Craftsman 441
CGN Regular
- Location
- Wainwright
So I've been working on making a C8 clone and a C8A3/C8HB clone.
I was profiling the 16" HBAR on the lathe and now I'm at the point where I have to add the sleeve.
There are a few pictures online, and a good number of threads out there (especially on airsoft forums) about the sleeve, what it's for, etc. But very little containing actual dimensions.
I checked the CGCM (Cdn Gov't Catalogue of Materials) and found this:
It confirms a few things I had figured-out on my own: The front diameter (0.862") is for a 22mm NATO standard bayonet ring with a 0.004" clearance; And the rear diameter for the barrel clamp (0.846") for an M203A1 is the same diameter as a C7 behind the front handguard cap with that same 0.004" working clearance. The center diameter isn't too much of a surprise, since I figure the sleeve starts life as a piece of 1" bar stock, but now I have a number to put my finger on.
Overall length doesn't give any clue to the lengths of the sections. I'm going to assume the sleeve on a barrel that is 1.5" longer than the 14.5" standard will have a shoulder at least 1.5" back for the bayonet. The rear shoulder should be the same distance from the back of the barrel as the rear of the gas block journal on a 20" barrel, since that is waht the M203A1 mount was designed to fit to. For a 16" barrel, that should be 2.5" back. I assume the rear of the sleeve is in the same spot as the shoulder of the 'M203 cut' on M4 barrels.
What really surprises me is the 0.624" bore. That suggests that the barrel is turned to 0.625" (5/8") at the end to ensure a proper fit when the sleeve gets pressed on. Either that, or the sleeves are re-bored after delivery to the contractor and fitted to the barrel. The latter case may be asinine, but dumber things happen in defense procurement.
Anyway, I wanted to share this info and see if anyone else could confirm my thoughts, add some details and pictures.
I'd also like to know where the 'Simon' name came from.
I was profiling the 16" HBAR on the lathe and now I'm at the point where I have to add the sleeve.
There are a few pictures online, and a good number of threads out there (especially on airsoft forums) about the sleeve, what it's for, etc. But very little containing actual dimensions.
I checked the CGCM (Cdn Gov't Catalogue of Materials) and found this:
It confirms a few things I had figured-out on my own: The front diameter (0.862") is for a 22mm NATO standard bayonet ring with a 0.004" clearance; And the rear diameter for the barrel clamp (0.846") for an M203A1 is the same diameter as a C7 behind the front handguard cap with that same 0.004" working clearance. The center diameter isn't too much of a surprise, since I figure the sleeve starts life as a piece of 1" bar stock, but now I have a number to put my finger on.
Overall length doesn't give any clue to the lengths of the sections. I'm going to assume the sleeve on a barrel that is 1.5" longer than the 14.5" standard will have a shoulder at least 1.5" back for the bayonet. The rear shoulder should be the same distance from the back of the barrel as the rear of the gas block journal on a 20" barrel, since that is waht the M203A1 mount was designed to fit to. For a 16" barrel, that should be 2.5" back. I assume the rear of the sleeve is in the same spot as the shoulder of the 'M203 cut' on M4 barrels.
What really surprises me is the 0.624" bore. That suggests that the barrel is turned to 0.625" (5/8") at the end to ensure a proper fit when the sleeve gets pressed on. Either that, or the sleeves are re-bored after delivery to the contractor and fitted to the barrel. The latter case may be asinine, but dumber things happen in defense procurement.
Anyway, I wanted to share this info and see if anyone else could confirm my thoughts, add some details and pictures.
I'd also like to know where the 'Simon' name came from.
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