Need advice on a project

[John A.]

No problem.

The Car15 flash hider is what made me think about this, with the exception of a threaded end so I can attach my can or a 9mm flash hider.

After looking around online, there are a lot of fake silencers and barrel extensions and such, but ironically, I must be the first person to ever think of making them look like an actual barrel instead of something else.

But like I said, such a long through-bore is my main concern.

I have plenty of room on my lathe to do it adding in the spindle, but I'm not positive I can keep the tolerances tight enough.

I did email the guy you linked and asked. Worse thing he can do is say no or scare me with his shop fee's LOL

 

[Djcala]

Never know time tough right now. Dont know till ya ask 50/50 shot joy or a backhand. I think its a cool idea. Forgive me i gotta look for tour of duty cd now

 

[John A.]

I had considered starting with a 3/4" steel rod stock and boring the through hole, but needing about 9" removed, didn't think that I could pull it off on my lathe being so deep. Even with going at both ends and meeting in the middle. That's a lot of metal to remove.

I talked to my buddy Nate and he was able to source some very thick wall 4130 pipe that is near perfect for what I need (OD and ID both). I'll have to open up the bore a little, but should be fine with that because I just have to shave a little more out of it.

After thinking about this pretty heavily the last few days, I think I can pull off.

If all goes well enough, I may even turn the OD down to ~.625 to reduce weight some and give it more of a factory pencil barrel look. And if I can remove a half a pound of weight, why wouldn't I?

I may even give it a heatsink look reminiscent of the old Tommy guns. Don't know yet. It's pretty much a blank slate at this point.

 

[John A.]

Got the piece of 4130 today.

Machining is about 90% complete. The only thing I have left to do is the internal 18mm thread to attach to the pistol barrel.

Then drill, pin, weld and refinish the barrel.

The bulk of the machining is done (thankfully). Lots of real tight tolerances to have to deal with.



Muzzle end while on the lathe turning it down for the male 1/2-28 threads so I can attach my can later.





Here's the internal cuts that will be necessary for extension to slide over the pistol barrel and for the where the 18mm threading will attach to the barrel. Since the pistol barrel muzzle protrudes as much, I had to countersink a fairly long hole for clearance.




And a couple of pics to show essentially what I've been blabbering on about.

 

[John A.]

It would be no problem at all using it as a simple barrel extension as is. That is easy.

My biggest hurdle is keeping everything straight. Internal holes, threading, cutting down the exterior and threading.

The length isn't doing me any favors either because the longer it is, the more a slight variance is going to be evident. And also why I'm keeping everything really close to the chuck while I'm working on it to reduce that as much as possible.

I changed the gears in my lathe this morning so I could make the 1mm internal thread and made three passes with the internal threading cutter, but the wall is really thin in that area and out of an abundance of caution so I don't poke through the side if I goof up and go too deep, I am going to finish it with a 18x1mm tap by hand after I buy one.

Now that the single point cut is made, should guide the tap as well if I just finished it on the machine without too much problem.

Once I get the machining done, if I think its' too thin in that area, I'll make a sleeve or collar to go around it to reinforce it and tig it.

 

[John A.]

Been really busy with my family the last few days and haven't had any extra time to work on this.

I machined some of the exterior surface this morning even though most of the grooves will be hidden (recessed) back underneath of the handguard.

I mostly did the exterior work to reduce some of the weight because it's unnecessary, but machined in some grooves as a throwback to the old Thompson "heat sink" fins.

Also, the full auto scorpion has a removable heat sink that they call the "barrel cooler" that looks similar. I also reprofiled the last 3 inches of the barrel and turned it down thinner, to match the OD of the scorpion carbine pencil barrel better to give it more of a factory look.

I will be using Norrells Moly socom black firearm finish on the barrel and extension after I pin and weld it, but I used some cold blue on the raw metal that will be hiding underneath of there to protect it in case of future abrasions in the finish.

 

[Djcala]

The resident mad scientist doin work ! Applaud your skills. We all have common interest for a thousand diff reasons. I like your taking what YOU want and making it your own. Kudos

 

[John A.]

That's very kind of you.

Though most anyone could run circles around me on metal working machines.
I feel like I've accomplished something when parts aren't shattering and flying all over the place.

I just want everyone to be able to enjoy the gun more. It's already a crowd favorite, but having an adjustable stock will take it over the top.

I'm not going to lie, I would've probably bought a barrel extension over making one, but what I needed for this particular gun simply didn't exist.

 

[CaddmannQ]

. . .
I feel like I've accomplished something when parts aren't shattering and flying all over the place.

. . .

I'm a member of that club too and though I have worn eyeglasses since the age of 7, I never bothered to more more until recently.

Nowadays if I pick up a grinder or fire up the bench grinder I reach for the face shield. I have launched as many parts as you brother and I know that someday I will blow up a grinding wheel.

My eyesight would not be improved by that, nor would be my looks.

I am in the borrowed-time club with regards to quite a number of activities, where I now simply do not participate without exorbitant safety equipment.

