Great find, thanks for posting this!

And they don't consider pinning and welding to be an approved method, yet it's the most common.  A ground off loc-tited set screw is not coming off without some grinding or drilling.  So if the blind pin is considered good, even though the ATF doesn't acknowledge it, then I don't see where the problem with the set screw is.

Wrong
http://i129.photobucket.com/albums/p203/CHRIS65-IL/ATF_Chp2_Rifle_Image1.jpg  and welding isn't even mentioned

And the entire booklet  http://www.atf.gov/firearms/nfa/nfa_handbook/chapter2.pdf

Blind pin/welding IS an ATF approved method.

Tagitytoooo

As a newbie reading this here is what I have taken away.

Both methods if done correctly look fine.
SS requires a heat stop paste ($15) and the SS itself ($ ??)
Blind Pin and weld requires a drill press and welder. (Or pay Adco $30)

If I understood correctly removal consists of:
SS Method:  Reheating FH and twisting off and cleaning treads with wire brush. (Pieces can be reused again)
Blind Pin Method: Most common method I have seen on here involves splitting the FH and removing, but there has been some mention of removing the pin. Wasn't clear exactly how or the reusablity of the removed FH.


So for me sending my barrel to Adco for $30 seems to be the cheapest, even if you already have a torch you still have to spend more than that on heat stop and SS.

However the fact that removal can be accomplished cleaner and easier with the SS sounds great.

Basically it comes down to the advantage of a clean removal vs. the possibility I am going to cosmetically damage my barrel and FH. No real way to permanently damage with the SS right?

Is my thinking correct or have I missed something?

Like a lot of what we do, SS will damage a barrel if done incorrectly.  Just follow the simple guidelines and you won't have any issues.
1.  HEAT STOP paste.  Use liberally.  I have seen some folks get real paranoid and glob Heat Stop on a bore patch and coat the inside of the barrel.  Not necessary but hey, if it makes you feel better....
2.  Good quality SS, preferably in paste form with flux mixed in.  Do not glob it on, apply to the threads only.
3.  Apply heat preferably from a MAPP or even better, an OXY/'MAPP.  The trick is to get it up to the appropriate temperature as fast as possible.  Put heat on the FH until you see the solder flow at the seam between the FH and the barrel.
4.  Remove heat immediately, put the barrel down to cool.

To remove, use HEAT STOP, heat the FH and turn it until it spins off.  Wire brush the threads.  Done.

On pin jobs, you usually have to destroy the FH by splitting it wih a dremel.  Done that a few times, easy to do but watch the depth of your cut or you'll be cutting your barrel as well.

I guess what I'm missing here is how much importance you're putting into removal of the FH.  The point is to make it a permanent part of the barrel so you don't run afoul of ATF regulations.  

The 1200 degree silver solder is the way to go, I have had both done, the blind pin by ADCO which was a piss poor job, I had to have some welding done over it locally to make it look good after I got it back.

My second one was the silver solder method and that is the only way I will do one from now on.

bchance1, one thing that you need to add to the price of the ADCO job is shipping both ways!  It seems a no brainer to me, the silver solder method is both easier and more cost effective, not to mention less down time for you.

JMO

I am having trouble getting the solder to work.

I am using jeweler's paste with flux already mixed in.  After applying it to the threads and screwing the FS on, the solder gets pushed to the back.  I heated it up, and I was able to fairly easily break the FS loose with a wrench.  The Solder ran, and the crush washer was the only thing perm attached.

Any recommendations on how to get the Solder to stay in the threads of the barrel?  Should I drill or cut out a couple of small holes in the threads to get he solder to stay?

Thanks for your help.

I am speaking here as a bench jeweler not an accomplished FH solderer....

Make sure that both the barrel and the FH (ESPECIALLY the threads), have been cleaned and degreased. Both items must be squeaky clean!!!! I like to use ether/starting fluid to clean parts. It cleans, and then evaporates completely. Dirty/greasy parts is the #1 reason solder will not flow between adjacent pieces.

The #2 reason solder refuses to flow, is when both pieces do not get up to a high enough temperature. Make sure you play the flame back and forth, and ALL around, over both the barrel and the FH. You will need to get BOTH pieces up to temp if you hope to have the solder join them together. Once they are both hot enough, IF they are both clean, capillary action will suck the solder throughout the joint.

