Make An Accurate .22 Semi-Auto

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Ruger 10/22 with bull barrel works well in the field and shoots 1/2-inch 50-yard groups with CCI standard ammo.

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T
HE CONCEPT OF an autoloading .22 rifle which is both handy and highly accurate is very attractive. How often have you lost the opportunity for a second shot at a squirrel or other small game because the action noise and movement of your hand spooked the animal? Semi-autos mask the action noise with the report of the rifle.

If you can, as well, use subsonic ammunition — it doesn’t provide the supersonic “crack” which accompanies the “whiz-bang” stuff — game targets are often unaware of that first shot. The shooter who remains motionless after a near-miss often gets a follow-up shot.

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The tough part of shooting the semi-auto on squirrels is that many autoloaders simply aren’t accurate enough for clean kills, except at short range. Part of that is because light rifles are hard to hold steadily, but there is also an inherent limitation in the design compromises made to obtain safe and reliable functioning. The few semi-auto .22 rifles you see that are consistently accurate are greatly prized by their owners, most of whom know their rifles are aberrations.

Squirrels have tiny vital areas. The maximum effective range for a small game rifle is determined by the longest distance you can confidently fire a 1-inch, five-shot group from a field position. I have found that ten-shot benchrest groups under controlled conditions on the range approximate what I can expect for five-shot groups under field conditions shooting from an improvised rest. This realistically limits the average .22 autoloader to 30-40 yards.

If your rifle functions reliably with standard-velocity or match ammunition (an iffy thing with some autoloaders), you might reduce your benchrest ten-shot group sizes to 1/2 inches at 50 yards. A few autoloaders do better with a particular ammunition they like, if you can discover what that is and then hoard some. Most .22 bolt actions, when scoped, will easily beat an inch for ten-shot groups at 50 yards. A very few will approach half that with good match ammunition. The obvious way to make an accurate .22 autoloader is to do what Navy gunsmiths did for CISM competition.

The January, 1990, issue of American Rifleman shows a heavy target barrel from a Winchester 52 and custom McMillan target stock installed on a Ruger 10/22. The rig certainly looks interesting, but is hardly the type of thing I would want to carry up the ridges. It’s also a little strange to put $500 worth of gunsmithing into a $150 rifle!

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It’s almost all in the chamber, and Jim Coleman knows how to make the right one happen in a semi-auto.

Because there was no accuracy data, I could not determine from the Rifleman article how well the Navy-CISM rifle really shot.

Shortly afterward, several magazine articles described the Clark-Custom Ruger 10/22 autoloader built for the Chevy Truck Sportsman’s Team Challenge. It has a 21 1/2-inch heavy Douglas barrel and supposed match-type chamber, but retained the Ruger’s trim sporter stock. This makes a handsome 7-pound package which appears to have obvious field utility, but the developed accuracy reported in several write-ups I’ve seen was uninspiring. The March, 1991, issue of American Rifleman shows several series of five-shot, 50-yard groups with high-velocity ammunition averaging from 1.3-1.8 inches. That implies that ten-shot groups, which are the usual industry standard for .22 rimfire ammunition testing, would be in the “ordinary” 2-inch range. Shucks, a third of normal-production Ruger 10/22s will shoot 1/2-inch ten-shot groups from a rest with CCI Green Tag, straight from the box!

From 1984-86, I observed thousands of rounds fired through 10/22s every day at the Newport, New Hampshire, Ruger factory. Occasionally, range staff would conduct audit shoots of normal production. When I was with the company, it was not unusual to get a dozen rifles from a rack of thirty which would shoot 1/2-inch ten-shot groups at 50 yards with CCI Green Tag, and function reliably, too, with seldom a bobble.

The various test results I’ve seen on the Clark-Custom don’t seem like much of an accuracy improvement from my memories of factory testing the 10/22, considering that the custom gunsmithing added about $300 to the cost of the basic rifle! The NRA tech staff tried Eley Tenex ammunition in the Clark rifle, but it malfunctioned and no accuracy data were reported. We don’t know what the Clark-Custom would do with good ammo when tuned to function reliably with it.

If you watched the 1991 Chevy Truck Sportsman’s Team Challenge last year on ESPN, you probably noticed the shooters lost time clearing jams. I have watched this tape several times, and it made the lasting impression that the gun modification wasn’t completely worked out.

 

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Scoped — it’s a 6x Unertl — Norinco proved to be so good as-is it was left alone — the exception that proves the rule.

The Ruger 10/22 is, generally, one of the most reliable .22 autoloaders ever made. Feeding malfunctions will occur in some autoloaders with standard-velocity ammunition, because it doesn’t provide as sharp an impulse to work the mechanism. If the action spring is balanced for high-velocity rounds, the usual case with U.S.-made autoloaders, standard-velocity rounds don’t provide full compression of the action spring, and the shorter bolt stroke reduces the bolt closing force imparted by the action spring. This condition gets worse when the gun gets dirty.

