UZI Talk Forums
+ Reply to Thread
Results 1 to 3 of 3

Thread: SA trunnions

  1. #1
    Registered User
    Join Date
    Mar 2021
    Location
    West coast
    Posts
    24

    SA trunnions

    Ordered a trunnion and specified that I wanted an SA, not a FA trunnion.
    Got it and checked dimensions against a GM semi mini barrel I have.
    There's no way it's going together as-is. The SA trunnion is several sizes too small on the I.D.
    I have a demiled front piece (obviously from a surplus IDF UZI) that I got for the sights and notice that the trunnion I.D.s are the same as the GM barrel. Just to be clear, the GM barrel does have the reduced O.D. at the chamber end to slip into the SA feed ramp.
    Further adding to my confusion is that the demil trunnion does not have the cuts for the FA bolt 'feet'.
    I've read everything I could find on the forum regarding semi mini builds but don't see anything related to barrel fit in the trunnion.
    Anybody shed any light on what I have or am looking at?

    Picking up center(s) and boring to the correct dimensions is easy once I'm sure I know what the correct dimensions are.

    https://ibb.co/mB5Jtvc
    https://ibb.co/XxDq3yR

  2. #2
    Registered User
    Join Date
    Sep 2004
    Posts
    663
    To prevent someone dropping in an unmodified short FA bbl into a full size semi auto UZI rifle, IMI reduced the diameter of the bbl and trunnion as well as the reduction at the chamber end to fit into the restrictor ring. You apparently received a reduced diameter semi auto spec full size UZI trunnion that was machined to look like a mini.

    When Action Arms imported the mini, IMI added the restrictor ring feed ramp but left the trunnion diameter the same as on the FA, they just didn't mill in the clearance for the bolt feet. Full size UZI trunnions also lack these cuts as they don't need them. Your bbl is a proper semi auto spec mini bbl.

    Easiest way to tell if a trunnion is a mini or not is look at the top. IMI mini trunnions are skeletonized to reduce weight, if the top of your OEM trunnion is solid you have one from/for a full size gun, not a mini. That is the spec your new one needs to be.

  3. #3
    Registered User
    Join Date
    Mar 2021
    Location
    West coast
    Posts
    24
    The trunnion that's attached to my "demiled front sight assy" is definitely for an FA UZI.
    The trunnion I'll be using came from US Barrel Shrouds. It was solid top and bottom until I skeletonized it.
    I'll leave the reduced I.D.s so that only an SA barrel will fit. Thanks for clearing up the details.

    https://ibb.co/hdqKC9m

+ Reply to Thread

Posting Permissions

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


Please consider becoming an UZI Talk Supporter.