Monday, November 12, 2012

Carbon Fiber Shroud for the S&W 78G Part 1

After seeing Nick's recent Smith & Wesson 78G post, it gave me an idea to try on mine.  Want to increase the barrel length to gain velocity, but the extended soda straw look leaves much to be desired.  Thought about covering the extended barrel with a shroud.  The shroud will simply cover the barrel.  Note:  There is absolutely, positively no possibility of sound suppression as the barrel will run all the way through the shroud from end to end.  None.  The muzzle will be visible at the front end of the shroud.

With that out of the way, I hit my scrap box and found a carbon fiber tube approximately 1.125" OD and just shy of 7" long.

It was a bit too shiny, so it was scuffed with a scotch brite pad to produce a matte finish.

Need a couple aluminum end caps so it can be attached to the airgun.  Faced some 1.5" 6061 aluminum rod.

Turned down to match the OD of the carbon tube, then stepped the end to fit into the tube's ID.

This is a good time to spot and through drill.

Used a 1/4" bit.

This is the clearance hole for the .22 cal pellet.

The rearmost end cap is up first.  Drilled partially through with a 7/16" bit--this will allow a Crosman 22XX barrel to pass through.

Parted off.

Cleaned up the face and beveled the edge.

On to the front cap.  Again, turned to match the OD of the carbon tube and stepped for the ID.   Drilled partially through with a 25/64" bit.

Followed by a 7/16"-20 tap.  Ran the thread right to the bottom of the hole.

Parted off the front cap.

Faced and beveled.

Chucked the rear cap in the Taig and cut two o-ring grooves.

This is a snug press fit over the barrel.

Here's the thread on the inside of the front cap.  Deburred all the edges and did some test fitting.

So, there's no thread accessible from the outside.  The barrel has to pass completely through so the muzzle can thread into the front cap.

The double o-rings will isolate the shroud and keep it from rattling against the barrel.

 Painted the end caps then glued them into the carbon with J-B Quik epoxy.

Next up is machining a Crosman 2260 barrel to fit the shroud and Smith & Wesson air pistol.

More in a few days.