general.


  5. Depending on what velocity he’s getting outta his, I may just keep mine on Co2. I had forgotten about Co2 being more efficient in larger calibers.
    Thanks Hiveseeker! I’m glad I didn’t already order a buncha stuff to put into it.

    Reb



      • I was pretty gung-ho on getting it on HPA but in no big rush due to the expense involved in setting the gun up AND fill equipment. I had also planned on using bulk Co2 which would be much less expensive in the short run and if I can get 650-700 fps outta Co2 without having a gun that’s too awkward to hunt with I would probably stay there for a while before having to unload the rest of the $. Right now I’m considering a BNM breech and shroud to keep the fun factor up & neighbors happy.Still gotta get the gun in before I can do much else.



        • Hiveseeker
          Another thought maybe they have different strikers and striker springs in your two guns.

          If one gun is hitting the valve harder or lighter that will change the velocity.


        • Oh, I’m stilll hangin’ in there.Just got off the phone with customer service and found out the conf. # for my wasn’t the same as the order #, so now I have my order# and she said I’d be receiving the delivery email in about 3 weeks but also mine didn’t look very complicated so it should be out before the more intricate ones. “So,it’s still being built?”
          “That sounds about right.”
          When can we expect your next installment anyway?
          Reb


  6. HiveSeeker,

    Since these airguns should be identical except for the caliber and barrel lengths, have you tried swapping the receiver/barrel assemblies between the two and checking their relative performance again? That would be an interesting test.

    Paul in Liberty County


    • Paul,

      That would be a very revealing test! However, I’m pretty sure that at the very least the .177 and .22 have different valves. In fact, I think the .22 is shooting as fast as the physics will allow, but that the .177 might be “stepped down” in velocity, possibly for match accuracy purposes. I’ve started this blog as a non-modder, and don’t want to void my warranty on the guns, but Buldawg76 and Gunfun1 are posting some pretty tantalizing modded velocity figures for this family of Crosmans!


      • I don’t blame you. I didn’t get the ext. warranty on mine because I’m always up for getting in there & clean up whatever they missed before too many pellets go through it. I may do the icemaker line mod but I’ll be hanging on to my restrictor in case shotcount becomes an issue.
        Gotta pace myself nowadays!

        Reb


  7. One step in the right direction would be to control for pellet weight. A jsb monster in .177 weighs over 13 grains. Select a
    22 pellet of similar weight, chrony both guns, then compare the disparity in velocity. Of course there will be many other variables left, but this would factor out a major one.


    • Diaboloslinger,

      That would also be an interesting test, though I’m fairly certain that the constricted barrel of the .177 would contribute to a much lower velocity than just the pellet weight would account for. The laws of inertia would demand that the heavier pellet be slower (we’re talking about the same .177 gun now, not two different guns and calibers), which would again raise the question: Why is the .177 slower than the .22?


      • You’ve got my curiosity peaked. I guess the only way to nail this down would be to set up a test with the same pellet weight, valve, ambient temp, barrel length, etc., etc…. However that would not explain whats happening with YOUR guns. I still wonder if the custom shops use caliber-specific valves in their guns, as the 2300 series’ valves have different part #s than the 2240 and 2250. For some reason, my .177 2400kt with the choked walther barrel likes a much higher fill pressure with a weaker hammer spring than both my 2240 (18″ barrel/.22cal) and 2400 (24″barrel/.22cal). The .177 likes a 2200 psi fill, while the others like a 1800-2000 psi fill with a stiffer spring.


  8. My new bone stock 2400KT, 177, 18″, shot CPHP, 7.94(average of 10 weighed) at an average 614fps.
    For a direct comparison. IIRC, temp was about 55-60. Muzzle was about two feet from first set of rods.


    • Hello Tom King,

      Hard data? Thank you, sir! This is exactly what I’m looking for!

      Right off the bat, this is 54 fps faster than what I got with the exact same pellet in my 10.1 inch barrel. That — again — comes very close to the 50 fps velocity difference Crosman told me I could expect across all available barrel lengths. However, I shot my gun at 84-86 F so your reported velocity at 55-60 F is going to be low compared to mine. This really makes it seem like the velocity difference across barrel lengths is going to be (a lot??) more than the 50 fps I was told.

      B.B. speculated that a 14 inch barrel would be the longest optimal length for a CO2 .177, so now I’m even more curious to see data for a stock 2400KT with 14 inch barrel! Would it be slower than your 18-incher? Or is the 14-inch barrel even faster, and the 18-inch barrel is already slowing the pellet down?

      I came across a very limited number of stock velocity figures on several different Crosman modding forums. They were too inconsistent to draw conclusions from, but some of them suggested increasing .177 velocities all the way out to the 24-inch barrel.

