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Thread: Custom Disco/22xx Hunter Carbine (Pic Heavy!)

  1. #1
    Senior Member sholo's Avatar
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    Custom Disco/22xx Hunter Carbine (Pic Heavy!)

    WARNING! - This is a LOOOONG post, so take your bathroom break now, grab a snack and either a beer or coffee (depending what time of day it is where you are) and settle in!

    This is going to be somewhat of a "bass-ackwards" type of build as I will be starting off with the stock mods first, then do the running gear later as I get them done. Also, I feel I should warn you that this will be a rather long, drawn-out build as I still need some custom parts done and that won't be until well into the New Year...I can hardly wait!

    First, a little background on the build...

    I've been wanting to build a somewhat compact, "bush-proof", small game hunting PCP for some time now that was tailored to my specific needs/wants and this is what I came up with. Except for a few pieces that need to be done on a lathe/milling machine by a skilled machinist... (which I am not :cry: ), most stuff was done with "caveman" tools and lots of elbow grease!

    Parts include:

    Shortened Disco tube (4" shorter than stock)
    Disco valve (modified), fill adapter & cover, hammer spring and modified hammer
    Extended valve front from Joe @ HPASports
    M-rod pressure gauge
    20" LW barrel (.22 cal) threaded 1/2"-20 NF to accept Hatsan air stripper
    Hatsan air stripper
    7/8" OD Carbon fiber shroud
    P-rod trigger group
    Custom repeating breech and bolt
    Custom Crosman shoulder stock
    Custom forearm
    CenterPoint 4-16x44mm SF scope w/side wheel

    Now that we have the preliminary babbling out of the way, let's start the build!

    As I stated earlier, I wanted a "bush-proof" gun meaning I needed a stock that not only was custom fitted for my long LOP and large hands, but would also be able to handle trekking through bush, branches, rainy weather and just generally harsh conditions without getting all beat up in the process (or caring too much if it did get some "battle scars"). Hmmmm....I guess a nice walnut stock is out of the question then... I had a couple extra Crosman skeleton stocks and thought, "Perfect, they are pretty tough as well as being light...just need to beef it up some to be more comfortable to shoulder is all". This is where I should point out that I have never tried this before and pretty much figured things out as I went... . Here is how it was done....

    I have an old 2240 grip frame and tube that I use to trial fit things on so I attached stock to it and started the process. First thing I did was to take some 80 grit sandpaper and rough up the stock where I planned on building it up, as well as sanding that Crosman logo off to make it a little more clean looking. I also ground off that little nubby that sticks out on the bottom of a 22xx grip frame as it always felt awkward in my hands (it sticks out right where my pinky finger naturally wants to rest). Then I started adding Bondo to the grip - yes, that's right...Bondo!
    m_Crosman Stock 002.jpg

    Don't worry...I know it's pretty crude right now, but it gets better looking as we go!

    Once I had a thick blob on I gingerly grabbed the grip and gave it a little squeeze so it would mold to the shape of my hand before it hardened. This was a slow process as the Bondo would set rather quickly, so I had to do it in several stages (one side at a time), building it up a bit more each time until I had it roughly to the size/shape I wanted. Then it was mostly sanding and shaping the contours, adding a bit here and there as needed. Note: If you are wondering why the bottom finger groove looks out of whack, it wasn't a screw-up (really, it wasn't!), it's just where my pinky finger naturally wants to rest...
    m_Crosman Stock 004.jpgm_Crosman Stock 007.jpgm_Crosman Stock 008.jpgm_Crosman Stock 014.jpg

    Once I had one side pretty well roughed out, I then started the whole process all over again for the opposite side:
    m_Crosman Stock 015.jpg

