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PostPosted: Fri Dec 05, 2014 7:00 pm 
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Location: Vancouver
Hey Crosman fans, here's another 'golly gee I just got my first 2240 in .22" and here's all the cool stuff I've done with it so far' post. Maybe a couple of useful bits included, for future reference in case others want to try the same stuff. I've pasted the same text below as I did in an existing 22xx mod thread, as maybe it's good to have it all in one place for reference in looking at performance of an individual pistol's modifications.

So last is first; today I made a new hollow bolt probe:

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Even with a slightly fatter O-ring on the stock probe which comes in the steel breech there was still the problem of pellet depth - the stock probe is too short to push my pellets (JSB Heavy) more than half way over the barrel port. Meaning a BUNCH of pressure is crashing into the skirt of the pellet, which is just foolishness. So I checked around, rejected the delicate looking thin steel probe design, and went with a new 1/4" steel probe. It was a lot of boring fuss getting the dimensions laid out just right, but I proceeded carefully and everything came together perfectly. I wanted slightly beefier threading on the knob too so I drilled slightly larger and threaded the new bolt in 10-32, then used a die to cut matching threads on the stock steel knob stem, trimmed the end off, then chucked it up in my little lathe and turned it down so it wouldn't hang up in the breech slot.

The probe itself is 0.25" steel stock. Chromed. A leftover from I don't remember what. I bored out a 1/16" hole in the back and used some Hot Stuff CA to glue in a tiny neodymium magnet, so the bolt doesn't fall forward when loading with the muzzle tipped down. The dimensions are as follows. Sorry for the mixed measurements. I'm 53, and part of the transition to metric generation who never will get used to using one system or the other. I freely switch between them as convenient, without any logic at all.

4.65cm - overall length
0.25" - diameter
8.5mm - distance from front of probe to centre of O-ring groove
31.5mm - centre of threaded bolt hole to centre of port hole
4mm - inside diameter of probe hollow, which ends right at the back of the port hole
5.2mm (0.205") - diameter of hollow probe
5mm - port diameter, drilled with 1/8" bit then milled out with a round nosed bit

My average velocity went up about 20fps owing to the lack of leakage and probably in part to the better flow direction for the gas. Wasn't looking for a performance improvement. In fact I've carved away quite a bit of steel from the hammer to even out CO2 release and flatten the curve somewhat. Anyway, that's the hollow bolt probe, and I highly recommend making one of these to any tinkerer as the result loads more reliably (even pressure on the pellet skirt when pressing the bolt forward) and doesn't leak. Here's the rest of what I've done with the 2240 so far. HiPAC should be in the mail soon, so I can break the CO2 emitting habit and get busy with my Gehmann pump. A nice goodie bag arrived from rrdstarr today including a sweet aluminum side plate he got from Derek Vineyard. Funny thing is, the bolt won't draw all the way back with that plate screwed down... so I'll have to figure out what it is that isn't quite right about it and carve it a little. Nice thing though! He sent me a bunch of other spares and neat bits to play with including one of his steel RVAs for the hammer spring. I like using a wire stock, so I'll probably be brazing a mounting tube of some sort on for that before installing it.

- Made a plastic rear tube cap (a harder plastic than Delrin called Ertalyte, but only because I'm out of Delrin rod) for mounting the same wire stock I use on my Brocock Atomic. It's a snug fit into the tube. Holes drilled and tapped for the Crosman screws. Most of the length drilled to 3/8" for a snug fit of the aluminum rod. A 1/8" hole drilled vertically just behind the steel tube and the end of the wire stock carved to match, so it's easy to set it vertical and it stays there. Inside drilled out for the hammer spring.

- Crosman steel breech added. Not a 'mod' exactly, just replacing the incredibly delicate and cheap plastic one before ever using the pistol.

- Drilled a 1/8" hole in the rear of the bolt and glued in a 1/8" neodymium magnet. The bolt as-stock kept falling forward if I tipped the pistol forward, rather annoyingly, so the magnet sticks lightly to the hammer pin and prevents the hammer going anywhere until I push it forward. These little magnets from Lee Valley Tools are so handy for so many things!

- Filled the grip panels mostly full with hot glue. A trivial thing, but the hollow-sounding cheapness of the plastic grip panels just bothered me too much. Filling with a long stick each of hot glue makes them quiet in handling. Some day I might make wooden grips, or not. Not in much of a grip carving mood just now.

