Request for Information on fitting barrel link

[beb1954]

i have a new 1911 barrel and i need to fit the link and pin to it. I have not ever done this before and didn't realize that there is a possible problem with lock up if it is not fitted properly.
I presume that the fit of the link between the 'towers' is only a matter of loose, not sloppy or too tight to kink or jam. I just presume this from looking ar all the others I have ever seen. Don't see that there is really any specs for that. However, I am getting from what I have been reading is that the distance from center to center on the holes in the link is the spec that is what is considered.
Is there someone who can tell me if I am on the right plane of thinking and them direction to carry it out? Any rule of thumb on link to use or not use? How does one determine this? I do not have the luxery of having different ones to test and test fired for performance. This is going to be a one time fit and fix...
thx..

[swifty]

The link should be loose enough to pivot freely, the link pin should be staked. Links can be too short or too long.

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If this is a new barrel, you need to fit the barrel to the bushing and slide prior to the link. Links are sold in several lengths to help achieve proper lock-up.

[ojisan]

After you are done with basic fitting of the barrel bushing / muzzle and the breech, assemble the gun and with the slide forward and in battery, see if the barrel hood can be pushed down with thumb pressure.
If the barrel moves down, you need a longer link...which link is unknown, there are three lengths, original being the shortest.
Enough movement to feel but not see is correct.
If you set the barrel too high, it can cause binding at the locking lugs and failure of the slide to go into battery.

[beb1954]

If the barrel moves down, you need a longer link...which link is unknown, there are three lengths, original being the shortest.
Enough movement to feel but not see is correct..

So could one start with a link of he longer length and then file or relieve it as needed for proper fit? This is not going to be some High End Target pistol, just something that will go bang when it needs to and hit relatively close to where it needs to.

I have searched on YouTube for something that is a bit more illustrated for my inexperience, but have found nothing... If I have the correct idea about this that is... thanks...

[JRJCP]

The barrel link. It's been called the Swinging Link..The Locking Link... the Falling Link...and...The Link. A lot of mystery surrounds that simple little machine...and several heated arguments have been mounted over its function.

What exactly does the link do?

The link has two jobs...Unlocking the barrel from the slide, and timing that event. That's it. It also acts as a sort of guide...to keep the barrel tracking in a fairly straight line as it rises and falls...but that's incidental.

The link isn't supposed to lock the barrel into the slide...though many pistols are out there that do just that. The vertical locking of the barrel is correctly accomplished by the bottom of the lower lug and the slidestop crosspin. If the barrel "Stands on the Link"...it's incorrectly fitted, and can eventually lead to problems. If it locks tightly on the link, the problems will show up sooner. The main issue being loosening of the press-fit pin that keeps the link in place. When the hole becomes elongated, it works to delay the timing of the unlocking and linkdown, which in turn can lead to damaged locking lugs on the barrel and in the slide. Some will even advise us to use a long link to "Tighten'er up"...but it's bad advice. Not only does it not help accuracy, it can actually hurt it, the degree of which depends on the hood fit to the slide.

When the barrel is standing on the link in vertical lock, the barrel is more free to rotate unless the hood is restricted by its fit to the slide. Barrel rotation is a function of the bullet taking the rifling as it passes through the bore, causing the barrel to "torque. When the barrel is locked by the lug bearing on the slidestop crosspin, it's supported on two sides, and thus more resistant to this effect.

The timing is accomplished via the center to center distance between the link's holes. One is anchored to the frame, and the other is anchored to the barrel. In recoil, the barrel and slide move rearward together for a short distance...about one tenth of an inch...and unlocking begins. By the time the slide has moved a quarter-inch, unlocking is complete, and the barrel is in the bed of the frame. That's a short distance for all that action to occur, and it happens fast. As little as .003 inch change in the centerlines of the two holes can make a big difference in the timing of that event. To put that in perspective, a sheet of 20 bond typing paper is about .004 inch thick.

A correctly fit link allows the lower lug's forward radius to bear lightly on the slidestop pin as it swings around that radius, and it allows the bottom of the lower lug to cam upward on the pin. Note that the lower lug is not parallel with the barrel axis, but rather is angled slightly. When the barrel is in vertical lock and in battery, the link shouldn't bear any of the load, and should not be in a bind at all. At that point, the barrel lug should be supported at the bottom and the rear by the slidestop pin.

Many production pistols allow the barrel to "Ride the Link" around the forward radius of the lower lug, and still fit correctly when the barrel is in vertical lockup. This is better, but still not right. The link is still bearing a load that it shouldn't, and the wallowing out of the pin hole is still a factor, though it won't occur as quickly as it will when locking on the link.

When the barrel rides the link around that radius, it affects the timing of the barrel rise, causing it to rise too early and too abruptly. The reason is simple. When the incoming cartridge hits the barrel throat, it pushes the barrel forward. When the barrel moves forward, it also moves UP. With the lug radius bearing on the slidestop pin, this rise is more gradual. When the barrel rides the link, the barrel rises quickly, and is higher in relation to the slide's position. This, in turn forces the cartridge to climb a steeper angle as it tries to break over to horizontal and enter the chamber. Many "Ramp and Throat" jobs have been done to correct a feeding problem when the link was at fault. Many have been over-throated and even ruined when the work failed to produce the desired results. (See "The Three-Point Jam")

When the barrel is in linkdown, the link doesn't lie parallel to the barrel axis. The link's position is roughly centered on the forward radius of the lug...Put the slidestop pin through its hole in the link and swing the link so that the centerline of the pin is aligned with the centerline of the radius. That's the link's position when the barrel is fully down.

Neither is the link dead vertical when the barrel is in battery. It sits slightly past center...about a half-degree or so in ordnance-spec pistols, and as much as one degree with match-fitted barrels. We can see that the link's movement is actually a very short arc. Given this, we can see that the barrel will rise to vertical lock without the link. It just won't unlock...or at least it won't unlock correctly. Most pistols will function without the link being there at all...but the locking lugs will be quickly damaged by firing the gun without the link. Hand-cycle the gun with the link missing, and the gun won't know the difference.

The link is said to "Pull" the barrel out of lockup...but I disagree. Once the link has swung through its short arc, it's static, and isn't pulling on anything. "Pulling" suggests that the link is actively moving the barrel downward. The link is stopping the barrel's movement, much like a tether, and forces the barrel to change directions through the momentum of its rearward movement. The link is simply an anchor that halts the barrel's motion and uses the barrel's speed and inertial mass to bring it down out of the slide. A technicality...but a point that can be used to fuel an interesting debate.

Linkless barrels don't use "Double Camming Surfaces" to unlock or lock the barrels. Their function is exactly the same as with the link, but without the disadvantages and complexities of a moving part. They are also harder to adjust for vertical lockup when they are out of spec...but they do prevent the misinformed tinkerer from installing a long link and causing other problems.