Sick 2240 coming to papa

[mr007s]

I had previously recorded higher numbers using Hobby Pellets and a poly tube TP. My hope is to transform this piece into strictly a shooter for the monthly comps. I have been doing several classes here and a few on the GTA site. It seems as though I am constantly sighting in and adjusting for the different distances and chosen pellets. I would like one to be set up for each competition and eliminate the constant zeroing. The two pumpers are set and both will return good consistent scores. With the addition of this next CO2 shooter I believe I will be set, if it has the accuracy I am looking for. Kinda wish I hadn't enlarged the valve and just ported it. I don't think I need all that velocity, just good shot count and steady numbers with low SD. I am thinking of turning a piece of brass to stick back in to bring the capacity of the valve back closer to stock, or just getting a stock valve to put back in it.

[quickster47 †]

I would keep that valve for some future project and just get a couple of stock valves from Crosman.  It's always good to have a spare valve or two hanging around.

Carl

[Mebits]

God would wish he could eat the food I am cooking right now, its wild goose legs confit, slow boiled in its own fat for 10 hours until extremely tender

Oh...man!

I am always too tired after cooking duck for guests to save the fat. I've been wanting very badly to do a pheasant leg confit. That or just fry potatoes in the fat at a later date.

I like the way you think, Oane.

[mr007s]

The once sick 2240 became a well healed 1740 today, at least temporarily. You can read about the mods preformed here, reply 14: http://www.crosman-air-pistol-owners-forum.com/board/index.php?topic=2914.msg27069#msg27069

I did replace the valve spring with a heavier one and elongated the barrel TP opening to .157 X .187.
The probe used remained a DC extended one I had as a spare. This barrel is a 10 incher.

The Chrony chart below reflects 4 ten shot strings. Ammo used was Crosman Premire Hollow Points, 7.9 grain. You can see that after about shot 30, things go down hill fast. Still haven't decided if I will replace the valve with a stock one or if it will stay .177. One thing for sure, it is much quieter now

[arkmaker †]

Wow, really lloks like 30 good consistant shots! I'll be adding my 10" barrel tonight if the stock transfer port is the same, otherwise I will have to wait until I can open up the barrel end a bit. I'm going with the stock valve, no mods for now. I should end up very close to you with a few FPS less due to your  opened up transfer port.
Rich

[mr007s]

Wow, really looks like 30 good consistent shots! I'll be adding my 10" barrel tonight if the stock transfer port is the same, otherwise I will have to wait until I can open up the barrel end a bit. I'm going with the stock valve, no mods for now. I should end up very close to you with a few FPS less due to your  opened up transfer port.
Rich

I will wait on a valve swap until your results are posted. Will be interesting to compare them. I just noticed the pellet wasn't listed. I will go back and add that info.

[mr007s]

The goal for this piece is to turn it into a nice paper puncher for the comps and have a high shot count. I am not pleased with a 30 shot count so I made a change. The 2 piece .177 barrel will be retained because I want a .177 C02 to be a little brother to the 2300KT. I realize that CO2 is more efficient with .22 cal and I accept that part of the equation.
  The modified valve was replaced with a stock one, only porting the exhaust for better air flow. All stock springs were utilized and a SS enlarged TP was installed. I had a home-made HDD that was affixed as well.
With the modified valve a good bit of exhaust could be seen from the muzzle, not so now and the report is noticeably quieter. I was able to get five 10 shot strings before velocity got below an acceptable level First shot registered 547 fps and last shot was 499. By shot 55 the fps was down to 429.

here are some comparisons of the before and after results

modified valve:String 1 avg.552  S2avg.534  S3avg.522
Stock    valve:String 1 avg.541  S2avg.534  S3avg.527  S4avg.517  S5avg.508


My thoughts are in comparing the two test is that the modified valve was wasting gas with the 10 inch barrel. The stock valve gave the same results, or better and a higher shot count.

Where do I go from here? I could move to to a 12 inch barrel which I would rather not. The 10" has a nice balance. Maybe try a lighter hammer spring or install a spacer in the valve to reduce volume. I probably don't need 540 fps for paper and am thinking around 450-475. Anyone want to offer suggestions as to how I can de-tune down about 100fps?

Thanks for any insight here.

[Gunhippie]

Well, maybe you need to stop modding the valves at all! Since the valve is open during the entire discharge phase, improving flow through the transfer port should also increase the amount of CO₂ leaving the reservoir.

Something else to try is the volume reducer from the 2300 valve. It's a little brass bushing that slips inside the valve, reducing the ID of the valve. I'm pretty sure the 2300 valve is the same as the 2240 otherwise.

My 2300S' average around 500 fps @ 65 F (.177, RSB Xact) with valves modded only for bulking--B&A fronts and cut-off piercing pins. Stock springs, etc. Since the guns are tube-bulked, shot counts would be meaningless here, but I still do get some visible exhaust from the muzzles.

Timm

[bdb12586]

To be the most efficient and power producing My thought would be that you would still want to open the valve as fast and hard as possible.  I would consider trying the modified valve with heavy spring to accomplish that, I would also, as gunhippie suggested, use a volume reducer. but still get the most out of the co2 you are using.

Then again  Iââ,¬â,,¢m not to smart.

[quickster47 †]

Personally, I think I would go back to a completely stock valve and maybe add the HDD and valve spacer to get your shot count up.  I think you will be pleasantly surprised at the power the OEM valve delivers.  Especially if you are just punching those dreaded paper targets. 

Carl

[mr007s]

I believe gunhippie hit the nail on the head! Yesterday I placed a reducer in the valve. The  usable shot count stayed in the 50 range but the fps averaged 499 506 494 501 and 480

Today I reduced the SS TP opening with an opening of .145. That gave me 90 usable shots with averages from 521 to 506. I should note that this was done with RWS hobbys instead of the CPHP's. That may explain the increase in fps over the previous test.

I haven't reduced the striker weight and may not need to. The Crosman stock transfer port opening is around .136. I plan to make a second reducer tomorrow with a hole size of .130 and install it. If I can get around 450 to 475 fps and a nice 100 or so shot count you may hear me yelling
All the testing has been done in the basement where temps are not ideal. With warmer weather around the corner I expect to see even better results once I can get outside.

[quickster47 †]

I've done some playing around with reducing the striker weight and it does make a difference.  On one of my 2300KTs with the 10.1" LW barrel I have the HDD and a lightened striker and my shot count is really good.  Somewhere around 80 to 100.  With the lightened striker I also went with the ProTop valve top because it took too many hits to puncture the powerlet.

Carl

[bdb12586]

007 that seams like a real good number ratio. Was that with your moded valve?

[NorthStaR]

Very neat Carl, not seen much action on people modding the hammer, nice.

I had an idea of an alt HDD - don't know if it would work, its just an idea!

It was to put a rubber cap on the end of the striking side of the hammer.
When the hammer strikes initially hitting the pin and then on the bounce (or restrike) the recoil is absorbed
into itself with the rubber as a shock absorber?

Would it work? I got the idea when the train pulled into the station this morning and I saw the buffers on the front carriage.
I have limited tools but I'll try it if I can find something suitable for the absorber and I need to get a spare hammer.