- Clipped the sear spring about 1 turn and stretched it a bit, then put a used .22"LR brass casing on the upper cut end of the spring after polishing it. As folks say, this helps ease trigger pressure enormously, and coupled with polishing all the meeting faces in the trigger/sear group the trigger is very comfortably light. Also did the 'Nirvana mod' on the trigger (why is it called that?) just getting rid of the superfluous tongue sticking out the front of the trigger.

- Put in the 18" barrel (.22") I got from Hacked2Pieces a while back. A bit of a loose fit in the breech, so I used a 1/4" wide strip of aluminum muffler tape to shim along the top and that made for a snug fit. Before mounting I followed someone on network54 forums advice and used a long wooden rod and a wad of 0000 steel wool, snugly packed in, to polish the rear-most 80% of the barrel 100 strokes back and forth. Then polished the last 20% 5 strokes each way. Theory being it's a poor man's 'FX smooth twist' bore polish, easing the passage of the pellet most of the way then tightening up slightly for the critical last few inches. I don't see any change in velocity, but accuracy may have improved slightly. Hard to confirm with a good red dot sight, but I don't really want to put a scope on this carbine just now. Might get a low profile, small diameter Leupold at some point, but for now the Burris is just right.

- Used a Dremel grinding bit to carve away a few grams from each side of the hammer, in aid of reducing wasted gas and extending the shot count. With the right preload on the spring and the hammer weight reduced I ought to be able to get quite a few shots per fill. Polished the hammer to make it move more easily. Lubed with graphite powder.

- Filed down the heavy stampings along the right side of the main tube. I've always hated words printed all over things where they're not relevant. I really don't need to read a cautionary statement every single time I use the pistol. A few quick coats of epoxy 'appliance' paint and some heat and it's more or less adequately painted for now... though it seems I didn't bake it long enough and it's somewhat soft. I'll do a proper paint job sometime when I'm getting 'finished' with modding. (Yeah, like that ever happens.) Polished and painted the barrel band as well, getting rid of the ugly casting seam.

- Mounted a Burris Fastfire III red dot sight. Very compact sighting solution. Much easier for my old eyes than open sights and helps keep the weight to a minimum for this very lightweight carbine.

When I receive the HiPAC I'll probably make a second barrel band of some sort, as I'll be using one extension for more air. Going to shroud the rather long and skinny-looking barrel all the way back to the breech with a length of epoxy painted aluminum tubing I have which is just under 3/4", exactly the same as the steel breech. Hoping to make a nice clean line all the way from back to front with the same diameter. Without a high-rise breech I'll have to mill out the rear section to have it lay flush on the air tube.


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PostPosted: Fri Dec 05, 2014 7:03 pm 
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Location: Vancouver
And here's a snap of the gun itself, as apparently there's a 3 image limit per post.
Attachment:
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PostPosted: Fri Dec 05, 2014 10:33 pm 
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GerardSamija wrote:
And here's a snap of the gun itself, as apparently there's a 3 image limit per post.

Gerard use photobucket :wink:

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PostPosted: Fri Dec 05, 2014 10:51 pm 
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Location: Vancouver
Yeah I could. Mostly I've used my own webspace for images I post in forums, but lately I've been lazy and just use a board's internal attachment regimen. Guess I should go back to hosting my own... Photobucket and similar sites can be frustrating for their practice of deleting images if they're not acceded after a few months. I see too many broken image links in too many forums for just that reason. Makes for frustrating image searches when researching various stuff.


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PostPosted: Fri Dec 05, 2014 11:56 pm 
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Joined: Wed Jul 16, 2014 1:24 pm
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Location: Vancouver, BC
Very interesting mods so far! It's great to see people enjoying customizing their 2240s. I'll check through my parts to see if there's anything you may want.

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Mike

FX Streamline .22 - Optisan Mamba Lite 4-16X44
Hammerli Pneuma Elite 10 .22 - Bushnell Elite 4200 4-12X40
Custom Crosman 2240 w/ LW barrel - Vortex Strikefire
Remington AirMaster 77 PAL rated - CenterPoint 3-9X40


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PostPosted: Sat Dec 06, 2014 7:14 am 
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Location: Canada
Yes keep posting this stuff. I'm a newbie to the 2240 so this is very interesting and helpful.

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PostPosted: Sat Dec 06, 2014 11:31 am 
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GerardSamija wrote:
Yeah I could. Mostly I've used my own webspace for images I post in forums, but lately I've been lazy and just use a board's internal attachment regimen. Guess I should go back to hosting my own... Photobucket and similar sites can be frustrating for their practice of deleting images if they're not acceded after a few months. I see too many broken image links in too many forums for just that reason. Makes for frustrating image searches when researching various stuff.


