UZI Talk Forums
+ Reply to Thread
Results 1 to 4 of 4

Thread: FNC Headspace question

  1. #1
    Registered User
    Join Date
    Mar 2018
    Posts
    2

    FNC Headspace question

    Guys-
    I'm hoping someone can help me out. I bought a set of Clymer .223 Go/Nogo and 5.56 Max/Min headspace gauges. They work great on several AR's, an Austrian AUG, and an IMI Galil.

    Why don't they work on FNC's? I tried this on three different FNC's, including one I have taken out and fired with no issues. In all three cases, the bolt refuses to close on the Go gauges. Is it a difference between CIP and SAAMI chamber dimensions? I asked PACO recently and hope to hear back but I am at a loss.

    Does anyone have any specifics on FNC chamber dimensions? Maybe someone has drawings of the upper and lower receiver with dimensions?

    Also- Is there a reason Howco's seem to be more expensive than Steyr or Gunsouth FNC's?


  2. #2
    Registered User
    Join Date
    Dec 2005
    Posts
    466
    Here you go

    mini 37.89mm
    Maxi 38.11
    reject 38.15mm











  3. #3
    Registered User
    Join Date
    Mar 2018
    Posts
    2
    I wanted to report back what I have learned to the group and ask for more help.

    Does anyone have a true Belgian MIN headspace gauge I could buy or even rent? I have determined they are VERY different from the gauges on the US market.

    After this thread started I bought a 5.56 min gauge built to CIP specs made by a well known US gauge company. Two of the three FNC's failed to close on the CIP gauge EVEN THOUGH IT IS SHORTER. Here are the dimensions of all the gauges I know about so far:

    Dimensions for Gauges available on American market

    SAAMI

    .223 Go 1.4636" = 37.17544mm

    .223 No Go 1.4696" = 37.32784mm

    .223 Field 1.4736" = 37.42944mm- Interesting point- this is the same dimension as the Clymer 5.56 MAX gauge

    CIP

    .223 Min 1.4634" = 37.17036mm

    .223 Max 1.4673" =37.26942mm



    Dimensions for Belgian gauges

    Min 37.89mm= 1.4917"

    Max 38.15mm=1.5019"

    The Belgian MIN gauge length is .72mm or .028" longer than the CIP min gauge. This is a substantial difference in length between the two.

    Are the Belgian gauge dimensions listed as the overall length of the gauge as opposed to a measurement to a point on the case shoulder as American gauges are? This would explain the difference in length and why they refuse to close.
    Last edited by planemarty; 07-30-2018 at 12:26 PM. Reason: adding details

  4. #4
    Registered User
    Join Date
    Dec 2005
    Posts
    466
    drop me a mail...

+ 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.