Oh, and one last little hint: Solder ALWAYS flows TOWARDS heat. If you end up with too much solder in one spot and not enough in another, you can draw the solder through the joint by concentrating the heat where you want the solder to go.

Best of luck on your second try!  Hope this helps.....

/LOVES being a jeweler....
//HATES being a gunsmith....

That is not legal.  

I initially had the same problem.  We had to make sure the threads were VERY clean and after that, it worked.  Just as Emu said above, make those threads sqeaky clean, make sure you heat it well and it will work with good results.

i will be using the SS method in the next week. thanks to all the conversation before, i'm feeling pretty confident. i'll post/edit when i have it finished.

.....

I've heard that Silver Solder can corrode a barrel over time and that it isn't recommended... Anyone else hear anything like that?

I think I will just stick with the 20" barrels. All this Gosh Darn lawyer talk hurts my head. I had a vortex attached once(on a colt 14.5") and it looked like total crap.

Can anyone post a link the the appropriate MAPP torch?  I have a propane torch head laying around which I used to braze some copper pipe together last year, would that work if I got a MAPP cylinder?

Thanks!

This needs to be a "Sticky"!!!!

PursuitSS

This is what I use with good results:



Got mine at Lowes or Home Depot... can't remember which.

Here's the last one I did.  Phantom timed with a crush washer on a Colt 727 upper.  Brownells paste.  MAPP/OXY torch.  Brownells heat stop.  

Does anyone have any better pointers on this? I've been experimenting with the paste but am having a problem getting it to stick properly. Maybe everything isn't clean enough or something. I've been putting the paste on the threads and heating the brake on the area over the threads. I am using a heat sync paste, but on the one I did get to stick properly, it still discolored the barrel. Maybe I'm not getting the heat right. I'm using Mapp/Oxy. Any pointers?

First of all the inside of the Flash suppressor and the barrel threads MUST BE CLEAN! It wouldn't hurt to use a mild acid to clean them. Second, use a LOT of stop heat paste! Apply it inside the bore and above and below the area you are going to heat.

IMHO, the best way to heat the flash suppressor is to use a welding torch and heat it QUICK to a Blood Red outside the area where you applied the paste and then get off of it! If you take too long bringing it up to temperature, you will transfer heat to areas you don't want it! Make sure you have enough Silver Solder paste where you are going to heat it.

BTW, DO NOT quench the barrel after heating it. Let it cool down to room temperature on its own.

If I can pull this off, ANYONE can!

Black Red    1000
Blood Red  1200
Low Cherry Red  1375
Medium Cherry Red 1425
Full Cherry Red  1500
Bright Red  1550

PursuitSS

Will this work on a supressor. If it does anyone got any pics? I guess you would just heat up the base of the surpressor?

I am wondering the same. I have a SWR Wolverine can that I want to permanently fix to a 11.5" Bushy and silver solder looks like a great option if only I can get the base of the can hot enough and hot quickly enough. My back up plan is 4 equidistant TIG tack welds. All of this made necessary because Washington State does not allow SBR.

I would appreciate hearing from anyone who has attempted the silver solder method to affix a can.  Thanks in advance!!

Good thread!  

I'm gonna buy an 11.5" barrel and SS my Gemtech onto it.  Suhweet!  A 1-tax suppressed sbr!

The post a few slots above, listing various temperatures for various colors is good info.  

The MAPP approach is good because it's next to impossible to get steel hot enough with a MAPP cannister to alter it's metalurgical properties, provided you don't quench it in water to cool it.  Repeat - do not quench; just let it cool by itself.  

Faster heat transfer is optimal, but not critically essential.  Any changes you make to the steel of your barrel, FH, or quality suppressor while using MAPP gas will be purely cosmetic, not metalurgical.  A faster heat session with an oxy/acetylene welding torch simply enables you to focus the heat-ramp better on the work area.  Since a MAPP torch will take longer to get the work area up to heat, more of the barrel and can will get hot, and potentially discolor.  I'd think this would be more of an issue for stainless barrels than parked barrels.  

The heat paste or a wet rag is the solution to controlling heat migration.  

