No. A good pin job leaves no visual indicator either.
A good silver solder job on a barrel is hard to do. It takes a LOT of heat since you have a big heat sink of a barrel draining heat. They can be done such that they look fine but it is hard hard hard.
I know Bushmaster has their issues but the 14.5" bbl on the Bushy I bought in 1996, had the Vortex pinned and sloldered so you could not see the mark with out knowing it was there. Once you looked at 6 o'clock it was clearly there but you would not have noticed it w/o looking for it. They did an awesome job with it. I miss being able to snap a bayonet on my AR! That may be the only reason I buy a 16" Middy. :D
Seeing as how we're working with 4150 milspec barrel steel and whatever alloy the muzzle device is manufactured from, how real is the "screwing up the heat treat" argument? Do these alloys have a heat treat floor of only a couple hundred degrees higher than the silver solder or is it much higher (several hundred degrees, 1,000 degrees perhaps)? Does the silver soldering process affect the chromelining of the bore underneath the heated area?
If there's plenty of margin to begin with between the barrel steel's heat treat floor and the silver solder melting point, and if there's no affect on the CL, then this argument is moot.
There are two types of silver solder, low temp (around 600 deg) and hi-temp (around 1200 deg).
Since the Batfe requirement for silver solder is that it must exceed 1100 degrees, you are supposed to use the 1200 degree stuff.
The heat treat damage floor for chromoly steels is around 1100 degrees.
100 degrees above that and you are surely beginning to anneal the barrel steel.
At 1600 degrees, the steel will be fully annealed.
Add to the fact that most people won't know the difference between 1200 and 1400 when heating up a piece of steel and you have an even larger likelyhood of fully annealing the muzzle of the barrel while silver soldering a muzzle device on it.
Now, will the barrel be damaged to the point of negative results from being annealed?
That's a whole different topic of discussion...
I called Brownells earlier today before posting this question and the tech person told me to pack the bore with grease to prevent damaging the bore. He said it would be very messy.
I've tried to permanently attach a flash hider with silver soldered and a MAPP torch and it was a major PITA. I've played around with silver solder and thought how hard can this be? The hardest part is estimating the temperature. The color of steel at 1100 degrees fahrenheit depending on who's chart your looking can be described as a dull cherry, dull red cherry, blood cherry, blood red, or dark cherry. WTF? It's not a color that's in a box of crayons. At 1200-1300 degrees, it's a medium cherry. 1400 degrees is cherry or full cherry.
Not hot enough and the solder won't melt, too hot and it flows out of the threads. That's not even touching on the importance of surface prep.
Been there, tried that. Not worth the trouble.
Yeah, I just sent my back to ADCO to have them pin and weld it. Should arrive this morning.
Mr. Rausch has conducted a professional AR technical discussion without kicking much in the way of baseless opinion about people and editorializing, concentrating instead on describing the process and providing examples. Let's be generous and say you've benefitted the discussion by providing a stark contrast to Mr Rausch.
Randall, thanks; you've answered some stuff I've been forgetting to ask for some time now.
I've pinned and welded only a few flash suppressors but would never do the silver solder due to the ATF heat requirement. But I have to say after seeing that picture posted by develdoglib. That person didn't know what they were doing. I've done a few silver solder jobs putting sights on shotguns that were parkerized. You parker first, carefully file, grind away parkerizing on the area to be soldered, tin your piece first, apply chalk to areas that you don't want solder to stick to, and use a low temp silver solder. Cosmetics are intact and the sights wont fall of. I'm not a professional, but get to play one in my garage LOL.
I guess I'm a wannabe for building an M4gery using the BCM 14.5" upper with pinned FH. I guess the fact that I wanted to closely replicate the weight and handling characteristic of an M4 does make me a wanna be.
I am also currently the Team Chief/Leader of a 6-man element that is part of an Airborne Army Reserve unit which may be deploying in the next couple of years to some mountainous country.
Oh yeah. I'm a wannabe. :rolleyes: