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.

Recommended for You

The Soviet short sword of World War II was the Pistolet Pulyemet Shpagin-1941 (PPSh-41) submachine gun. Rifles

Shooting the Soviet 7.62x25mm PPSh-41 Submachine Gun

David M. Fortier - July 11, 2019

The Soviet short sword of World War II was the Pistolet Pulyemet Shpagin-1941 (PPSh-41)...

Want the “Holy Grail” of AR-15 rifles? Brownells has made that possible with their BRN-Proto retro rifle. Rifles

Brownells BRN-Proto Retro Rifle

Patrick Sweeney - July 02, 2019

Want the “Holy Grail” of AR-15 rifles? Brownells has made that possible with their BRN-Proto...

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 Recommendations

Popular Videos

Springfield Armory Saint Victor in .308

Springfield Armory Saint Victor in .308

The Saint Victor in .308 features a 16" light weight barrel, M-Lok® free float hand guard and included flip-up sights.

M134 Mini-Gun

M134 Mini-Gun

While filming the 2018 season of Guns&AmmoTV we had the unique opportunity to fire the M134 Minigun.

Kyle Lamb and Eric Poole talk SIG pistols

Kyle Lamb and Eric Poole talk SIG pistols

G&A Editor Eric Poole and Viking Tacticals's Kyle Lamb talks about 2 new pistols from SIG Sauer and a Lipsey's Special of the P365.

See more Popular Videos

Trending Stories

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...

This will be the first of many investigative reports about the NRA by Firearms News. 2nd Amendment

Firearms News Investigates the NRA: Part 1

Nedd Scott - July 18, 2019

This will be the first of many investigative reports about the NRA by Firearms News.

No one can restore receptivity to another Trump term with these disaffected gun owners but the president himself. 2nd Amendment

2020 is Trump's to Blow with Gun Owners

David Codrea - July 09, 2019

No one can restore receptivity to another Trump term with these disaffected gun owners but the...

See More Stories

More Gunsmithing

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.

AGI's new Certified Glocksmith Course includes Complete Disassembly & Reassembly, the GLOCK Gunsmithing

AGI Glocksmith Course

SGN Online Editors - April 09, 2014

AGI's new Certified Glocksmith Course includes Complete Disassembly & Reassembly, the...

I have long been a big fan of Savage 110 series bolt action rifles. They are an extremely good Gunsmithing

Rebarreling a Savage Model 11

Gus Norcross - February 04, 2014

I have long been a big fan of Savage 110 series bolt action rifles. They are an extremely good

See More Gunsmithing

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction.

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT ISSUE

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