I guess it's possible that some cans have silver soldered caps.  If so, no big deal as long as you don't unscrew the can during the brief peak heat cycle, which would be counter to what you're doing anyway.  

Soldering is actually quite easy.  

Clean both surfaces using brushes and solvent.  Rinse well with a spray can of starter fluid or carb cleaner.  If you use starter fluid, be sure it's the variety that does NOT contain a lubricant.  Some starter fluid brands include a cylinder lube in their formulation.  This would give you fits.  You want pure ether.  Walmart brand $1.39 carb cleaner is a great non-residue degreaser.  

A true solder paste that contains both flux and solder is ideal.  Easy to find.  See earlier posts.  Stir it well to get a nice working consistency, and put a nice light coat on both threads.  Assemble.  You want to have a slight ring of it pushed up around your crush washer or can once threaded on completely.  If it's a huge glob-ring, you used too much.  I'd disassemble it, wipe it clean, and do it again with less paste this time.  

The slight ring of paste will be your tell-tale.

Cut 2 strips of "t-shirt" material 3" wide by 6" or 9" long or so.  Get them generously damp, but not dripping.  Wrap the barrel and can leaving only a half inch or so of the barrel and of the can exposed.  A wrap of three layers will be sufficent.  Use tape on the far end of each to hold them in place and keep them from unraveling.  Find an eye-dropper or pediatric tylenol medicine dropper and some water.  

Clamp the gun so that you can circle the flame uniformly on all sides of the joint.  Heat the joint aggressively and uniformly.  Use the eye dropper to re-wet the wrap as necessary.  Yes, you will char the edges of the wrap, but keep it damp as you go.  

The solder component of the tell-tale will melt right away when you start to heat.  

But you're still a long way from melting the solder.  Just stay on it, heat uniformly, with a slight extra-heat bias for the part of the work area that is easiest to see.  Watch the solder.  At some point, the solder in the bias area will suddenly melt and wick in to the threads, nearly vanishing.  Immediately continue a slow cylce around the joint until you've chased that effect all the way around the barrel.  This last step should take less than 5 seconds.  Turn off torch, check to see that your workbench is not on fire, place a final drop or two of water on each wrap edge, and have a beer.  When the work area is cool enough to touch, test your job by attempting to uncrew the FH or can.  It will either feel like a rock-solid single piece, or it won't.  On a parked steel, CLP will mask most of the evidence of heat on the work area.    

The chalk on the work area is a good idea for catching melting solder so it doesn't leave a residue.  

While heating, use water drops from the eyedropper only on the cloth wrap, not the work area.  

If the solder beads up and does not flow into the joint when it melts, agrressively apply heat right to the joint at that location for 8 seconds.  If it doesn't flow in, you weren't clean enough.  Stop.  Let it cool.  Start over.  Remember - cleanliness is next to Godliness.    You want no dirt, no oil, no grease, no powder residue, no nothing.  Just clean bright dry steel.  Degrease the barrel and can near the work area so that hot oils don't migrate with heat into your work area.

Oh yeah - I'll post my own results once I've actually done it.  

BTW - I'm pretty sure that silencers are only legal in WA state if you DO NOT attach them to a firearm.  Better check into that.

You can save a lot of money by using HyloCool instead of the Brownells heat paste. I can't find it on their website, but my local Harbor Freight sells good sized bottles of it for like $5. We use it at my work but we get it directly from Hylomar. It's really amazing stuff, you wouldn't believe how well it absorbs heat.

Will this be sufficient for one FH?

http://www.amazon.com/gp/product/B000VQ9HX4

Also you just clean everything, apply this paste to the threads on the barrel and FH, screw the FH on, then heat it and you're good to go?  I know there's more little things to do from reading this thread like applying heat paste, etc.  But this is the general procedure correct?

OK just asking a question here, other than taking longer to heat up the solder, are there any other issues to using a propane torch? I am asking on the grounds that I already have a propane torch and I would prefer to use it if it isn't going to be extremely problematic. And if the only issue is that it will take longer, I can deal with that.

Should you only put the paste on the threads closes to the receiver and not all the way to the end?  It seems like if you did, it would get displaced past the threads and possible close or drip into the barrel.

How much and where do you guys apply?