The traditional .22 Long Rifle SAAMI-dimentioned “match” chamber isn’t suited for use in autoloaders. This is because additional force is required to seat a 22 Long Rifle round that last 1/10-inch or so into the origin of rifling in the match chamber. This increased resistance causes failures of the bolt to close fully, because semi-autos depend upon the inertia of the closing bolt to seat the round. It is necessary to adjust forcing cone depth to the particular ammunition when the tighter body diameter, match-type chamber is used.

It is no secret that the accuracy potential of a .22 rifle is determined by its chamber. The SAAMI-dimensioned .22 Long Rifle sporting chamber is seldom capable of much better than 1 1/2-inch groups at 50 yards, no matter how heavy the barrel is or what kind of ammunition you try. However, many .22 semi-auto target pistols group well under 2 inches at 50 yards with match ammunition when scoped or fired from a machine rest. If you cast the chamber of a .22 rimfire match pistol, you will find it doesn’t have the usual sporting chamber. It doesn’t have the same chamber that match rifles do either. It is something in between, which is exactly what we are looking for.

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All these were shot through a Winchester 52D-chambered heavy barrel of 16 1/2-inch length fitted to a Browning .22 semi-auto rifle. Targets 1 and 2 show a best group of .424-inch — ten shots at 50 yards — and a more typical group at .67-inch made with excellent Eley Tenex target ammo. Targets 3 and 4 show a best of .483-inch and a typical .826-inch group, this time with CCI Standard Velocity cartridges. Targets 5 and 6 were made with Eley Subsonic hollowpoints — a typical .911-inch group and a best at .778-inch. This was an accurate .22 semi-auto, indeed.

The Ruger Mark II Government Model pistol uses a shallower 2-degree lead angle in the forcing cone of the chamber, rather than the standard 5 degrees. This permits the chamber body length (measured from the rim seat to the start of the forcing cone) to be shortened to .670-.700-inch length, which is a compromise compared to the .600-inch of the SAAMI-dimensioned .22 LR match chamber or .775-inch in the SAAMI sporting chamber.

Research more articles about the Ruger 10/22 using Gun DIgest Research - Over 65 Years of Gun Digest books onlineWhile this chamber greatly reduces free bullet travel compared to the sporting chamber, engraving force on the round being chambered is far less than the SAAMI-dimensioned match chamber. A safe, reliable autoloader which functions with anything and isn’t fussy about cleaning requires about 1/16-inch longer body length than the SAAMI match or Winchester 52D chamber. I recommend the gunsmith making rifles for the average user adopt a chamber as shown in the accompanying drawing. It includes a .228-inch base diameter, .670-inch minimum body length with up to +.030-inch if needed for reliable function, .225-inch mouth diameter, and 2-degree forcing cone. In my humble opinion, the chamber illustrated is the best way to go for all but the most serious accuracy requirements. It will also work well in manually operated repeaters and semi-auto pistols.

Serious shooters after pure accuracy, who are willing to select specific ammunition and clean carefully, can use the Winchester 52D or Freeland-type chamber in autoloaders like the Browning or Ruger and can expect accuracy which rivals a boltgun. The Winchester 52D chamber has a .580-inch body length, whereas the similar Freeland type is .600-inch. Both have a 2-degree forcing cone which engraves a round of Eley Tenex to about the second cannelure upon chambering.

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The second-best and second-worst of ten-shot at 50 yards with a factory ATD demonstrate that some rifles should be left as-is.

This chamber generally works well as long as the guns are well tuned to function smoothly and are kept clean. The shorter Winchester 52D and Freeland-type chambers may sometimes experience malfunctions with foreign ammunition exceeding SAAMI maximum bullet diameter, or if the chamber is used in rifles with light breech bolts or weaker action springs. These rifles and manually operated slam-feeders with little chambering leverage, such as the old discontinued Winchester Models 1890, 1906, 61 and 62, require the chamber body be lengthened about 1/16-inch to obtain reliable functioning. Gunsmiths wanting to ensure reliable functioning in autoloaders, which will work with any ammunition and go 1000 rounds or more between cleanings, should try this lengthened chamber.

A viable expedient for gunsmiths not wanting to buy special tooling is to use a .22-caliber centerfire rifle throating reamer (usually .2245-to .2250-inch diameter with a 1- or 3-degree angle) to carefully lengthen the SAAMI-dimensioned match chamber approximately, but not appreciably more than, 1/16-inch. The exact body length is not critical as long as chamber diameter is maintained as close as possible to the SAAMI maximum cartridge diameter of .225-inch. A round of the chosen ammunition dropped by its own weight into the chamber should stop about 1/16-inch short of the rim seat. Lengthening the match chamber slightly reduces resistance to chambering while preserving a close fit of cartridge to chamber, which is essential to best accuracy.

Simply shortening the sporting chamber by stopping the reamer before it cuts to the full .775-inch depth from the rim seat does not work, because chamber diameter is more important than length. Running a 2-degree, .225-inch diameter rifle throater 1/16-inch into a SAAMI match chamber only enlarges the average of a series of ten-shot groups about 10 percent.