      A little more data, a lot more questions! Thanks again, Tom, and those of you who have some stock velocity figures lying around, please don’t hold back!


  9. I think a feasible 5-10% variance between one gun and the next and the 15% extra performance instilled by the longer barrel pretty much covers this disparity, there will be a velocity drop due to the choke, though minor.
    Starting to look a bit like tilting at windmills


    • Dom,

      If we get some more stock velocities posted, we might be able to firm up some of our speculation. Most of the multi-caliber pistols I could compare had a velocity difference wider than 10-15% between the .177 and the .22 version. However, throw in a little more velocity loss due to the choked barrel and we might be approaching a full explanation for the velocity difference in my 2400KTs.


      • Absolutely, calibre upon calibre 177 tends to be fairly inefficient, I had two barrels for a Wehrauch HW35 I once owned, it would give me 570 fps in 22, for around 10.3fpe and 690 fps in 177 for 9.2fpe, both with RWS Hobby….what it didn’t do is give me 570fps in both calibres, which is the oddity with your situation.
        However, the barrel length and machining variance, and possibly, the choking sounds like a perfectly plausible explanation,
        Shame you haven’t got an Crosman unchoked 22 barrel knocking around to swap the 177 out with for curiosities sake.


        • Dom,

          CO2 guns and pneumatics (including PCPs) tend to be more efficient in terms of muzzle energy with heavier pellets, often around 20% more efficient in .22 than in .177 within the same model gun. Springers, on the other hand, tend to be more efficient with lighter pellets.


  10. Back in 2008, B.B. posted a blog entry that included reference to a few long out of print books.

    /blog/2008/08/answers-to-airgunners-questions/

    “Then get Frank W. Mann’s classic, The Bullet’s Flight, From Powder to Target.”
    “Hatcher’s Notebook will tell you the answer to why …”
    Both of these and more are freely available in PDF format from:
    http://castpics.net/subsite2/ClassicWorks/

    “… Sir Ralph Payne-Galwey’s 1903 classic book The Crossbow.”
    This one is available to read as independent web pages here:
    http://www.crossbowbook.com/contents_1.html

    Another book or two is still in copyright and so is not freely available, as is “War Baby” by Larry Ruth.

    W. H. B. Smith’s book is not freely available. The Table of Contents can be found here:
    http://books.google.com/books/about/Smith_s_Standard_Encyclopedia_of_Gas_Air.html?id=1treAAAAMAAJ

    What may be a good deal for Smith’s book is here:
    http://www.secondstorybooks.com/pages/books/7-94-1190969/w-h-b-smith/smiths-standard-encyclopedia-of-gas-air-and-spring-guns-of-the-world

    Today’s blog post seems a reasonable spot to mention these, although they are not directly related.

    Lastly, a link that may have been better offered in relation to the Colt Single Action Army BB revolver or even the Daisy 1894 Western Carbine; this one offers a lot of information including two full online books by the web sites owner, “Single Action Sixguns” and the “Book of the .44” that includes hand guns and lever action rifles.
    http://sixguns.com/

    Aside from this blog, I believe I have my 2015 gun reading list nearly complete already.

    ~Ken



      • John, the pages listed do not include air gun information. Here is a page you may find interesting.
        http://www.arld1.com/
        Scroll down little and you will come to a series of animations, a few of which are specific to spring air guns. One of them is titled “8 milliseconds in the life of a springer”. You step through the cycle by clicking on the dots that are labeled, “First Stage, Second Stage”, etc. You can also find “Click here” below the animation to open in another tab or window in full screen view. Text is included to explain each stage of the cycle. Another animation regards recoil of springers and it also goes through the cycle. I hope you find this interesting. ~ken





            • Yeah Ken, I know. I’ve read that and the Cardew’s and the wordy technical articles in Airgun World, everything i can find. It is difficult to write unambiguously about a subject involving so many variables with the terminology, vernacular, nomenclature, dialects, slang, etc. to deal with. Always looking for more clarity. 😉


        • Ken,

          Thanks for that link. It looks really interesting. Animations with descriptions sound like the perfect learning aid. Can’t wait to check it out. Saved to favorites.


        • Ken,

          Just checked out your link.

          H-O-L-Y C-O-W !!!!! That is just plain,.. drop jaw amazing! And I might add, so easy to use. I happen to have a TX, so it was a real surprise to see it featured in some of the demos.

          Maybe the best thing I have ever saved to “favorites”.

          I will have to say though, I have about about 30 of B.B.’s articles saved to your 1,….so you got a bit of “cetchin’ up” to do…..;)


          • Chris, my thinker may not be as good as it once was, or how I like to think it was, but have read B.B.’s archives back into something B.C. Thankfully, they are still available so I may stumble onto the ones you have thought of. ~ken




  11. B.B.,
    Before I blow the whole morning trying to find verification of my earlier statement I’d like to ask you about the Co2/spring guns. Anything you could point me in the direction of?Just curious about this newfound(to me anyway) means of propulsion.