Still waiting on my barrel, so can't post personal experience yet.  

Based on my experience soldering other stuff:

The paste is at least 50% flux.  Probably more.  So whatever volume of paste you apply, figure that only about 40% or so of that volume will remain after heat.    The goal is not 100% solder coverage within the threads.  Within the threads, gaps are going to occur, and they are okay.  If there are 12 turns, and you get a good bond in 50% of 6 of the turns, a breaker bar will break the barrel before that weld will let go.  

When the solder melts, it will wick into very tiny places, and it will always lay as flat as it can on clean surfaces.  A super-thin layer that wicks into threads will lock the threads permanently.

When you start heating, the flux will melt right away.  When you arrive at the necessary heat, the solder will melt.  When it melts, it happens fast, and it sort of disappears into the joint.  You'll see it happen, and you will know.  Keep the heat on the joint for 3 seconds to push heat into the threads, and then make a slow circle around the barrel for another 5 seconds.  That's it.  

The reason for uniform heating of the joint (from the start of the job) is that once the solder melts in the hottest place, a slow circle of the torch around the barrel will chase the necessary heat level all the way around and ensure a good bond.  When you pull the flame away, the heat loss is so fast that the joint will lock in less than 10 seconds.    

You want enough paste "piled" up at the proximal edge of the joint so that a tiny solder weld is visible when you're done.  Then an "inspector" can tell by looking that it's soldered on.  

Plumbers use a propane torch to solder copper pipe.  Works great.  But the materials are thin-walled, highly conductive to heat, soft surface (easy to clean and prep), and nobody cares what they look like when the job is over, so heat migration doesn't matter.  Yes - propane will eventually get you there.  But you can buy a MAPP gas cannister for $10 and use the torch head from your propane bottle, and get there much quicker, which will mean less hassle fighting heat transfer during the job.  

Your torch head needs to be the kind that makes a 6" long clean jet of blue flame; NOT the kind that makes a blue flame flower at the tip.  The flower flame will never get you there.  You can use torch heads interchangeably on propane or MAPP bottles.  The hottest part of the flame is the tip, so bathe the work area with the tip of the flame, not the base of the flame.  

Good question about a solder gob at the tip.  The only way to get this would be way too much paste on the accessory.  If you have too much, the muzzle will "bull-doze" paste in front of it as you thread the accessory on.  To avoid this, use a light coat on the proximal half of the threads of the accessory.  After paste-&-attach, but before heat, push a brush into both ends and "clean" the muzzle tip area a bit.  If you have a gob, the brush will either drag it out, or smear it flat.  Either way, it will be inconsequential.  Melting solder wants to wick into a clean small crack or fall into a puddle in a low spot.  IF you have excess material at the muzzle, and IF it melts (unlikely), and IF the gun is pointed slightly down, the material will fall to a low spot in the accessory, and later fall off.  It won't run uphill into a huge open space like a barrel.  But most likely, it won't even melt, because your heat threshold won't penetrate beyond the contact area of the threads.  

Use a light coat on almost the entire thread section of the muzzle.  The leftovers will get piled up at the washer as you thread the thing on.  You can wipe some off if it looks like too much.  If you don't get any material "piled" up at the washer, take off the accessory and add a slight amount of paste, then re-attach.  You want about an 1/16" bead of paste piled up all the way around at the proximal end of the joint.

After cooling, test your job.  If a wrench breaks it lose, go cleaner, use more paste, and try again.  

But this is unlikely.  Soldering is magically easy, and very effective.  The hardest part of this job is controlling heat migration so you don't ugly up your gun.  

I bought some HyloCool HERE.

I was planning on using rags and water, but what the heck.

Should the barrel be level, muzzle up, muzzle down?

And you put the solder/flux paste on the threads, screw the flash hider on then do the heating so it melts inside the flash hider right?

Sorry for the dumb questions, just haven't done any soldering before.

O.K. so the B.A.T.F. approves the Silver Solder method. Great.  Does anyone know if for any reason those of us in Corrupticut, sorry I mean Connecticut, an AWB state, that this might be an illegal method? Or do they just follow the same specs as the Feds?  

