Ruger 10/22 accuracy upgrade: Shortening factory chamber to improve accuracy

Spoiler alert- it shoots!

Inexpensive, reliable and easy to use, the Ruger 10/22 is a common first rifle for many shooters. While there are many expensive aftermarket upgrades, including match grade barrels and drop in trigger groups, some shooters have made their stock rifles shoot exceedingly well.

The 10/22 has a fairly long SAMMI spec chamber, which allows it to reliably function with a wide variety of ammunition.  Some forward thinking gunsmiths determined that facing the rear of the barrel would shorten the chamber’s lead and increase accuracy.  Having extensively read about this modification, we obtained some factory take-off sporter barrels and shortened the chambers to see how it would affect performance.  Unlike a trigger job, which will help a shooter get rounds on target, this process directly addresses the mechanical accuracy of the rifle.

10:22 test gun

Prior to working on the barrels we shot a series of control groups with the same ammunition we would be using to evaluate our work.  The test rifle is a stock, synthetic Ruger 10/22 Sporter with a Nikon P-223 3×32 scope.  A five round group was fired at 50 yards for each type of ammunition using a front and rear rest.  Ammunition tested was Eley Edge, Eley Club, Wolf Match and Aguila cartridges.  The groups were measured center to center in inches by subtracting actual bullet diameter from the outside edges of the most distant shot in the group.  The results of the initial firing can be found in the results table below.  Note: some factory 10/22’s shoot exceptionally well, this one didn’t.

The contents of are produced for informational purposes only and should be performed by competent gunsmiths only. and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.

For use in this project, the following items were ordered from Brownells:

I don’t often work with rimfire rifles, so I was excited by the challenge.  I searched around the net and found a few references to shortening a 10/22 chamber, few had measurements, but some suggested .070-.080″.  Prior to cutting the barrel, I decided to measure the amount of freebore in the factory chamber.

measuring cartridge OALTo determine freebore, I measure the length of a cartridge and the thickness of the rim.  I’m using Wolf Match ammunition for this stage of the project.10:22 measuring bullet length I carefully remove a bullet and measure its overall length.

determining distance to lands on 10:22

The bullet is gently seated in the chamber.  A depth micrometer is used to determine the distance from the rear of the bullet to the chamber.

With these measurements, I can determine the amount of freebore in a factory rifle.  Subtracting the length of the loaded cartridge, less the length of the bullet and thickness of the rim, from the distance from the rear face of the barrel to the rear of the bullet seated on the lands, equals the amount of free bore in a factory rifle.  With the ammunition and barrel I was using, I measured .038″.  This is shorter than the .070-.080″ suggested in my research, so I decided to cut two barrels, one .038″ short and the other .075″ short to see how they would perform.

A word of caution on shortening chambers.  Ruger designed their chambers to safely fire a wide variety of ammunition, including the relatively hot CCI Stinger.  I would be hesitant to perform an operation like this if you intended on firing the relatively hot loads like the stinger. This modification should be considered safe in our test rifle only.

dialing in 10:22 barrel

To machine the barrel I held it in a set true three-jaw chuck. This kind of chuck can be dialed in a similar fashion to a four-jaw chuck.  I used a dial indicator to indicate the barrel off of the factory chamber.  Note the factory extractor cut on the barrel tenon near the end of the indicator in the photograph above.

facing chamber on 10:22

To cut the chamber shorter, I simply zero the lathe’s digital readout and take a series of light passes using a high-speed steel insert tool to remove material.  Keep in mind most of this cut is interrupted from the extractor groove (high-speed steel cutters work well on interrupted cuts).  I went approximately .010″ at time.  After the barrel’s shoulder was cut, the edges of the shortened chamber were polished with fine abrasive cloth.

facing cut on 10:22 barrel

The modified 10/22 barrel.  At this point the barrel can be cleaned and reinstalled.

Heading back to the same range with the same shooter and the same boxes of ammunition, we fired 5 round groups at 50 yards from a rest with a rear bag using the same barrel.  The barrel cut .038″ shorter didn’t show much improvement over the factory barrel, however, the .075″ shorter barrel showed remarkable improvement.  Groups were measured and recorded in the table below.

10:22 cut chamber group sizes

Initial group sizes are listed in the “before” column.  Final group sizes are recorded in the middle “after” column.  The “difference” in groups sizes is recorded in the right column.    While the best groups from the factory barrel at 50 yards  were around 1.5″, all four loads were now shooting around an inch at 50 yards!  Quite an improvement.

10:22 eley edge before and after

Eley Edge, before 1.565″, after 1.011″.

10:22 eley club before and after

Eley Club, before 2.968″, after .978″.

10:22 wolf before and after

Wolf Match, before 1.443″, after .993″.

10:22 aguila before and after

Aguila, before 1.549″, after 1.080″.

standard velocity cci

Here is a group of CCI Standard Velocity ammunition we fired for good measure.

Note:  Shooter, optic, rifle, barrel, range conditions and ammunition were controlled in this experiment.  The target size was different in the before and after groups (packed the wrong targets on the trip to the range).  Target size was not controlled, however, given our target shooting experience, we do not feel it skewed the results.

It appears the information we researched was correct in suggesting shortening the rear of the barrel .070-.080″.  The gun functioned well and accuracy improved.  This is a fairly simple modification that gives a lot of performance with a minimal amount of work, but there is a catch, and it’s a pretty big one.  Live rounds couldn’t be ejected without firing them because of the excessive jam into the lands.  Next barrel I try this on, I’m going to decrease the amount of material removed to see if I can maintain accuracy and still eject live cartridges that have been chambered.

Clark Custom Guns is known for this chamber shortening service on factory guns. I’ve read a number of reviews from happy customers, so if you are considering this type of work, you may want to contact them.  See the video below for more information (I am unsure how much they remove).

Moving forward, I plan on cutting a barrel .050″ to see how it performs and cycles.  Additionally, I’ll be performing more extensive modifications to factory Ruger 10/22’s to see how well they improve accuracy.

For parts to customize your 10/22, visit Brownells.

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