Welding oversized gas port?

[MQ105]

I’m really liking the idea of the gas block insert. It seems like a bomb proof product and simple to install. Even though they are willing to replace the barrel, they have always done right by me in the past and I think that may be a little overkill for something that is just .004” too large.



10.3” for m193 and 70/30 suppressor use.

Have you test fired as-is? If not, that would be step 1 for me. If you confirm the port is too large, make/buy a GB insert.

[sidewaysil80]

Have you test fired as-is? If not, that would be step 1 for me. If you confirm the port is too large, make/buy a GB insert.

I don't need to test fire, I measured with pin gauges. I wanted a .070" port and I received a .073+" port, might seem arbitrary but I was assured they would get the exact size I requested. I want to mimic the MK18 port size since from a reliability and longevity standpoint since that was the most tested/proven of all port sizes on a 10.3" barrel.

I'm just going to order the BRT Insert. They did a wonderful job on the cut and crown and I don't want to bust chops over something that is easily remedied with the insert, especially considering they heavily discounted the service due to the delay in time and port mess up.

[MQ105]

I don't need to test fire, I measured with pin gauges. I wanted a .070" port and I received a .073+" port, might seem arbitrary but I was assured they would get the exact size I requested. I want to mimic the MK18 port size since from a reliability and longevity standpoint since that was the most tested/proven of all port sizes on a 10.3" barrel.

I'm just going to order the BRT Insert. They did a wonderful job on the cut and crown and I don't want to bust chops over something that is easily remedied with the insert, especially considering they heavily discounted the service due to the delay in time and port mess up.

Your port may be too big (likely), but each barrel is unique. Yours may run well with .073, or it may need a port smaller than .070. Also, the insert size doesn't exactly mimic the same barrel port size. I advise you to start with an insert with a smaller port than .070. You can enlarge if needed.
Of course, you can do whatever you'd like. As someone who has done many barrel port inserts over the years, I have seen a decent variation in port size among barrels with the same length, gas system, and journal size.
Let us know how yours turns out.

[sidewaysil80]

Your port may be too big (likely), but each barrel is unique. Yours may run well with .073, or it may need a port smaller than .070. Also, the insert size doesn't exactly mimic the same barrel port size. I advise you to start with an insert with a smaller port than .070. You can enlarge if needed.
Of course, you can do whatever you'd like. As someone who has done many barrel port inserts over the years, I have seen a decent variation in port size among barrels with the same length, gas system, and journal size.
Let us know how yours turns out.

No I appreciate the insight, can you explain what you meant regarding the insert not mimicking the barrel port size? Before I read your response I ordered a .070" insert kit but I don't mind adding a smaller one to test first.

[MQ105]

Because the port is farther "downstream" in the gas flow, the size acts slightly different than a barrel port without an insert. They are close, though. Your set up may need .065 (or something) for proper function. It's easy to enlarge the port insert; you can't make it smaller...

[Bob Sacamano]

Get a BRT port. Would try the .067". Funny reading the comments, I thought I was the only one that got a gas port opened up against my desires following a cut down. Wonder if we all used the same shop.

.073 is not to the point where I would be super concerned about reduced barrel life. Next go around, I cant think of a reason to get anythong other than an AndroCorp 10.3" with .070" gas port.

http://androcorpind.com/556-nato-10-3-port-size-0-070/

[Clint]

The ports do seem to flow about 5% more than a barrel port, which normally isn't enough to worry about.

Using only Mil pressure ammo, the smaller .067" is worth a try.

[mig1nc]

I installed a .067 brt insert on a 10.5" Faxon barrel.

Worked great.

So easy even a caveman can do it... Or at least an idiot like me.

Edited for clarity.

Sent from my Pixel 2 using Tapatalk

[Iraqgunz]

.073 isn't the end of the world. Of course, we have people that still think the earth is flat, so there is that.

[Tigwelder1971]

If plugging the port, drilling and tapping for a set screw and then TiG welding would be the route that I'd go.