Motorcycles, skateboards and airplanes would all fall under that (no pun intended) and I do wear the gear.

Putting up a fence in my backyard the other day, I needed a hat, and I instinctively grabbed for my hard hat.

I am totally proud of myself.

But I shouldn't be because I am a total fool in these respects and I have only escaped Serious injury for many years due to Pure dumb luck and quick reflexes.

And at my age I ain't that quick anymore, and my luck is probably running out.

 

[Pawpaw]

That reminded me of an incident that happened while I was still on active duty.

I was leading an Electronics Installation team in the SAC underground at Offutt AFB. One of the things we had to do was make holes for cable access in the false floor tiles under some 19" equipment cabinets we had installed. We were going to do it with a hole saw and a Porter-Cable industrial grade 1/2" drill.

At the safety briefing, it got a chuckle when I held up the drill and told them we called it the "Widow Maker". I explained that if the bit stops the drill has so much torque that it will spin and you can't stop it. Years before, I had personally been thrown off the top of a ladder by one.

I showed them to stand with their feet wide apart, because it will break a leg like a twig. I also emphasised that they would ALWAYS wear eye protection, gloves, and their hard hat while drilling in those cabinets.

A couple of days later, all the guys came out of the room where they were working. One young man looked white as a sheet. Another was carrying the drill in one hand and the side handle in the other. Still attached to the handle was a big chunk of the gear housing. When they dropped the drill on my work table, the chuck fell off. The shaft had been twisted completely in two.

That young man thanked me profusely for making him wear the safety gear. When the hole saw stopped, the drill literally threw him out of the cabinet. It spun around until the side handle hit the cabinet, which explained the broken housing and the twisted shaft.

I never had any trouble with those guys following safety procedures after that.

 

[John A.]

I was able to order the (oddball) M18x1.0 mm RH tap this evening so I can complete the machining part of the project. I hope that it'll be here around the middle of the week. Which will work out well because I have another little project lined up for the next couple of days.

Anyway, I'm hoping that it all works out well.

As long as the threading I do later this week is straight, I think the rest of it will fall into place as planned.

On a slight change though, instead of so many "heatsink grooves" on the exterior of the barrel extension, I turned down more of the exterior and made a step taper in the profile of it that I think looks better. Especially once the longer carbine handguard is bought and installed later.

By tapering the barrel profile, did remove more weight from what it was in the first place. Right now, the extension is just below 9 ounces in total, which I thought was decent without being "heavy".

And yes, the entire barrel and extension will be cerakoted after the pinning and welding is complete so it'll look better in the end after it's all done. I only put some blue on the metal as an undercoating in case the cerakote is ever scratched badly to make it more resistant to corrosion.

 

[nitesite]

John,

You always amaze me.

Your pal,

Dave

 

[John A.]

LOL

In all fairness, this has been kind of an ornery project. But no one makes what I had in mind or needed for this project, so I made what I needed myself.

Now, if I could just get the hand tap so I can clean the threads up, I am ready to check everything to make sure everything is straight enough so I can complete this.

 

[nitesite]

If anyone could document and accomplish such a conversion it would be you my friend.

 

[John A.]

Those are pretty big shoes to fill. We shall next week though. I'm not one to give up too easily.

Delivery tracking for the 18x1mm tap is scheduled for Tuesday. I got the payment for the uzi barrel now and was able to order the hbi carbine handguard this morning. I'll probably have it next week too. So things are starting to fall into place.

 

[John A.]

Someone must've spurred the pony express horse. I got the hand tap today.

I'm not going to complain about that.

I was able to chase the threads that I did on my lathe to give a cleaner and better contact surface.

It's going to turn out as good as I had hoped.

A few quick snapshots as I was checking everything

1. The extension threads on and shoulders with the barrel that's underneath of there just fine.

Check.

Also, ran a precision guide rod down the bore to bottom out on the face of the bolt to ensure that it will meet the minimum 16" limit.

Check.





Right at 16.1"

No disputing that the minimum legal length is in accordance with the law



And checking internal tolerances to make sure I won't have any problems with concentricity if I use my can on it.



And checking at the exit end of the can for good measure



I ordered the hbi carbine handguard this morning now that guy finally paid for that barrel that's been put in the back of the safe for so long. Should be here early next week.

I don't think I can do the blind pin and tig weld the barrel until I get the handguard mounts in place because the mount slides over the end of the existing barrel so I won't be able to complete the project until the mount itself is installed.

So for the meantime, I plan to take this up to the range and continue to shoot it as a pistol and test fire a couple of shots to see how it performs.

 

[John A.]

My buddy welded the extension this morning. (He welds so much better than I do).

I still need to install the front sight and refinish the entire barrel with Norrells Socom black Moly, but I'm so glad that I did this. It was a challenging project. But one that I'm glad that I did.

One of the most important pics of the project. The compliance pin.



Then the required weld over the pin, to which I even surpassed regs and had him weld a portion of the extension to the barrel in that area too

And for size reference:



After test firing and making sure all is fine, here's the pinned extension after the entire barrel has been refinished with Norrells Moly.