  12. BB,
    Pyramyd sent out an advertisement on the Benjamin BullDog today that says “Big Bark, Little Bite!”. The saying makes it sound like a loud but anemic gun (like all bark, no bite). I guess they mean to say that the gun is powerful but cheap but it doesn’t come across that way.
    I recommend they change the advertisement.

    David Enoch


  13. Just tried to order a Bronco for my nephew’s Birthday on the17th. Customer service says it’s been discontinued. I recall someone mentioning this would happen but I really didn’t think it would happen so soon. I wanted it for it’s 2 bladed trigger to kinda match his .223 Savage and had hopes he’d earn a scholarship. I’ve sent my 953 over for Daddy to get him started with but it’s a bit much for him to cock and pump. I saw another MendozaM-8? with the same 18# cocking effort but I don’t know anything else about it. Is it pretty much the same gun?


  14. A tip, for anyone interested,..

    I have been looking into scope levels. 1)..for setting up gun and scope, and, 2).. for actual shooting.

    I picked some plastic RV levels that have an adhesive back, at Wally World over the weekend. Cheap, 2 in a pack. Popped off the plastic back and then popped out the level tubes. I now had 2 scope tubes.

    Next, I got some “Gorilla Glue” at work. 2 part epoxy in a syringe. Using 2 VERY strong magnets that I had previously bought for something else, I glued the level tubes, stood on end, to the magnets.

    Since scopes are mostly alum. and plastic, I figure I will stick one to the steel screw on the windage adjustment and the other to the back-side edge of the trigger guard to check for “cant”. Once done, I could leave the one on the windage knob for shooting.

    I will get 2 more levels to check scope level to barrel level,..only glue the levels (layed down) on the magnets.

    The magnets are incredibly strong! Find them in the craft section of your local store. They are literally the size of a…. shirt button! You can apply layers of tape to weaken the pull to the steel so as not to pull the level loose from the magnet. Hopefully the glue will hold.

    Hope this idea gets some people “up and running” in using levels for shooting and set-up.


    • Update on the scope level idea,

      The trigger guard on the TX is non-ferrous, so the magnet will not stick. I did stick it to the windage knob and fired the gun. The level did slide back a little, but did not fall off. It would need to be repositioned for each shot.

      As for the glue,..it did hold,.. but while playing with the levels this morning,..1 tube came off while pulling it off some metal. The glue stuck to the magnet better than the plastic. I will try some 2 part putty type epoxy next time.


  15. Last summer I personally compared a 2250XE with a 24″ barrel & a 18″ barrel. Right after shooting the 24″ I changed to the 18″ with no other changes done to the gun. Tested with CPHP 14.3 same 80 Degrees temp.
    10 shot avg. w/ 24″ barrel = 649 fps.
    10 shot avg. w/ 18″ barrel = 582 fps.

    Would Crosman put a 24″ barrel on a 2260 if a shorter barrel would be better? This is an easy test to do and really should be done by someone (you) who has more creditably than I.


    • BillK,

      Welcome to the blog. Your results are atypical, but they are real. Stuff happens like that all the time.

      As for Crosman, they don’t test all barrel lengths to see which is best. They know from experience that certain lengths work and they make and sell those. The exhaustive testing is being done by hobbyists.

      B.B.


  16. BillK,

    Welcome to the blog. Your results are atypical, but they are real. Stuff happens like that all the time.

    As for Crosman, they don’t test all barrel lengths to see which is best. They know from experience that certain lengths work and they make and sell those. The exhaustive testing is being done by hobbyists.

    Also you tested in the summer. The temperature has a ,ot to do with CO2 velocity, as I am sure you know. I don’t mean the valve and barrel length, but perhaps the heat recovery time.

    B.B.


  17. BillK,

    Welcome to the blog. Your results are atypical, but they are real. Stuff happens like that all the time.

    As for Crosman, they don’t test all barrel lengths to see which is best. They know from experience that certain lengths work and they make and sell those. The exhaustive testing is being done by hobbyists.

    Also you tested in the summer. The temperature has a lot to do with CO2 velocity, as I am sure you know. I don’t mean the valve and barrel length, but perhaps the heat recovery time.

    B.B.


  18. A few years ago I modded a 2240 with a 24″ .177 barrel and drilled the valve. I remember my chrony readings were around 680-720 fps with crosman hollow points.
    I just ordered a 2400kt with a 24″ .177 barrel and am planning to mod the valve. I was hoping I would get about the same results.


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