I'm not so sure if the images disappear from hosting sites because of your explanation or people just end up delete the pic's from there hosting site like. Then again I cant speak about other photo hosting sites I've only ever used photobucket.
I've been using pb for a long time never had an issue with pic's getting deleted unless I delete them myself. :wink:

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PostPosted: Sat Dec 06, 2014 12:18 pm 
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Well good for you. Unfortunately I've not been so lucky with Photobucket. Signed up on January 14th of this year, and since then have seen 2 images and 2 videos vanish for want of viewers. The message was brief but to the point: no one had viewed them for more than 90 days and so they were deleted. My guess was that they were promoting some sort of premium account or the like. I really wasn't interested in sticking around to discover more, so I stopped using the account.


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PostPosted: Sat Dec 06, 2014 2:27 pm 
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That's interesting Gerard I do believe you but I've never heard of that happening before, been using pb for 8 years never had an issue so far.

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PostPosted: Sun Dec 07, 2014 2:16 am 
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Location: Victoria, BC and Clarkston, WA
Let's get back on track here guys!
Gerard great job at explaining what all you did to improve your 2240! This isn't your first rodeo and I think you did a real good job on the probe and creating your own stock instead of using the affordable Crosman plastic stock.

I'd still like to find a wood 2250 stock.
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PostPosted: Mon Dec 08, 2014 1:28 pm 
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Check this one out, too!

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FX Streamline .22 - Optisan Mamba Lite 4-16X44
Hammerli Pneuma Elite 10 .22 - Bushnell Elite 4200 4-12X40
Custom Crosman 2240 w/ LW barrel - Vortex Strikefire
Remington AirMaster 77 PAL rated - CenterPoint 3-9X40


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PostPosted: Mon Dec 08, 2014 1:54 pm 
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Joined: Tue Oct 13, 2009 1:27 am
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Location: Vancouver
That's a very pretty piece of work! A bit heavy for my tastes, but beautiful, and the walnut looks to be of excellent quality.


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PostPosted: Mon Jan 05, 2015 4:04 am 
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Location: Vancouver
Well I've been tinkering away since New Years, finally finding a few hours to work on the 2240 again. My HiPAC with 1 extension tube arrived before Christmas and I used that at 2,000psi for a little while, testing with high pressure air as I worked on other elements. With the arrival of 2015 I've upped the pressure to 3,000psi. Which made for some misadventures with seals... Unfortunately, for whatever reasons, the two black 'special' seals Powermax supplied to go to that pressure both failed. Chewed to an ugly pulp by the pressure. I had tried screwing the HiPAC hand tight as Powermax recommends but the air just leaked right away, so I'd go a bit tighter... still leaking, so I had to really tighten the thing down until it stopped leaking. Then the seal would blow. So I made a delrin seal for the front of the valve. That worked great.

But then the fill nipple seal stopped working. A bunch of experimenting later and I resolved this (the stock tiny O-ring was being distorted on filling, blowing out sideways and stretching with my hand pump's input) by both polishing the inside front end of the HiPAC front tube (which was REALLY badly machined, not a proper sealing surface at all as it was so rough) and putting in a 90 durometer urethane seal about 8mm diameter. Works perfectly.

And then the valve poppet seal failed. A bit of searching turned up posts about this transparent plastic seal Crosman puts into these pistols failing all the time, mysteriously, though the brass valve seats are in perfect polished condition just as mine is. Just too weak for higher pressures I guess. So there was another adventure, making a new seal as I tweaked the valve stem and spring pressure to cope with the high pressure. A few failures, then yesterday I made a whole new poppet out of a nylon bolt and an old worn out drill bit. I first put some modelling clay on the end of a dowel, wrapped it in tape except for the tip, and pressed it onto the valve seat to take an impression. This gave me something to copy into the nylon on my lathe. I carefully turned it down until it was an exact match, then drilled the hole for the drill shaft. Ground and polished a concave area in the shaft to let air flow by more easily. Put it together using a lighter spring (the 3Kpsi air does a great job pushing the valve closed so very little assistance needed from the spring) and tested it by blowing into the input end. Sealed perfectly even with lung pressure!

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Because of all the seal problems I'd found myself getting more and more annoyed with having to unscrew the brass valve. I hate gripping such things with pliers, and even leather-padded pliers were leaving the odd mark. So I filed a couple of flats on the small end for a 5/8" box end wrench. With the other end firmly mounted in soft jaws in my vise this makes opening and tightening down a breeze, and it's really easy to do with a bit of care and a decently sharp file.

