
Originally Posted by
wild_wild_wes
My gunsmith said the usual gap runs about .030", but mine is nearly at .060"....so there is some variability on this, depending on manufacturer.
A few years ago I put a PRI flip up (clamp style) on a DPMS M4 cut barrel and it was .058" (IIRC). I think there was some variables at work here. Possibly the handguard cap edge was too far back on the barrel (I didn't measure it to the barrel extension), or the PRI gas port was machined too far forward in the gas block and/or the gas port was too far forward on the barrel. Or it was a combination of the 'stacking' tolerances everything being on the edges of the allowable tolerances.
Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
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