ProtoType

Didn't want to hi-jack a thread.
In your reply to C.J. you discuss the cause/effect of improper sized links. What would you find to be the best method of determining what size link to use, say in a malfunctioning pistol or in installing a new barrel?

ProtoType

George M.

Kuhnhausen's book. George M.

JohnnyT

ProtoType, that's a simple question that requires a complex answer. It'll take time and it'll have to be broken down into two or three separate parts. Since it's almost time for me to get busy with the dogs, I'll come back to it...but the first thing that must be understood is that the link shouldn't force the barrel into the slide...a condition known as "standing" or as some people refer to it..."locking" on the link.

More later.

ProtoType

JohnnyT, much appreciated. I'll check back.
George M, I have both of Kuhnhausen's books on the 1911 but most of the time a practical explanation by a good pistolsmith is more detailed and easier to follow.
Thanks to both,
ProtoType

JohnnyT

Part 2

The barrel's vertical support should come from both lower lug feet bearing on the slidestop crosspin. When the link is swung to the in-battery position, the hole should line up with the radius at the tips of the lower lug feet. If any of the link's area between the holes is showing...supporting the barrel by the link...you either have a long link or a short lug.

Ideally, the lug feet and the top of the link hole should be dead flush, supporting the barrel feet across its width, but sometimes that's a little difficult to arrange without elongating the hole at the top radius...which won't affect linkdown timing.

It's also not good for the barrel to "ride" the link excessively as it swings the lug knee over the slidestop pin. A little lift is okay, but I don't like to see more than about .003 inch off the knee, with the lower lug coming to bear on the pin as soon as it clears. Again, sometimes that requires elongating the hole at the top.

Now for the complicated part.

The link's on-center length is determined by the aggregate vertical dimensions of the gun, and which particular length is required to drop the barrel at the right time and with the correct clearance between the top of the barrel the the underside of the first slide lug.

If the pistol in question is found to require a .288 link, then that barrel is not long-linked with a .288 link.

If...on the other hand...the pistol requires a .278 link, and a .288 link is used...it is long-linked.

ProtoType

Thanks JohnnyT, I think I'm following. Gonna spend some time back in the books to get the picture of this firmly planted!

ProtoType

pistolwrench

I evaluate link size a bit differently.
There is only one proper sized link for any specific 1911.
The proper sized link will allow contact of the lower barrel lugs to the VIS
while providing minimal clearance between the bottom of the barrel and
the frame bed.
In every GI spec 1911 I have examined, the barrel 'stands' on the link.

JohnnyT

Agreed. In another thread, I made note of the fact that the rear of the barrel lug should hit the VIS before making contact with the frame bed.
Even contacting at the same time can lead to problems as the bed starts to accumulate carbon. It doesn't have to be a lot of clearance, but it does have to be there, or you risk pulling the lug off the barrel.

That hasn't been my experience. If the barrel stands on the link, it's either been long-linked or the lower barrel lug is out of spec. Most ride the link around the forward radius of the lug...but not in-battery.

George M.

The barrel link
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

JohnnyT

With no credit given, I notice.

pistolwrench

Hmmmmmmm........I believe I have read that somewhere before?
I'm guessing Jack Fuselier? His website appears to be down but I did
find this:
M1911

JohnnyT

Nope. After all these years, I still recognize my own write-up.

pistolwrench

I think I read that 'tome' at the Mad Greek's Place a few years ago.

JT, are you getting cantankerous in your older years?

JohnnyT

I am.

ProtoType

Wow! And I thought it was a simple question (there is no such thing when it comes to 1911's).
I looked through both of Kuhnhausen's books, and with all of the information here, I think I'm following. You can bet all of this is getting cut-and-pasted to my notes for future reference.
On a side note, this forum is really great for help and info.

ProtoType

JohnnyT

There's been a lot of misinformation over the years concerning that simple link...mostly because it's believed to be a device to "lock" the barrel into the slide...and once a myth is established and becomes widespread, it's hard to shake it loose. It's been called the "Locking Link" and a "Toggle" and recently, I heard somebody insist that it's a lever that not only locks the barrel but also pushes it down.

The plain truth is that the Colt-Browning tilting barrel doesn't lock vertically. It engages vertically, but it locks horizontally under opposing shear forces when the gun fires.

The link's single function is disengaging the upper barrel lugs from the slide lugs, and that event is timed. Switching links with different on-center lengths alters that timing of the barrel link down. Alter it a little too much, and you can create some very expensive problems.

George M.

No credit given as I don't recall where I got it, sorry. George M.

JohnnyT

No harm/no foul, George. That thing's been around for years.