    Now that I had the grips mostly done (still have some fine tuning to do to match nicely with the forearm) I turned my attention to the forearm. This was made by laminating two pieces of 3/4" plywood together, then slowly shaped it to fit the gun. Used a router with a 3/4" half-round profile bit to cut the rough groove for the tube, then finished it off with a 12" long, 3/4" diameter wooden dowel wrapped in 60, then 120 and finally 220 grit sandpaper. Next I inletted for the trigger group and guard so that most of the trigger guard was hidden within the forearm. Once I was satisfied with the fit to the best of my limited abilities, I then carefully measured where the gauge would be and drilled it out with a 1" Forstner bit in my drill press. Thankfully (and with great relief) it fit perfectly! I wanted to attach the forearm as cleanly as possible (i.e- no visible band) so I purchased some super strong 5/16" diameter x 1/8" thick Neodymium (rare earth) disc magnets and inletted/glued them into the forearm. Pic shows only two, but I ended up adding a third one just behind the front one as two just wasn't quite enough. Between the magnets and the tight fit around the grip frame/guard (it actually "snaps" into place around the guard) it is very solid and takes a bit of force to remove from gun.
    m_custom stock 004.jpg

    Now that the forearm was done, I finished touching up the shoulder stock so there was a nice transition from stock to forearm. Once that was accomplished I turned my attention to the rear of stock. Started by first adding an adjustable butt plate and lengthen the LOP to accommodate my ape-like arms. The two extension pieces are 1/2" Delrin rod that I threaded 1/2"-20. Then drilled/tapped the rear of stock the same and screwed them into place, filled the inside (cut-out section of stock) with more Bondo and sanded smooth for a clean look. Adjustable butt pad is from an AR2078LE and I made the aluminum backing plate out of some scrap 1/8" thick material I had laying around. It is attached to the extension rods (which are drilled/tapped 10-32) with 10-32 x 1 1/4" long low profile socket head cap screws:
    m_Custom Crosman Stock 018.jpg

    Next up is the adjustable cheek piece. I made it from a 6" long piece of 1.5" ABS pipe cut in half lengthwise and rounded the ends off. The aluminum rods to adjust the height are 3/8" diameter x 3 1/2" long and is attached to the cheek piece via two 8-32 x 1/2" long low profile SHCS down through the top of cheek piece:
    m_Custom Crosman Stock 005.jpg

    Stock was drilled 3/8" to accept adjustment rods and drilled/tapped the sides of stock 8-32 for the 3/16" long set screws to lock them into place. Rods have 1/8" recesses drilled into them every 1/4" creating a positive lock for the set screws to fit into:
    m_Custom Crosman Stock 016.jpg

    Now that I had the stock to my liking, I borrowed an excellent idea from a member on another forum and applied three fairly thick coats of cyan..a..c...??.....Krazy Glue to all Bondo'd parts to seal them and create a hard protective coating, then 4 coats of truck bedliner spray to all components. Much to my surprise, the bedliner spray almost perfectly matches the factory Crosman shoulder stock.

    All I have to do now was modify my P-rod trigger group to fit stock. Will cover that in my next post as I seem to have reached my limit of 10 attachments per post....
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  2. #2
    Senior Member sholo's Avatar
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    All I had to do now was modify my P-rod trigger group to fit stock. First thing I had to do was smooth out the frame so it would slide nicely into "new" stock. This meant removing the bump-out for the safety (no safety on gun anymore) as well as the little tabs to locate the factory pistol grips. I also removed that aggravating little nub at the bottom of grip as that is right where my pinky finger likes to sit comfortably. One other area that has always bothered me on a 22xx frame is the rear portion (where rear screw is located) as it always rubs on the base of my thumb, so I removed some material giving it a more slanted profile and more room for my thumb Also drilled/tapped the base of frame 6-32 to add a third screw to the stock which now makes it rock-solid. Once that was all done, I gave it a few coats of bedliner spray to match rest of stock:
    m_Custom Crosman Stock 013.jpgm_Custom Crosman Stock 012.jpgm_Custom Crosman Stock 007.jpgm_Custom Crosman Stock 017.jpg

    Forearm with three magnets installed:
    m_Custom Crosman Stock 008.jpgm_Custom Crosman Stock 011.jpg

    After all that work, a perfect fit!
    m_Custom Crosman Stock 020.jpg

    And finally, the fruits of my labor...
    m_custom stock 009.jpgm_custom stock 001.jpgm_custom stock 003.jpg

    Hope you enjoyed the transformation, and possibly gave you some ideas to try in the process!
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  3. #3
    Senior Member Doc Sharptail's Avatar
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    That's some pretty original thinking there with the fore-arm magnets.
    I hope you can get the performance you are after out of that shortened disco tube.