This is insignificant. Further deepening the chamber another 1/16-inch increases group size by 15-18 percent over the original match chamber, which is only marginally significant. But enlarging the body diameter of the same chamber only .005-inch by cleaning it up with a sporting reamer, just enough to get reliable semiautomatic functioning, doubles group size compared to the Winchester 52D-type chamber. You don’t need to be a statistician to see that doesn’t work.

We fired several factory .22 autoloaders to get a baseline for comparison. These included a Ruger 10/22, a Browning Grade I autoloader, a Norinco ATD copy of the Browning from Interarms, and a circa-1970 Remington Model 77 Apache. All of them shot remarkably alike. The Remington did not function reliably with all standard-velocity ammunition, but the Ruger 10/22, the Browning and the ATD did. The ATD shot fully as well as the Browning, a pleasant surprise. I had intended to reline the ATD as an experiment, and then shoot it again for comparison. But when I saw the targets with CCI Standard Velocity and Eley Subsonic Hollowpoints, my chosen squirrel ammunition, I took Jim Coleman’s advice that “if it ain’t broke, Mister, don’t fix it!”

Our results suggest that over the long run most .22 autoloaders will average 2 inches or so for five ten-shot groups with high-velocity ammunition. Standard-velocity ammunition was more accurate, averaging about 1 1/2 inches. The Browning approached 1-inch with Eley Tenex ammo, as did the Norinco ATD with Eley Subsonic HP.

If you are unwilling to test a parade of .22 autoloaders until you find an accurate one, the least expensive way to get a tackdriver is to install a Brownells liner in a factory barrel, with a proper chamber. I recommend use of the SAAMI-dimensioned match or Winchester 52D-style reamer, adjusting the forcing cone not more than .060-inch deeper with a .22 centerfire rifle throater until rounds chamber and extract easily, but are engraved for about 1/16-inch when extracted without firing. Arlington, VA, gunsmith Jim Coleman has found that relined barrels with good chambers average under an inch, with the best ammunition being 1/2-inch or so. However, because the light factory barrel contours are whippy, they are very difficult to hold steadily. Getting consistent grouping remains a problem, so a heavier replacement barrel is the preferred option if you want the “all-out-accurate” autoloader.

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Burst cases can happen to the regular SAAMI-spec match chamber in a 22 semi-auto.

At Coleman’s suggestion, we decided to see how well we could get an all-out-autoloader to shoot — heavy barrel, target scope, the works. George Wilson of the Wilson Arms Co. provided several blanks of the same type he supplied to Ruger for producing the 10/22. These are 1137 steel and 15/16-inch diameter, providing a finished barrel 20 inches long. Fitting these cylindrical blanks on a Ruger 10/22 and a Browning autoloader, we reached our goal — an autoloader which would average under an inch for a long series often-shot groups at 50 yards. We also proved to our satisfaction that the Winchester 52D chamber or something similar with a gradual forcing cone, optionally up to 1/16-inch longer (depending on the intended ammunition and your cleaning habits), was necessary.

Our early trials with the SAAMI-dimensioned match chamber in the Browning produced malfunctions. Once the gun was dirty, we blew off a few case heads from slamfires. One of these is illustrated. I would caution people never to use the SAAMI-dimensioned match chamber in an autoloader.

Actually, two heavy Wilson Arms Co. barrels were fitted to the Browning .22 autoloader, chambered to Winchester 52D dimensions. One barrel had the normal 16-inch twist and the other was 14-inch twist, as used by Clark in his custom target pistols, which we tried just to see if it made any difference. It didn’t. The average of fifty ten-shot groups in the Browning autoloader using an assortment of high-velocity, standard and match ammunitions at 50 yards was .99-inch with the 16-inch twist barrel and .95-inch with the 14-inch twist. Eley Tenex averaged under 1/2-inch in both barrels, CCI Green Tag, CCI Standard Velocity and Eley Subsonic HP averaged under an inch. None of the high-velocity ammo averaged over 1.2 inches.

Looking at the Clark-Custom Squirrel Rifle advertised recently in several shooting publications, we decided to shorten the barrel on the 14-inch twist Browning heavy barrel. The results were gratifying. Ten consecutive ten-shot groups with Eley Tenex averaged 0.67-inch, a significant improvement from the 0.74-inch average produced by the same barrel when shot at 20-inch length. Results obtained with CCI Standard Velocity and Eley Subsonic HP were essentially unchanged from the same barrel at 20 inches, being 0.71-and 0.89-inch, respectively.

The accuracy obtained with heavy 20-inch barrel and Winchester 52D chamber on the Ruger 10/22 was similar. Nineteen ten-shot groups with CCI Standard Velocity averaged 0.75-inch, with the largest just over an inch and the smallest under a half-inch. With Eley Practice 100, eleven ten-shot groups at 50 yards averaged 0.71-inch, with nothing over an inch. Federal Lightning high velocity averaged just under an inch for a smaller fifty-shot sample. We were very pleased with this, because the rifle is accurate, reliable and works with anything we have tried in it.

So, the moral is, you can have an accurate .22 autoloader. If you don’t want a heavy rifle or don’t want to spend a tub of money on a heavy custom barrel, reline it (and don’t tell anybody). Let them think you have one of those “rare” factory autoloaders that happens to shoot well!

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