Making choke tubes out of D2 tool steel?

[roverboy]

I wondered how D2 would be for making choke tubes? It's a good grade of steel. Definitely not softer like cold rolled. I've made some out of D2 and they seem to be holding up fine. I mean think about it, the old guns that had fixed chokes, we're made out of 4140 or something similar. Thanks

[fast ronnie]

Are you heat treating those or using them in normalized condition? D2 can be treated to 62 rc as normal process, but hardness and toughness are a trade off. I would think that 4340 heat treated to somewhere around 40 rc would be a better choice.
4340 is my go-to steel for high strength high stress applications. D2 is a cutting steel used in stamping and cutting dies. H13 would possibly be another good steel as it will take an extreme amount of punishment, even though it is actually designed for high temp, high strength uses such as forging. Just some food for thought, though I wonder if the expense would be justified by the results.
That would depend on the reasons for doing this.

Ron

[roverboy]

No, I've not heat treated them. Sometimes D2 will "shrink" a little. Also after treating it is super hard to machine. I fully understand what your saying. I'm just using scrap pieces that are in the scrap bin at work.

[Reverend Recoil]

Do you think seamless carbon steel hydraulic tubing might work for a shotgun choke tube?

[fast ronnie]

If you use d2 at work, you already know the properties. As long as you are not heat treating, I think it would be OK. It is pretty tough in normalized. It has a lot of chrome in it. That is what makes it a little hard to machine.

[roverboy]

If you use d2 at work, you already know the properties. As long as you are not heat treating, I think it would be OK. It is pretty tough in normalized. It has a lot of chrome in it. That is what makes it a little hard to machine.

Yeah, its good quality steel. It would be awesome if it was heat treated though. Like I said, I've not had any problems yet. I know its probably at least as hard and durable as a normal barrel. We use it for die parts.

[roverboy]

Do you think seamless carbon steel hydraulic tubing might work for a shotgun choke tube?

It might but, really its hard to know what grade the tubing would be. What inside diameter is the tubing?

[roverboy]

Here's a few I made. L to R, .655, .665, ,665, .640 constrictions.220686

[Drm50]

I've only made one. I bored it and turned it down out of a shaft from a electric motor. It's about
41/2" long at .638", I was going for .635". Anyway it was my first and when I tested it I was
shooting a doughnut pattern. After deciding wad was blowing pattern I drilled a hole pattern and
repolished. That solved the problem but it won't shoot anything bigger than#6s worth a hoot. The
smaller the shot the better it shoots. I have retired from choke making.

[fast ronnie]

It might but, really its hard to know what grade the tubing would be. What inside diameter is the tubing?

I would think hydraulic tubing would be too soft.

[john.k]

Hydraulic tubing is pretty hard and tough from cold drawing,but yield strength might be doubtful.........the problem with screwin chokes is,.... if they expand and jam in the gun......then you ve lost more than a bit of lathework.

[W.R.Buchanan]

Typically Choke tubes are made from 17-4 SS at H1000. D2 is kind of over kill to the max. If you heat treated them, they would last forever shooting steel shot on a daily basis for the rest of your life, and then some. Any High Carbon tool steel would perform similarly.

As far as shrinkage is concerned as long as your threads are within the correct pitch diameter for that thread heat treating won't change them enough to make a difference. Just run them on the lower end of the PD. IE: looser.

However nothing wrong with D2 otherwise, it is certainly up to the task at hand.

Randy

[longbow]

I've just received my Carlson's choke tube adapter for silver soldering to a turned muzzle along with two choke tubes ~ I/C and blank. The blank tube will get bored to around 0.710" or maybe a bit larger then rifled to 1:72" twist with about 0.010" deep rifling with the intent of being a modern Paradox like rifling system.

I was quite surprised by how thin the choke tubes are! Like really thin!

I had originally planned to make a system similar to the old Packmyr Power Pac then make rifled tubes but it was a bit much work so I took the easy route. However, now that I see the choke tubes I have to wonder.

I think your D2 is a good idea and I like your extended tubes. I may need more length than the blank tube I bought has... although I guess if the slug is going to strip it will strip whether short tube or long tube. Nonetheless, I like your long tubes. I may wind up making a long tube then rifling. We'll see.

With the thin walls I'd feel happier with a good material like D2 but that's just me.

Longbow

[W.R.Buchanan]

I might add that lots of Carlson's Choke Tubes are turned on machines I personally built for them back in the mid 90's. They were Omniturn Slant 75 machines which I invented.

They looked like this one except they were Cobalt Blue. This one was made specifically for me,,, by me!

D2 when heat treated to 60+ Rc is about 280,000 psi. 17-4 at h1000 is about 180,000 psi. both are more than up to what you are trying to do.

Randy

[roverboy]

I might add that lots of Carlson's Choke Tubes are turned on machines I personally built for them back in the mid 90's. They were Omniturn Slant 75 machines which I invented.

They looked like this one except they were Cobalt Blue. This one was made specifically for me,,, by me!

D2 when heat treated to 60+ Rc is about 280,000 psi. 17-4 at h1000 is about 180,000 psi. both are more than up to what you are trying to do.

Randy
That CNC lathe is pretty cool. I've not ran one of them in years. Making a choke or anything else on a manual machine takes some time too.