Just curious.  Lot's of great info here. As a DIY builder, I would love a way of not taking my guns to my local Smith (JoJo's I love you guy's sorry for this blasphemy) and be able to put on and off comps (no evil FH's for us) for our silly AWB on our regular length barrels.  Once you commit to a FF tube system you are committed until that weld is ground off....
This would seem to be a MUCH better idea for a home builder to Silver Solder than blind pin weld.  I too do not have a welder or drill press.

I've seen all the links for online, plus Brownell's, is this stuff available at a good Hardware store, like a really well stocked Ace Or True Value (represent Goody's East Haven, Family Owned!) or just the online places.  I've also got access to a Harbor freight.  

Or a mega Home can't find a worker for half an hour Depot?

I'd need the cooling paste, solder, flux, and torch.  I'd appreciate opinions on best options as I'm starting from scratch, and yes I've read all the posts, but there is a multiple array of options, and I am totally new to this area of home-building and don't want Big Brother taking me away.....

Thanks in advance guys.

Make sure you purchase the Silver Solder PASTE!. I would not try it using conventional silver solder (wire). The only place I've seen the paste is online.

PursuitSS

Do you have any Doit best hardwares around ?
http://doitbest.com/Solders+and+fluxes-Oatey+S+C+S-model-326098-doitbest-sku-326098.dib

Nope.  I've never heard of them.  But True Value has some hard to find stuff....I can always try.
We are due for a foot and a half of snow, this won't be an instant gratification drive to the hardware fix, after looking at the package, I bet my local hardware store has it.
They pride themselves on having hard to find stuff, and having three people ask you if you need help within 30 seconds of walking in the front door.

Why don't you use the low temp High Force 44 from Brownells.  It needs only 475 deg F.  No damage on the barrel.

Because the BATF say it it must be at least 1100 degree.  I just did 3 of mine with some 1145 deg. silver solder past with flux in a syringe applicator that I got off ebay, that and the Brownells heat stop, and it worked like a charm.

Out of curiosity, why not the wire?  I can't find any paste in my AO and need to put on a fh by Friday.  Don't ask, I'm good at procrastinating...

I wonder if you SS the set screw into the hole prior to grinding it off?

if the screw is ground down flush would it not look exactly like the welded pin that has been ground flush?  how would you prove/disprove either?

I'm deciding on what method would be best on a bead blasted stainless barrel and flash hider

If you get proper penetration of the weld you should not see the pin after it has been ground off. BATF would nail you on this!

PursuitSS

everytime I see an example of the proper weld you can see the pin

Ask a CERTIFIED welder if it is "welded" when you can clearly see the outline of the pin.

I posted this link on the first page and here it is again.  This is the stuff I used and it is enough to do several guns.

http://www.silversupplies.com/catalog/metals/silver_solder/paste.shtml

And is that legal hi-temp silver solder or just some low temp solder?

I would NOT use any silver solder that was not CLEARLY labeled 1100 degrees or higher.

PursuitSS

Well I dont know any CERTIFIED welders and ASAIK the ATF does not require any certification paperwork for the welding.

But here is a pic from one of the most popular places on this site to have the work done.  I can see the pin

I'm not certified but for all I know that could be a set screw, JB welded, press fit, anything.

My point was how would they prove/disprove the welding if you cant tell by visual inspection.

I'd like to drill through the FH into the threads put a long set screw in one that extends out about 1", 1100deg. silver solder that in place by heating the screw not the barrel directly,  then grind it flush.

this method would eliminate heating the actual barrel and discoloring a nice Noveske bead blast finish.

this would pass any wrench test, be easier to remove then the welded pin but harder then the 1100deg solder only. And easier to install then both

I know its not legit but I wish they would consider other options.

When I high temerature silver soldered mine it did not discolor the finish. To me the idea of a single pin holding it seems to be a recipe for failure. There is no way in hell that you can twist off one that has been properly silver soldered on.

PursuitSS

Thanks to this post, I finally got my 14.5 and Vortex mated together with the SS method.  It discolored slightly where the heatstop paste started to dry up beyond the applied area on the flashhider.  Slightly brown tinged, but nothing a little CLP couldn't blend up with existing finish.  The adjacent areas beyond the heatstop got to about 240 at the hottest with the temp gun after removing flame from area to be soldered.  Hope this wasn't too hot.