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PostPosted: Mon Jan 05, 2015 4:35 am 
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You'll see that the delrin seal is a rather floppy fit in the face of the valve. Well, it's a bit difficult getting a stiff plastic washer as big as the base of that opening in through the much smaller diameter top end of it. Guess I forgot to take a picture after solving this. What I did was gently hammer the top end of the brass down until it was almost a firm fit on the delrin, hammering from the outer edge and then right on the face. So the washer is quite well centred by brass. Bit of a cludge, but, well, I was getting tired and frustrated with all these leaks. At some point I'll probably chuck the valve in my lathe and turn down that face a bit, replace the delrin with a bit larger washer and then tap it into place again. If I need to. So long as it doesn't leak there's no real need.

Another source for leakage was the transfer port. Not that this was a critical area, but wasted air is wasted air, so I wanted to get that tightened up. My solution was to ream out the steel of the steel breech and the barrel port while attached together, then polish the newly conical bore to a very smooth finish, then make a delrin transfer port adapter to match. The result is this, a small tube which is conical at one end and cylindrical (actually very slightly tapered for easier insertion into the rubber washer once that's inserted into the main cylinder hole made to receive it) at the other. Didn't measure, just eyeballed it while looking from the polished port to the plastic in the lathe and back again until it looked right. The result presses into the steel very firmly, deforming just slightly in about the middle of the cone where contact is strongest. The one I'm using has a bore of 4mm, or 0.150".

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The smaller one delivered too steep a curve in my tested shot strings going up and coming back down from optimum pressure, so instead of restricting air flow at the transfer port I've focused on hammer weight reduction and reduced hammer spring tension to regulate velocity and shot count. I've also carved the slot in the cylinder longer for hammer pin travel, as my new valve stem is several millimetres shorter than stock and I found that the much lighter hammer was having trouble pushing the valve open with full pressure in the valve. Valve lock was one of the hardest things I was banging my head against but the combination of a longer hammer pin slot, longer spring with no preload, lighter valve spring and shorter valve stem have resolved that neatly. I'm getting very little wasted air per shot as the dwell time has been significantly reduced.

Let's see, what else... Oh yes. I've permanently affixed the 3/4" barrel shroud, blending it into the steel breech with steel filled epoxy putty, the JB Weld brand. Tough stuff. So no need to use a barrel band at that juncture and there's a clean line from the back right up to the front of the HiPAC where I've used a little home made barrel band, cut from 1/4" aluminum plate. And tonight I got much of the paint job done, now that the bulk of the internal stuff is done. I still want to play with hammer spring length a little, shorten it just a bit at a time to find where it'll still open the valve at close to 3,000psi but deliver an even flatter curve throughout the fill. Right now I'm seeing a rise from a full pressure tube up to peak velocity of about 6.5%, then a fall of about 6% down to the same as initial velocity. A 12.5% range isn't fantastic, but it's better than I was seeing with CO2 and better than I was getting in my initial setups at 2,000psi so I'm on the right track. Just needs a bit more tweaking of hammer impact and preload I think. rrdstarr's steel RVA has been such a huge help in figuring this stuff out! And soldered to a copper tube, which I then lined with UHMW polyethylene, it's also a great base for my 3/4" shoulder stock!

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Paint's drying, so I can't put it together at the moment for pictures. When it's dry in a couple of days I'll follow up with those. Haven't bought the scope I want for this yet so I'll still be shooting with the Burris Fastfire III for a little while, but soon it'll be wearing proper glass. So far in my testing this carbine is proving startlingly accurate, so I'm looking forward to bringing it out to Mission for my first ever visit to the monthly FT meet this month! Already warned my wife I'll be needing that day for myself... so the politics are taken care of well in advance.


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PostPosted: Mon Jan 05, 2015 9:01 am 
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Lots of work and experimenting with those 2240s. But thats where the fun is with them. I have a valve from I dont know what, with that nylon seal on the stem ? Anyway. It had the flat face like yours and I was having trouble getting it to seal. I remembered that the seal on my Sumatra was cone shaped into the sealing surface, so I stuck my stem in a drill and with some fine sandpaper I cone shaped it. It seals perfectly now and seems less hammer strike is needed to open the valve. And air flow around the seal in better also. Of course I'm only assuming it does. I cant test it. Also I only ever run my Hipac at 2000 psi.
Keep at it. The holy grail is in there somewhere.

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