The M1911 in 10mm: Some Special Considerations

It took quite a few years, it seems, for gun makers and gunsmiths to learn how to make the 10mm cartridge run smoothly in the M1911type pistols. This knowledge is worth remembering, however, since there are both old and new commercial 1911 pistols available in 10mm, as well as pistolsmiths’both amateur and professional’who prefer the 10mm cartridge over the .45 ACP. The first pistol chambered for the 10mm cartridge was the ill-fated Bren Ten pistol.

The Bren Ten was a commercial failure for a combination of 45 ACP (left). As a result, fine tuning of the 10mm pistol demands considerably more care. reasons, but the 10mm cartridge survived due in large part to Colt’s introduction of the Delta Elite in 1987.

Everyone remembers the problems with the first Delta Elites (they were quickly resolved), but the cures are not as widely known. (The framecracking problem was solved by adding a relief cut in the frame.) And there were and are other problems that were function-related, not wearrelated, that were common to the Delta Elite, the Gold Cup 10mm, the Elite 10mm, and various other Colt and non-Colt 1911s chambered for the 10mm cartridge. These are problems that are not common to .45 and .38 Super pistols.

In my experience, the new Kimber 10mm seems to be free of the ills of earlier 10mm 1911s, and Kimber seems to have made every improvement that was needed in the 10mm. And, to be honest, at least some of what I’ve learned about the 1911 in 10mm has come from studying the Kimber. The 10mm is a high-pressure cartridge compared to the .45 ACP, and generates much more momentum than the .38 Super.

The mil-spec chamber of the 1911 is plenty strong enough to contain the 10mm, but power is always gained at some expense and wear may be increased. Slide velocity is also increased over the .45 ACP, and some type of extra-strength recoil spring is needed. The original Colt Delta Elite used several variations on the full-length guide rod, none of which were very workmanlike, in my opinion. The plastic original type was deemed "Mickey Mouse" by writers in the popular press.

Oddly enough, in preparing this article, I could not find an original guide rod for refer-

This Colt features the shock buffer combined with a Champion full-length guide rod and a 20pound spring. ence; it seems that none of them have survived. Poor spring technology led to reliability and accuracy problems. Too light springs proved to promote inconsistent locking and resulting poor performance. A heavier mainspring than the 16-pound .45-type was needed to ensure the slide locked properly and handled the 10mm pistol’s recoil.

Some of us took a bit longer than others to understand what was needed to properly spring the 10mm. The recoil spring does not reduce pressure, but it certainly helps to contain pressure. The 10mm 1911 barrel begins to unlock after about an inch of slide travel. When dealing with heavy recoil springs, the effect of the mainspring must also be considered. After shooters realized that a 20-pound recoil spring was needed in the fullpower 10mm, all problems were not cured.

For example, if you install a full-power recoil spring in a pistol where the shooter has fitted a light mainspring in order to achieve a lighter trigger action or easier cocking, then much of the advantage of the recoil spring is negated. The recoil spring and the mainspring must match. But for many years, fitting lighter mainsprings in the .45 was considered standard operating procedure. Things aren’t quite so simple with the 10mm, however.

When a 10mm pistol exhibits function problems, the best approach is often to replace all the springs in one clean sweep. The matching of the hammer spring or mainspring with the recoil spring is almost an art form, and is not always well understood. The mainspring should be full power, and the recoil spring for the full-power 10mm should be a 20-pound spring. I recently bought a W. C.

Wolff spring set for the 10mm 1911 from Brownells. (The folks at Wolff understand the art of matching springs. ) This set has a 20-pound recoil spring and a 24pound hammer spring. But there is more to the game than controlling recoil with the hammer spring and recoil spring. Cycle reliability is also important and deserves some study. The heavy 20-pound recoil spring only changes rearward travel.

In other words, when the pistol is battering itself to death with a too-light recoil spring and we fit a heavy recoil spring, this new spring only arrests the rearward travel. Forward travel is actually speeded up. When this situation exists, a weak or well-worn magazine spring will make itself known, often failing to feed the cartridge properly on the last round. Metalform is the only source I know of for high-quality, modern 10mm magazines.

With Colt 10mm magazines, a failure to lock open on the last shot or a failure to feed on the last cartridge in the magazine is common. Match the 20-pound recoil spring and the 24-pound hammer spring with anew Metalform magazine, and you’ll solve a lot of function problems. Accuracy is adversely affected by poorly matched springs. A 10mm pistol that fires "patterns" instead of "groups" is probably suffering from mismatched springs and inconsistent lockup.

This has given the 10mm an undeserved reputation for poor accuracy. The weak springs simply don’t bring the piece back into battery correctly. While we’re on the subject of springs, your customers should be aware that heavy springs are demanding, and if the shooter is not doing his The author suggests considering future maintenance requirements when choosing a full-length rod.

AGARAD7 Armorer’s Course, AMG Version (coming directly from Belvoir)

AGARAD7 Armorer’s Course, AMG Version (coming directly from Belvoir)

part our work will go for nothing. Be certain he understands that the pistol must be held in a proper shooting grip. A limp-wristed hold guarantees a short cycle with the combination of full-power 10mm loads and heavy springs. Another factor that’s often overlooked is that the slide of the Colt Delta Elite is heavier than that of the .45 1911. This is why the recoil calculation might call for a 24-pound spring in a standard 1911, but the 10mm actually runs well with a 20-pound recoil spring.

Of course, I’m talking about using full-power ammo such as the Cor Bon 135-grain 1,450-fps loads rather than the 10mm "light" loads that are in .40 S&W range ballistically. pled with W. C. Wolff springs with good results. I don’t always use a fulllength guide rod in a .45-caliber pistol, especially if frequent cleaning is going to be required. The one-piece guide rod continues to perplex some novice shooters, and the small hole in the rod begs an explanation.

I’ve seen a number of these rods that were buggered up because someone thought a punch or nail could be inserted in this hole and the rod screwed out. Rather, the slide is racked to the rear and a paper clip or thin wire is inserted into the guiderod hole. This allows the spring to be With the full-power 10mm load, this is the preferred type. The Springfield on the left has a rather sharp-shouldered beavertail, while the Kimber on the right features the preferred style.

While fulllength guide rods are considered an unnecessary complication to some, I think they’re an asset in the 10mm. Some guide rods are more troublesome than others, but I’ve used the Champion guide rod coucompressed and the guide rod to be removed from the bottom of the slide during disassembly. Actually, I prefer the full-length two-piece guide rod. The two-piece rod requires an Allen wrench for disassembly.

The Allen wrench is applied to the end of the guide rod and the forward half is screwed out for disassembly. Another slightly different type is the recessed guide rod. With this type, a barrel-bushing wrench is used to depress the barrel bushing enough to remove the end cap. Either type is available from Brownells. I think it’s a matter of personal preference, but I believe the two-piece rod is the easiest to service. This brings me to a strange malfunction I’ve seen only with the 10mm.

Somehow, a burr can develop on the reverse plug of a 1911 equipped with a full-length guide rod. The burr can be severe enough to hang up the guide rod. I suppose this is probably related to battering. Without a spare reverse plug on the shelf, I’ve polished and re-contoured an offending plug with a Dremel tool and good function was restored. Another factor that should not be

overlooked’especially when building a 10mm pistol from parts’is comfort. Keep in mind that the 10mm has more recoil than the .45 ACP. Thus, any sharp edges, especially as found on the tang in some runs of Colts, can be uncomfortable. When choosing aftermarket accessories’even including grip panels’t his greater recoil must be kept in perspective. A raspy handle may not be ideal today, when more shooters work on a keyboard than with a jackhammer.

Another poor choice for full-power 10mm pistols is a beavertail with a pronounced memory groove. This type of beavertail will slam into the hand under recoil. A more conservative profile is indicated for the hard-kicking 10mm. Rather than a beavertail with a pronounced memory groove, a beavertail that spreads the recoil across the palm will be much better. Feed reliability is seldom a problem with the 10mm.

The long and relatively slender case of the 10mm would seem to be prone to misfeed, but it seems that all the popular 10mm bullet styles feed reliably. The issues are more related to cycle reliability. I have encountered a number of ejection problems with the 10mm. This makes sense considering the heavier springs used with the 10mm automatic. This is one of the few cases in which an extended ejector actually proves to be an asset.

Among the oddest problems I’ve ever encountered is the problem of a 10mm 1911 with ejection port flash. Sometimes, flash at the port is a problem with a .45, but the 10mm is by far a worse offender. While this doesn’t seem to be a safety issue, ejection-port flash is often accompanied by poor function. When the proper springs are fitted, ejection port flash usually goes away. I suppose the piece is firing and unlocking a bit too soon.

This seems to be the only explanation for ejection port flash, especially when we realize that the use of heavy springs most often cures this problem. One problem with the 10mm that concerns handloaders especially is damage to the ejected case, and I’ve seen some that were really chewed up. This is a malfunction waiting to happen, as the slide is striking the case before it is completely out of the slide window. There is always the possibility of a malfunction if the cartridge case is struck just right.

The ejector, it seems, is seldom at fault. In fact, the ejector is usually kicking the case out properly, but the slide is still managing to catch the cartridge case. I’ve found that tuning the extractor can help. Sometimes, I simply fit and replace the extractor with a Wilson Combat bulletproof extractor. Here again, we need to keep in mind the differences between the 10mm and the .45. The .45-caliber extractor really takes a dig in the extractor groove.

When fitting a 10mm extractor and working the small hump on the extractor body for a good fit, there are allowances to be made with the 10mm case. (I also often use the Weigand extractor-tension tool to reset extractor tension.) The 10mm should be tuned to take a little less of a dig in the extractor groove than the .45. When the extractor is properly tured for the 10mm, beat-up brass is not a problem. I recently worked with a Dan Wesson Razorback. This is a 10mm pistol with an external extractor.

When the case was withdrawn from the chamber, the tension from the extractor made removing the cartridge case very difficult. External extractors set for the .45 as this one apparently was will not function as well with the 10mm. I bent the hook of the external extractor slightly and cured this problem. A final small problem I’ve seen is with the sights on a 10mm. Set screws are more likely to work loose under the recoil of the 10mm than that of the .45.

A little extra care with the 10mm’ and possibly some non-permanent thread locker can help to alleviate this problem. While owners of the Kimber and other high-end 10mms might disagree, the M1911 is more finicky in 10 mm than in .45 caliber and certainly not as long lived. Still, with proper attention to detail, the 10mm can give the owner good service and an acceptable service life.