Barrel Clearance

[JeffC]

I would love to learn all I can about barrel clearance. On paper, I read that you should have .020 clearance when the barrel is unlocked, I only have one that has that much clearance and Colt made it in 1918. My newer guns and especially my 2 Springfields have very minimal clearance. I'd like to know what is the proper way to add clearance and how does the barrel park on the frame, does it sit on the 'saddle' or does it sit on the 'ledges' (right above the slide stop pin holes). How much clearance should there be between the bottoms of the barrel feet and the cutout of the frame?

 

[JeffC]

See, I'm already learning

I pulled 3 of my guns down and when the barrel is hanging from the slide I have over .015 gap and when those guns are assembled one has a healthy gap(over .010) another has a comfortable .010 and the third has a tight .010 (Springfield).

I don't have proper guages, I apologize, so I improvised and made a couple from paper clips.

 

[1911Tuner]

The Gap

Howdy pard!

There are some who want a minimum of .010 between the top of the
barrel and the underside of the slide at .250 inch of rearward slide
movement. Others say a minimum of .012-.015 inch. I like things
a bit looser at .018-.020 but I can be happy with .015 inch.

If the gap is say, .010 and the barrel is riding the link after it gets off
the crosspin, going to a .003 shorter link can widen the gap a bit, and
cause the barrel to linkdown a little earlier. Try that route first.

If you need a little more, radius filing the bottom of the barrel at the chamber works...but just a little...maybe .003 inch max. That just a
bit more from the saddle, or bed...again .003 maximum. Better to get
a little from several places than all from one. If you take any from the
bed, the lug feet may not let the barrel go lower if they're fit properly
in the frame. LIGHTLY remove a little from the sides and just a whisker from the bottoms. In extreme circumstances, another .003 can be radius filed
from the locking lugs themselves, but this is a last resort. Learn to
correctly follow a radius with a file before trying it, and practice doing it
on scrap round stock before going at the gun. Easy to do, but hard to describe here. Any machinist can demonstrate it, but it takes a little
practice.

A correctly fitted barrel does not lay in the saddle, but is held off of it
about .001 inch by the fit of the lower lug/lug feet...Not many pistols
are set up like that any more, so you won't likely have to remove any
metal from that area if you take any from the saddle.

Cardinal Rule: If it ain't broke, don't fix it! If the locking lugs on the barrel
and in the slide don't show signs of rolling or peening on the front corners, the linkdown timing is probably okay.

Luck to ya, buddy!

Tuner

 

[JeffC]

For peace of mind I'd like to have as much clearance (as close to .020) as I can but I wonder if manufacturers actually look at that? On the other end is it possible for a barrel and slide to exist happily with almost no clearance assuming the timing is perfect in a 1911?

And how about the sides of the upper barrel lugs.... I have one pistol that showed signs of peening the sides of one upper lug. I dressed it down and evened the lugs out and watch for signs every range trip but see no further problems(1000 rounds since) to date.

 

[1911Tuner]

Clearance

Jeff said:

For peace of mind I'd like to have as much clearance (as close to .020) as I can but I wonder if manufacturers actually look at that? On the other end is it possible for a barrel and slide to exist happily with almost no clearance assuming the timing is perfect in a 1911?
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I'd say that they likely don't. which is why we see damaged lugs once in a while. If yours isn't showing any damage, and the pistol functions, it's not
really important whether they have .015 or .020 clearance. Either will do.
I like things a little on the high side for dirt to have a place to go. As for
zero clearance...probably not. If you see one that appears to have no clearance, try pushing down on the hood lightly and you'll probably see a little. Sometimes when a barrel is riding the link, it will do that. It's not
good to have to push on it, but it doesn't seem to hurt anything.
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And how about the sides of the upper barrel lugs
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Yep...The sides can be a little out-of-spec too, especially if the tops are
getting battered. The two don't necessarily go hand-in-hand though.
First...Be SURE that the sides are being hit. It may be just the way it
looks due to the extension at the front of the forward lug. If it's getting
bumped, a little light filing will usually relieve it. Take a little from the lugs and a little from the slide. A scrape works better on the slide than a file.
One of the signs of a problem in that area is short recoil due to the barrel
bleeding momentum from the slide. If your pistol is cycling okay, you probably don't have anything to worry about as long as the lugs look good.

Another little thing that you can do is to lightly break the front corners of the lugs. Bevel them all the way around with a smooth mill file, or even a pocketknife, and keep the bevel small...maybe .005 inch wide. This will give the barrel a fraction of a second longer to get out of the way, and the bevel work with the slide to cam the barrel down as it passes over it.
Lightly breaking the rear of the lugs in the slide can aid this a little.

Note that the above is a "Field Expedient" method, and may not completely
cure the problem.

Check to see if the barrel is riding the link first. If the link is a little long, it
delays the barrel linkdown AND sometimes doesn't let it drop all the way
into the bed without pushing on it. A .003 shorter link just may do the trick.

Luck to ya buddy!

Tuner