Fitting the 1911 Barrel, Part 4: Headspace

Fitting the 1911 Barrel, Part 4: Headspace

When factory 1911 barrels are produced, the chamber is cut measuring from the rear edge of the hood forward. As you remove material from the hood to fit the barrel to your slide, you are shortening headspace. If you drop a round into a barrel with short headspace, the rim will be above flush with the rear surface of the hood. This condition may prevent the barrel from locking. I have seen "drop in" barrels from major manufacturers with short headspace.

When the barrel is locked in firing position, the chamber end is higher than the muzzle and the cartridge base is actually making contact with the breech face at a slight angle.

My Clymer .45 ACP Go gauge measures .900 inches but we will need a bit more headspace for reliability so the round will not bind during chambering and also to allow a little room for crud.

Years ago I made my own Go and No/Go gauges for barrel fitting measuring .903 inches and .906 inches, respectively. The SAAMI No/Go spec is .920 inches, and I have only seen one pistol that would chamber a .920-inch gauge in decades of working on 1911s. The .45 ACP is a low pressure cartridge with generous allowable headspace dimensions, but if you are chambering a more intense round like .38 Super, the specs will be tighter.


Install the barrel in the slide with the Kart bench bushing, drop your Go gauge in the chamber and attempt to push the barrel up into locked position. The likelihood is the barrel will not fully lock. Remove the barrel and clamp it vertically in a vise.


The chamber will have to be reamed with a headspace reamer a little bit at a time until the barrel locks. Use cutting oil and go slow. You will note from the pictures I have installed a sleeve on my chambering reamer to control the depth of cut.

The depth of cut is controlled with feeler gauges between the sleeve and the barrel hood. Start with a .020î gauge, take a cut, check headspace.

If the chamber needs to be cut deeper, I go to the next smaller feeler gauge and take another cut. In this way, I closely control cutting depth. No mistakes, no overcut chambers.

Once your "Go" gauge will chamber normally, add a .003-inch feeler behind it. When the barrel will fully lock up with the "Go" gauge in place and a .003-inch feeler gauge, you're done. Try a .006-inch feeler as a No/Go check, but don't use the actual No/Go gauge. In fact, there really isn't any reason to buy a No/Go .45 ACP gauge.


At this point, we have fitted the hood, bottom lugs, link and cut the chamber. The last fitting step is the bushing. Stay tuned.

The Tools

Here are the tools needed for headspacing a .45 automatic: chambering reamer with sleeve, feeler gauges, Kart bench bushing and headspace gauge(s).

Short Headspace

Short headspace may cause the rim of the cartridge to protrude above the barrel hood, preventing the barrel from fully locking into the slide.

Go Gauge

Check headspace by attempting to press the barrel into full lockup with the Go gauge chambered. Most of the time, it won't quite go into position.

Lengthening the Chamber

Adjust headspace by carefully lengthening the chamber with a chambering reamer. This sleeved reamer uses feeler gauges to control depth of cut.

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

Gemtech Suppressors: Testing the Patrolman, the One and the Tracker

Gemtech Suppressors: Testing the Patrolman, the One and the Tracker

Patrick Sweeney tests and reviews a trio of Gemtech suppressors.

Transcoded: FANIssue11-SpringfieldEdgeEVAC

Transcoded: FANIssue11-SpringfieldEdgeEVAC

Patrick Sweeney of Firearms News shows off the Springfield Edge AR pistol with a folding arm brace.

Shooting the 20mm Lahti

Shooting the 20mm Lahti

David Fortier had the chance to fire the Lahti L-39 while filming the 2018 season of Guns&AmmoTV while on location at DriveTanks.com.

See More Popular Videos

Trending Articles

Rhode Islanders are setting brushfires for freedom once again as they advance a Second Amendment Sanctuary Town movement. 2nd Amendment

SPECIAL REPORT: BIG 2A HISTORY BEING MADE IN LITTLE RHODE ISLAND

John Peterson - May 22, 2019

Rhode Islanders are setting brushfires for freedom once again as they advance a Second...

The last of Germany's infamous Elefant tank destroyers. Historical

World War II German Elefant Tank Destroyers

Neal S Shera - July 12, 2019

The last of Germany's infamous Elefant tank destroyers.

If you want to keep the peace, keep and bear arms. Don't give up your guns. Any other choice would be ridiculous. 2nd Amendment

Is Red Dawn Really Just Ridiculous? If Not, Who Would Citizen Disarmament Help?

David Codrea - May 29, 2019

If you want to keep the peace, keep and bear arms. Don't give up your guns. Any other choice...

Governor Northam is calling a special session of the General Assembly on Tuesday, July 9th, to do nothing but pass more gun control! 2nd Amendment

Virginia Governor Northam Declares War on Gun Owners

Virginia Citizens Defense League - July 09, 2019

Governor Northam is calling a special session of the General Assembly on Tuesday, July 9th, to...

See More Trending Articles

More Gunsmithing

There was a time (a couple decades ago) when most 1911 front sights were staked in place as John Gunsmithing

How to Stake a Trijicon 1911 Front Sight

Gus Norcross - May 29, 2014

There was a time (a couple decades ago) when most 1911 front sights were staked in place as...

YouTuber, GunCraft101, builds an AR-10 from used brass casings. Gunsmithing

YouTuber Builds AR-10 Receiver from Used Brass Cartridge Cases

Jim Grant - July 06, 2018

YouTuber, GunCraft101, builds an AR-10 from used brass casings.

I rolled onto the range late in the afternoon with a couple rifles to test-fire. I had it all to Gunsmithing

Savage Trigger Upgrade From Sharpshooter Supply

Gus Norcross - April 02, 2014

I rolled onto the range late in the afternoon with a couple rifles to test-fire. I had it all...

In Part 2 we left off with our gas system installed, ready to screw on the fore-end tube. Most AR Gunsmithing

Building a Heavy AR-15 Varmint Upper Part 3: Final Assembly & Test Fire

Gus Norcross - January 27, 2014

In Part 2 we left off with our gas system installed, ready to screw on the fore-end tube. Most...

See More Gunsmithing

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Get Digital Access.

All Firearms News subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now