    I've been considering a build based off the P-rod system for quite a while now. I'd probably want to go with the factory hammer system as on my 1701-P, as well as the trigger group...

    I can't seem to find the time to sit and bench with the .177 predators- which is the direction I'm currently leaning toward for a future build. Also have to find the time to adapt the transfer port to the older style transfer port system... so many ideas, and so little time. I should add that the P-rod breech is what I'd like to use as well.

    Looking forward to further progress reports.

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  4. #4
    Senior Member sholo's Avatar
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    Quote Originally Posted by Doc Sharptail View Post
    I hope you can get the performance you are after out of that shortened disco tube.
    Me too!

    Tube will be 4" (+/-) shorter than stock which should leave me an air reservoir of 106.6 cc - 21% less than stock , but still 64% more than a 2260 tube.

    I'm not smart enough to figure it out offhand, but Bob's grouse gun http://www.airgunhome.com/agforum/vi...er=asc&start=0 is getting 15 shots @ 20 fpe using a 2260 tube, so I'm hoping (?) to get roughly the same amount of shots (if not more) with the shortened tube, but @ 25 fpe (15.89 JSB @ 850 fps). We'll see once I start testing...

    If all else fails and I can't reach that goal, I will still have enough room in front of the forearm to mount a regulated 13 ci bottle, but having said that, I would like to leave this gun as an non-regulated PCP if possible, both for looks and weight. As I said earlier though - we'll see....


    Also have to find the time to adapt the transfer port to the older style transfer port system... I should add that the P-rod breech is what I'd like to use as well.
    Forgive me for not understanding but, how would that work? The P-rod TP sleeve is longer...or were planning on a poly port?

    If you want to play around with different TP sizes, I have a couple extra P-rod TP sleeves (free to a good home...) that would work in your breech and you could just drill them out to whatever size you desire...just a thought!
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

  5. #5
    Senior Member Doc Sharptail's Avatar
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    Quote Originally Posted by sholo View Post



    Forgive me for not understanding but, how would that work? The P-rod TP sleeve is longer...or were planning on a poly port?

    If you want to play around with different TP sizes, I have a couple extra P-rod TP sleeves (free to a good home...) that would work in your breech and you could just drill them out to whatever size you desire...just a thought!
    I have a few older XX bbls on hand here to play around with~ they have the old style conical inlet for the t.p... First tests will be based off my 1701-P which was designed around a milled flat port inlet.
    The 1701-P t.p. does work with the old style bbls, even though it's a bit longish. I may be able to come up with a replacement t.p. tube sleeve from some s.s. tubing that's laying around not being used.

    I was looking at the posts on the other forum about the m-rod rifle, and it's the same breech as the 1701-P- right down to the 3000 psi max laser etching...

    Like I said, it's just a simple matter of finding the time...

    I did run some jsb heavies through that .177 bbl while I had it on the pistol, and it was surprisingly loud.
    It's possible I'm much closer to a grouse and squirrel head sniper than I realize.

    I may take you up on that long standing offer, early in the new year. I'll p.m. later....

    Regards,

    Doc Sharptail
    "Ain't No Half Way"

    -S.R.V.

  6. #6
    Senior Member sholo's Avatar
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    Ahhh......I smell what you're cooking now!... Looking forward to seeing that project and your results.

    Like I said, it's just a simple matter of finding the time...
    Ya, ok...good luck with that! If you're anything like me regarding "finding the time", it can be quite the elusive lil' bugger!
    Todd

    Don't sweat the petty things, and don't pet the sweatty things!

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