Page 1 of 6 1 2 3 4 5 ... LastLast
Results 1 to 10 of 57

Thread: build your own FN P90

  1. #1
    TRX
    TRX is online now
    Gunco Irregular TRX's Avatar
    Join Date
    Aug 2008
    Location
    Central Arkansas
    Posts
    2,828
    Feedback Score
    3 (100%)

    Default build your own FN P90

    Presented for your amusement:

    I picked up a P90 magazine from CDNN last year, when they were on sale for $19.95. I bought it just to see how it turned the cartridges 90 degrees to present them to the breech. It uses a nifty helical ramp.

    5.7 ammunition is, for some inexplicable reason, dirt cheap now. The "5.7" bullet's published diameters seem to be basically the same as "5.56", so you can use readily-available .223 barrels. You'd have to find a reamer.

    As far as the bolt and breech are concerned, the P90 magazine works just like any other magazine.

    You could easily build a tube gun, something like the SGN-9 or your own design, that would shoot 5.7x28. The P90 uses straight blowback.

    Tube guns tend to range from "industrial" to "fugly" in appearance. If you wanted to make it not quite so industrial looking, you could wrap it in a plastic shell.

    Where would you find a plastic shell? I found this FN P90 airsoft:

    Amazon.com: Well P-90 Laser Red Dot Airsoft Electric: Sports & Outdoors

    It's $26.95, $39 to your door. You could open it up, discard all the airsoft bits, and fabricate some bracketry to wrap it around your tube gun.

    I'm not a fan of the P90's looks, though I admit it's rather striking. But as a lefty, the fact that it ejects down instead of my face or left armpit is a strong plus. Also, "cheap is a quality overcoming many faults."
    Attached Images Attached Images

  2. #2
    Gunco Veteran Viper Dude's Avatar
    Join Date
    Feb 2005
    Posts
    1,686
    Feedback Score
    0

    Default

    Cute idea !!!
    Wonder what is the diameter of the 5.7mm case head ?? Same as 9x19mm ammo ie 10mm ???

    The FN P90 seems to have a square receiver. Maybe a MAC bolt ???

    VD

  3. #3
    Administrator pirate56's Avatar
    Join Date
    Dec 2004
    Posts
    4,996
    Feedback Score
    31 (100%)

    Default

    the p90 uses DELAYED blow back, not straight blow back, there is a BIG difference!!

  4. #4
    Happy Camper hcpookie's Avatar
    Join Date
    Feb 2004
    Location
    Colorado Springs
    Posts
    7,702
    Feedback Score
    3 (100%)

    Default

    The 5.7 cartridge uses the same size shell holder as the .25 ACP.

    The internals for the AR-57 may be a good starting point.
    Gunco Member #10

    http://pookieweb.net


    The "original" Boltcutter Rivet Squeezers:
    http://pookieweb.net/AK/rivet/boltcutters/boltcutter.htm


    Project Pink - the Pink and Blue AK-74:
    http://pookieweb.net/pink/pink.htm

  5. #5
    TRX
    TRX is online now
    Gunco Irregular TRX's Avatar
    Join Date
    Aug 2008
    Location
    Central Arkansas
    Posts
    2,828
    Feedback Score
    3 (100%)

    Default

    Hmm, interesting. The sites I hit early on all said straight blowback. Some others say short recoil. Others say both, which is par for the course... if FN Herstal's web site says anything, darned if I can find it.

    Looking at the ballistics of the cartridge, I don't see any problem with running 5x7x28 in blowback mode, though.

  6. #6
    TRX
    TRX is online now
    Gunco Irregular TRX's Avatar
    Join Date
    Aug 2008
    Location
    Central Arkansas
    Posts
    2,828
    Feedback Score
    3 (100%)

    Default

    There's a guy on YouTube who stuffed a Ruger 10/22 inside a P90 airsoft shell. Among other things that seem to have vanished with the new "improved" YouTube is the "link to this" URL they used to have, unless it's another casualty of their broken HTML vs. Konqueror.

    Anyway, paste "Building instructions Ruger 10/22 FN P90 Replica Video 3" into YouTube's search bar and you'll see it. Most of the work was to handle the 10/22's side ejection and bottom magazine. None of this is relevant to a tube gun, but it shows the inside of one of the airsoft shells.

  7. #7
    aka: SDK1968 dutigaf's Avatar
    Join Date
    May 2006
    Posts
    4,104
    Feedback Score
    14 (100%)

    Default

    i luv this cartridge in my ar set up and it works just fine....
    say what you mean & mean what you say


  8. #8
    tired of idiots vz58's Avatar
    Join Date
    Sep 2006
    Location
    central NC
    Posts
    2,276
    Feedback Score
    25 (100%)

    Default

    Pirate, I have read that it is delayed blowback but I took a buddies apart and I saw nothing to indicate that. A light bolt and 2 springs....

  9. #9
    Gunco Regular eyegun's Avatar
    Join Date
    Mar 2005
    Posts
    530
    Feedback Score
    4 (100%)

    Default

    I've got a PS90 and a 57 upper.

    If blowback is delayed I can't figure out how they're doing it.

    Looks like straight BB to me which would explain why I get slightly OOB detonations from time to time on my 57 upper (full auto). The 57 upper does have the BC slightly longer to put the buffer under tension but if that's what they're calling delayed BB that's a stretch.

  10. #10
    Gunco Veteran [486]'s Avatar
    Join Date
    Dec 2008
    Location
    MSP area, MN
    Posts
    1,631
    Feedback Score
    0

    Default

    Quote Originally Posted by vz58 View Post
    Pirate, I have read that it is delayed blowback but I took a buddies apart and I saw nothing to indicate that. A light bolt and 2 springs....
    Looking at the bolt on one at the gunstore it has a sprung counterweight that looks like it is to hold the bolt back for a bit longer, delaying the return of the bolt into battery. Maybe that's the delayed part to it...

Page 1 of 6 1 2 3 4 5 ... LastLast

Search tags for this page

There are currently no search engine referrals.
Click on a term to search our site for related topics.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •