I have a brand new 6920 barrel that I sent off to have cut down and the port opened up to .070”. Unfortunately the gas port was overly enlarged due to an internal communication issue at the shop. I want to reuse the front sight post/gas block so simply installing an adjustable gas block is out of the question.
The shop is incredibly helpful and offered to either weld the port and redrill or replace with a new Colt barrel (in another email). I don’t want them to have to source a new barrel if the weld method is equally or even stronger than a factory gas port. But I’m unsure how durable it would be and if would erode quicker or be a weak point. Has anyone ever heard of this technique or is familiar with welds on a gas port? Here is there explanation below…
For “repair”, the hole can be laser welded and re-cut. The weld does NOT get into bore line so no worries of burrs. If for any reason we look at it and decide that isn’t a suitable fix, we’ll replace the barrel with a new one. We’ve closed holes with the welding/re-cut in the past for various reasons and it has always worked fine. The welding is via a microscopic laser and it leaves very little weld on the barrel surface. But that all gets cleaned up. Barrel shouldn’t need re-parking but if it does we use the same parkerizing solution Colt and other .gov MFGs use.
You’re talking nitrocarburized steel. Any metal they add to it will wear faster. Significantly faster. I just can’t imagine how they would get it really precise and pentrated weld without risking metal getting into the barrel itself or only lightly tiging it and, again, risk of lack of penetration and wear resistance.
I am no shop worker or metallurgist. So, Your Mileage Will Certainly Vary.
I’d be flustered and ask them to source a new one. Just my opine though.
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.
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.
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.
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…
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.
