Before we start, let’s get this out of the way: Repeal the NFA!
Got that out of your system? Good. Let’s move on.
I was first introduced to the idea of a pinned & welded AR barrel in about 2011. NFA laws being what they are, a rifle has to have a barrel of 16″+ to not be considered a Short Barreled Rifle (aka, SBR). That rule is oppressive and arbitrary and dumb, but we can work around it.
The US Army uses 14.5″ barrels on their M4 carbines. They can do this, because they are working for the government. It’s the classic “You can’t do it, but I can because I said so”, but that’s irrelevant to this particular post. Why 14.5″? Why not 14 even? Why not 15? A quick google search indicates that 14.5″ (with carbine length gas tube) was the shortest length to which they could still attach their bayonets. I have no idea if that is really the case or not, but it’s also irrelevant to this discussion.
The problem occurs when civilians want to be like the military and use what the cool guys use. The US military issues SBRs as the standard service rifle. (I’m trying really hard to not make this into an anti-NFA rant) Us normal folk (aka, “normies”) can’t run 14.5″ barrels on our rifles unless we register them as SBRs. That means that we have to fill out registration forms, pay $200 to the government, wait for months, and then what do you have? A rifle that you cannot take accross state lines without express, written permission from the ATF. Totally worth it, right?
So, what’s a gun bro to do? A lot of people noticed that the military’s standard issue muzzle device, the A2 flash hider, is a little over 1.5″ long. If they permanently attached an A2 flash hider to their barrel, they’d be legal and they’d achieve the look they want. It looks like what the boys ‘over there’ use, and it doesn’t have ridiculous legal baggage that comes along with it. It’s a win-win. Well, only if you never want to modify the rifle at any point in the future. ‘Permanently attached’ muzzle devices can be removed, but you run a very real risk of severely damaging the barrel, and that’s when you’re paying a gunsmith to do it. To understand that aspect of it, we need to understand what ‘permanently attached’ means.
First, let’s go over how to ‘permanently’ attach a muzzle device. This is usually done by drilling a small hole in the muzzle device (if it doesn’t come with one already), driving a pin into the hole so that the device cannot come off the threads, and welding that pin in place. When you see someone mention a “pinned and welded” barrel, that is what has been done. To remove a pinned & welded muzzle device, it means locating the welded-in pin, drilling out, but not drilling into the barrel threads, and then removing the device. I’m not a fan of this method.
Another way of attaching a muzzle device is to use 1100°F degree silver solder to attach it, but that’s very uncommon. I’ve only heard one person mention it, and he was a gunsmith. I assume that to remove the device, you would re-heat the muzzle end of the barrel and unscrew the device once the solder melts. I like this way better. Based on the material properties of 4150 Chrome-moly steel and 416 stainless, 1100°F is far enough below the point where you start screwing up the hardening of your barrel, as long as you don’t go much above 1200°F. If you reach 1500°F, you’re playing with fire. Be very careful, and pay a professional to do it when appropriate. I don’t care how cool your M4gery looks with a 14.5″ barrel, you’ll look real stupid when your barrel explodes.
Now that that’s out of the way, why should you care about modifying your rifle? Can’t you just run what the Army runs and be fine? Well, what if you don’t want to run an A2 flash hider? Want to try out a muzzle brake for competition this year? Too bad. Between the different handguards different brakes, comps, & flash hiders, the recent rise of QD suppressor mounts, and even the SB Tactical Arm Brace, having a pinned & welded barrel is idiotic. Take free float rails for an example. If you (like me) didn’t get MLok on all your rifles, you’re probably wishing you did. If your flash hider is pinned & welded, you have to pay someone to get that handguard switched out, and if you don’t replace the barrel entire barrel and gas system, you’re either paying that guy to re-weld that flash hider back in place or filing SBR paperwork. Pinned & welded a QD suppressor mount to your barrel? That’s pretty smart, until your can is completely outclassed by the competition and you have to factor the costs of switching out a permanently attached mount for another permanently attached mount..
The muzzle device basically has to come off any time you want to change anything about your upper (besides swapping the entire barrel and gas system together). It’s like the very last thing you put on the gun, and permanently attaching it means that everything else behind it is just as permanently attached. One of the most appealing aspects of an AR is the ability to change it to your liking, permanently attaching your muzzle device completely nullifies that whole aspect. It’s like building Legos with glue.
*you, getting your 14.5 pinned & welded
There really is no reason to pin & weld devices on your AR in 2018. It was never really a good idea. A 14.5″ didn’t save enough length to justify NFA paperwork, tax, and wait times, and the length savings over a 16″ barrel wasn’t enough to justify the hassle of pinning & welding. That was back then, there is even less reason to do so today.