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Are all the ports antipodal to another?

I can't drill anything by hand without hitting whatever is on the other side.

doubloon wrote:Are all the ports antipodal to another?

I can't drill anything by hand without hitting whatever is on the other side.

After looking up Antipoidal ha ha, yes they are but I just drill off one side at a time, that siad your issue with going through is easy to fix, just work out the depth you need to go to and wrap a lod of tape around the drill bit to act as a depth indicator. if you need a physical stop use a bit of wooden dowel cut to length on the drill bit.

Cheers

I slide a piece of wooden dowel rod down the barrel when drilling out gas ports. Keeps me from hitting the other side when I break through.

cdakers wrote:I slide a piece of wooden dowel rod down the barrel when drilling out gas ports. Keeps me from hitting the other side when I break through.

Great idea

cdakers wrote:I slide a piece of wooden dowel rod down the barrel when drilling out gas ports. Keeps me from hitting the other side when I break through.

Yes it is.

Used backers before but it didn't occur to me to insert a backer into the tube.

If you wish to increase the velocity drop better try porting like H&K.Lots of ports over a short distance causes a gas dump not a slow bleed like a long string of ports.This has been proven to work best according to history .So your first row of ports would be starting at 3.500" if you use 3.00" shells.This allows for the pedals of the shell to open and not block the ports.Study this picture and allow 1 or more diameters between holes.I would start w/ .500 length of ports and test if you hear the sonic boom.Add or subtract to find the best number of ports.I would take some time to debur and polish to eliminate the plastic shavings.A bonus to porting very close to the chamber is less ports are needed and the pressure and heat help clear the ports.



PS: Most drill presses have a drill depth stop.I use mine for drilling and tapping when depth is critical.A drill bit of known diameter can be used to set the depth.

I wish everyone health and prosperity in this new year.

-CL

Capt. Link. wrote:So your first row of ports would be starting at 3.500" if you use 3.00" shells.This allows for the pedals of the shell to open and not block the ports.

A fired 3 inch shell is 3 inches long. The ports dont need to start 3.5" down.

fishman wrote:

Capt. Link. wrote:So your first row of ports would be starting at 3.500" if you use 3.00" shells.This allows for posting.php?mode=quote&f=10&t=139022&p=949673#the pedals of the shell to open and not block the ports.

A fired 3 inch shell is 3 inches long. The ports dont need to start 3.5" down.

I've honestly have never measured a spent or live .410 shell. I prefer the shorter shells and would need to allow for the shell to open if I was porting for it........The idea being don't block the ports.......

-CL

Capt. Link. wrote:...
I've honestly have never measured a spent or live .410 shell. I prefer the shorter shells and would need to allow for the shell to open if I was porting for it........The idea being don't block the ports.......

-CL

I believe all shell lengths as quoted are the length of the un-crimped shell.

It's the length of the unfolded hull that is important for chamber clearance, you don't want the hull unfolding into the bore.

Well done.
I used a Shotgun barrel porting jig. Like the "U port it."

https://www.brownells.com/gunsmith-tool ... 15478.aspx

Came with bushings. Used it for customer work on shortbarrel Shotgun and was great on porting 12 ga for integrals. Spacing on it was great to. Shortstory the chamber I skipped every other hole. A spare dril in a bushing allowed you to stay on track for the remainder of the barrel for longer series.

Gunny

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