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Gunsmithing FN Five Seven barrel threading, got it...

jonaddis84

Gunny Sergeant
Commercial Supporter
Full Member
Minuteman
Jan 27, 2009
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Toledo, OH
www.area419.com
Buddy just picked one up and will want it threaded. Ive looked at these barrels before and wondered how the hell Tornado threads them. Anyone have details?
 
Re: Anyone threaded a Five Seven yet?

Check out the Five-Seven Forums for info regarding Tornado Technologies.

It's a larger and more subject-specific resource, and the info is excellent.
 
Re: Anyone threaded a Five Seven yet?

Got the gun in and took some measurements.

OD of barrel is 0.4124, bore seems to be about 0.226 in the grooves.

Id rather stay away from metric threads if I can. Im thinking 5/16x48 to thread it so I keep the threads shallow.

Do you think that leaves the area between the bore and thread root too thin? 3/8 threads would not give me much of a shoulder to locate the adapter.
 
Re: Anyone threaded a Five Seven yet?

I looked at tornado's site again, they thread them 10mmx1, but there is no shoulder. This must be for a dedicated 5.7 can that locates on the muzzle or something?

Im planning on making an extension that goes from 5/16 up to 1/2, and Ill probably have to mill some flats on it so it can be tightened and removed from the barrel for disassembly. It will also have to have the groove turned into it for the snap ring that captures the spring.
 
Re: Anyone threaded a Five Seven yet?

The way I recommend is the barrel is indicated in and a thin truing cut is made on the barrel then a sleeve is silver soldered on then trued and threaded 1/2X28 with a torque shoulder left for the suppressor.This is a invisible permanent and accurate way to do this job and allows the use of standard threaded suppressors without the need for "adapters"
 
Re: Anyone threaded a Five Seven yet?

Sounds good, but if Im understanding this correctly, the barrel is then permanently stuck in the slide right?
 
Re: Anyone threaded a Five Seven yet?

what tornado tech does is weld a piece on the end of the barrel and then thread it. if you want a picture please pm me and ill send you a picture of mine. it is threaded at 10mmX1 and you get a 10mmX1 to 1/2X28 adapter.
 
Re: 5.7 bbl dimensions, what thread size?

here is a few pictures.

the second picture shows the cut line.

IMG_1662.jpg

IMG_1663.jpg

IMG_1664.jpg

IMG_1665.jpg
 
Re: Anyone threaded a Five Seven yet?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jonaddis84</div><div class="ubbcode-body">Sounds good, but if Im understanding this correctly, the barrel is then permanently stuck in the slide right? </div></div>
There is not many times in the the life of a rifle that it needs to be stripped to that level and if it needs to be done the silver solder can be melted the threaded piece removed and a new piece remade for the rifle.I have no problem with Tornado Techs System in fact I know they do great work and would recommend them. I just don't like a adapter for a suppressor its a double whammy on threads coming loose and possible misalignment of the can plus I am a accuracy nut.Most of my clients agree this is a good thing.
 
Re: Anyone threaded a Five Seven yet?

there is a suppressor with the 10mmX1 threads so no need for the adapter i have the adapter for my AR57 as well as the 5.7 pistol.

so in short you don't need the adapter if you are going to use the suppressor on the 5.7 pistol only.

here is the link for the 5.7 suppressor
http://www.gem-tech.com/store/pc/SFN-57-2p126.htm
 
Re: Anyone threaded a Five Seven yet?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: P.A.R.</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jonaddis84</div><div class="ubbcode-body">Sounds good, but if Im understanding this correctly, the barrel is then permanently stuck in the slide right? </div></div>
There is not many times in the the life of a rifle that it needs to be stripped to that level and if it needs to be done the silver solder can be melted the threaded piece removed and a new piece remade for the rifle.I have no problem with Tornado Techs System in fact I know they do great work and would recommend them. I just don't like a adapter for a suppressor its a double whammy on threads coming loose and possible misalignment of the can plus I am a accuracy nut.Most of my clients agree this is a good thing. </div></div>

In the life of a pistol though, you need to remove the barrel to do any kind of cleaning. I like that idea of silver soldering the extension on, but I would not want the 1/2" threads to be part of that extension, it would be similar to the tornado setup, but the adapter would HAVE to locate on the end of the threads since there is no shoulder. And machining a square shoulder on the inside diameter of a 10mm ID is going to be tricky with the tooling I have at my disposal. I dont think I would necessarily trust boring a hole with an endmill...

Guess I can give it a shot and see if it works. Ill put an indicator on there with the can on to make sure its right down the pipe.

I figured the tornado setup was for a dedicated 5.7 can, but this setup is going to be used with a TBAC 22L-1 so it needs to have 1/2 threads.
 
Re: 5.7 bbl dimensions, what thread size?

Got it figured out today, was a PITA, but successful. Tried 3/8-40 threads initially, but the cut for the spring retainer ring had to be too deep that it went through the extension threads. Ended up using 5/16-40 threads instead and I think there is plenty of meat in there.

Its kind of tricky to install the barrel, but not terrible. You basically have to install the barrel without the extension but with the spring and retainer washer installed. Then push the barrel forward and put a block behind the chamber to keep it forward. Thread it on and go. I cut flats for a 3/8 wrench to tighten it, which is completely necessary!

Anyway, incase anyone else has one of these come up in the future...

57thread1.jpg

57thread2.jpg

57thread3.jpg

57thread4.jpg

57thread5.jpg

57thread6.jpg
 
Re: 5.7 bbl dimensions, what thread size?

Good work Jon,

My contact at FN warned me about shooting supersonic with a can, they said its hard on the frame and can reduce the life span of the weapon. Makes sense!

Mark
 
Re: 5.7 bbl dimensions, what thread size?

Yeah, after shooting it I agree! I was getting nailed in the face with blowback debris, and the felt recoil was greatly increased.

I think he is going to handload for it, so he should be able to tone them down a bit so its not so harsh.

The 22L-1 took it like a champ, even though its technically not rated for 5.7, Zach said to keep it under 700*F and it should be fine. I had no doubts in it...
 
Re: 5.7 bbl dimensions, what thread size?

Jon volunteered to be our tester for 5.7 in the 22L-1.

I am not surprised with the blowback-- that's one reason my .22LR pistol host is a Ruger; there is no path from the breech directly to my face.