Author Topic: Venting a barrel (Read 1372 times)

Evil Dog · « **on:** July 24, 2004, 05:10:09 AM »

According to the UPS Tracking Number, my 1/3rd scale 6 Pounder barrel from Gray-Star should be arriving next Wednesday. The breech area is supposed to be 3.7" diameter.... with a 1" steel lined bore that would leave a wall thickness of approximately 1.35". Comes the question of just how to vent it. I do like the vent liner such as shown in The More Complete Cannoneer. Should be easy enough to do using a brass bolt. I seriously doubt that I would be making it easily removable though. Instead I would probably epoxy it in place.... removing it would require heating it to release the epoxy and then using an ez-out in the vent hole. As to position, I believe the vent hole should enter the bore approximately 1/8" from the breech plug or base of the bore. Should it be drilled straight down (90 degrees) or at a slight breech to muzzle angle?

Double D · « **Reply #1 on:** July 24, 2004, 10:04:27 AM »

Make it 90 degree. Remember that hot gases are going be blowing out of that hole.

Why do you feel the need to glue the vent permanent?

Evil Dog · « **Reply #2 on:** July 24, 2004, 10:17:59 AM »

Hi Double D..... Ok, will go with the 90 degree vent. The main reason I had in mind for adding epoxy was just to seal the threads. That might be a bit of overkill though. Afterall, I don't glue the breechplug threads on any of my muzzleloading rifles.

Double D · « **Reply #3 on:** July 24, 2004, 11:01:01 AM »

If you look closely at the vent piece in Cannoneer, you will notice the bottom is angled. That is a seat. The hole for the vent is not drilled straight all the way through. The hole has a seat in it also for the vent plug to bottom against.

Cannoneer also says to use high temperature grease on the threads of the vent plug to facilitate future removal.

Evil Dog · « **Reply #4 on:** July 24, 2004, 11:56:13 AM »

Looking at that vent piece again, it appears as though not only is the vent hole in the barrel not completely drilled through it is also counterbored near the surface!!! This allows for 2 seating surfaces. Could be getting into a lot more machining than I am capable of.

Double D · « **Reply #5 on:** July 24, 2004, 12:05:33 PM »

You can do all that machining with a drill bit. Drill a pilot hole all the through. Then drill your minor thread diameter hole almost all the way through leaving the 118 deg angle of the drill as a seat surface in the bottom of the hole. Angle the bottom of the vent to match.

Just drill a relief diameter at the top of the vent. You don't need to seat at the top only at the bottom.

Evil Dog · « **Reply #6 on:** July 24, 2004, 12:24:57 PM »

Ok, you've talked me into it..... make it sound fairly simple. Then there is always the option of drilling everything a bit larger and plugging with a brass bolt threaded all the way through. Then just drill fuze size vent hole.

Double D · « **Reply #7 on:** July 24, 2004, 01:50:22 PM »

You could do that also, just make sure the vent doesn't protrude into the chamber and tear youy cartridges open when you load and hang foil up when you worm.

Ramrod · « **Reply #8 on:** July 24, 2004, 05:02:25 PM »

As a long time black powder shooter, and a soon to be cannoneer, I have just one question. Where do you find brass bolts big enough for liners? I just don't see them on the shelves of my local stores. I would want to have several on hand, so that when I replace the liner I know it will fit. And I think glueing them in is not a good idea, these are just bigger versions of the vent liners used on rifles and shotguns, made to be easily replaced when the hole burns too big.

Evil Dog · « **Reply #9 on:** July 24, 2004, 05:13:24 PM »

Hi Ramrod.... an interesting question as I haven't actually looked for brass bolts yet. Would probably need a minimum of 1/4" diameter with 5/16" being a better choice. Also would be looking for ones that aren't threaded the entire length. I've seen brass "all thread" threaded rods up to 3/8" in brass. If I can't find what I am looking for in brass, there is always stainless steel.