The Correct Fitting of Moderators

The Correct Fitting of Moderators

The key to fitting a moderator correctly is all in the threading

There are six key aspects to the thread:

  1. The thread MUST finish at the abutment end with a clean thread and not taper out – in practice this means cut on a lathe with a point tool (Not a die-nut) with an slight 1.1-1.7mm undercut at the abutment end
  2. The thread MUST be parellel to the bore – again in practice this means cut on a lathe with a point tool (Not a die-nut)
  3. The thread MUST be concentric to the bore – again in practice this means cut on a lathe with a point tool (Not a die-nut)
  4. The Moderator must be slightly lose on the muzzle thread – in practice just before the mod stops with a nice “clunk” against the abutment the mod should have 2-3mm of “wobble” at the far endIf your moderator is fitted by someone less familiar with the
    specifics of moderator threading,  they are likely to fit a “nice tight” smooth thread –
    unfortunately this results in the moderator aligning with the mod thread/muzzle thread instead of squaring to the abutment face – which is the most accurate
  5. The abutment face MUST be Square to the bore – again in practice this means cut on a lathe
  6. The thread chosen should leave sufficient material between the root of the thread and the bore, so an 1/2″ UNF thread would have a root diameter of circ 11mm – on a 308 (7.62mm) calibre – this gives a barrel thickness of just ~1.6mm!  

And finally

The Back-Bush MUST BE FITTED on moderators where they are supplied/designed for – T8, T4, etc – most reflex (back over the barrel) types