Notes On Glock Barrels

We have heard it before, "Glock Perfection." Glock pistols of all models have seventy five per cent parts compatibility. The compatibility claims I will sign off on as correct but perfection is beyond mortal kin. Part of gunsmith experience is fitting barrels and the Glock has its own unique parameters. I have fitted a number of Glock barrels over the years and my experience has been generally good. Occasionally there have been lowered expectations simply because the customer purchased an inexpensive barrel.

There have been less than perfect results but we have also enjoyed exceptional results from the better breed of barrel including Jarvis, Wilson Combat and Bar-Sto Precision. I have encountered less than perfect jobs by amateurs but I have also observed exceptional fitting with custom barrels. The important point is that in every instance I have produced good results and a reliable handgun when I had quality parts to work with. Accuracy is often increased.

The results with the Bar-Sto barrel in particular has been excellent. In simple terms the addition of a custom grade barrel coupled with well designed aftermarket sights will often turn the Glock into a 50 yard pistol while the piece is arguably a 25 yard pistol as issued. Some shooters decide upon a custom barrel whether or not they are able to utilize the additional accuracy potential. There are other reasons for changing the Glock barrel. I do not think a worn out barrel is a consideration.

I have examined Glock barrels at the 20,000 round count and the barrels are still serviceable. Many of these high round The case on the right burst in a Glock with unsupported chamber. The case on left was an over charge fired in a Kimber 1911. Neither is a good place to be. count pistols remain reliable and accurate enough for service use, despite having been fired exclusively with jacketed bullets. There are three main reasons for fitting a custom barrel to the Glock.

First is the customer’s desire to use lead bullets. Factory Glock pistols use polygonal rifled bores. The primary difference is that the bore is rifled with hills and valleys that are quite smooth rather than the traditional lands and grooves. This results in little friction and generally higher velocity than conventional bores of a similar length. Accuracy potential is claimed to be high due to the prospect of little bullet deformation. However, there is no place for lead fouling to accumulate.

Sport shooters using cast lead bullets for economy cannot use great quantities of lead in the Glock barrel. There is also the fact that the Glock has a sharp transition from the chamber to the leade, or beginning of rifling, which also accumulates lead. This lead build up may prevent the pistol from fully closing and the resulting build up will allow the pistol to fire when not locked in battery.

While the Europeans may think we are mad for using lead bullets this is the only way for the shooter of average means to afford to fire the piece in the quantity demanded for proficiency in competition. The Glock barrel as supplied from the factory also has an unsupported chamber in order to insure feed reliability. Almost every aftermarket barrel will offer a more fully supported chamber. The second reason for replacing the barrel is a search for increased accuracy. A custom grade barrel will increase accuracy.

This is partly due to careful manufacture and partly due to superior fitting. The third reason is for a caliber change. Often a shooter will prefer another caliber or simply wish to use several calibers in their Glock. You may convert a .357 Glock to .40 and vice versa or convert a .45 ACP Glock to .400 Cor-Bon. There are other conversions as well. The majority of Glock barrels sold are drop in barrels that are designed to fit to factory specifications. These

Above left and When you understand the proper fit and function of a Glock barrel, barrel swaps are straightforward operations. The hood is easy enough to fit and the barrel lugs seldom require attention. The bottom foot controls lift and is similarly trouble free. are most often purchased in order to allow the Glock shooter to use lead bullets. After using many of these barrels I have to make a few comments on handloads.

It is difficult to order a custom barrel and then tell a shooter who has spent good money on custom loads that his handloads are not up to par. We must understand handloading and ballistics in order to make that judgment. Just the same in proofing and fitting the custom barrel we should use a proven factory loading of proven reliability and accuracy. This means a load that is not too light or too heavy but with sufficient momentum to function in the pistol.

I have taken to keeping a good stock of Fiocchi USA ball ammunition for this purpose. I use the 124 grain 9mm, 180 grain .40 and 230 grain .45 ACP. In the occasional 10mm pistol I use CCI Blazer loads when available. I have used Speer Lawman .357 SIG loads for the same purpose. I proof the handgun with these ball loads before progressing to lead or hollow point bullets. Once the pistol is proofed with these loads a malfunction with handloads will be a qualified malfunction related to the ammunition.

That being said handloads may be produced that are at least as reliable and more versatile than factory loads once the pistol is proofed. Recently, I worked with a .40 caliber Glock that simply would not function with any standard handload. I was using the proven Zero Bullets 165 grain FMJ over enough Tite Group powder in Starline brass to demonstrate 900 feet per second. The new barrel seemed to be fitted OK but the problem was insidious. About every tenth round would not properly cycle.

The shooter had dropped the overall length of the cartridge, although he assured me he was in safe pressure limits, but the problem remained. The bullet taper cannot be allowed to breach the cartridge case mouth and deep seating bullets is counter productive to feed reliability. When manually operated the cartridges fed fine. These cartridges passed the Brownells Go/No Go gauge and they fit perfectly when dropped into the barrel. Even with the barrel tilted they still worked as far as chambering.

Some of the failures presented the bullet nose at a thirty degree angle to the barrel chamber. Yet every time the slide was manually racked the loads functioned. I made certain the spring was a full power Glock recoil spring. A possibility was that the pickup rail picked the cartridge up at the extractor groove rather than the rim. This would result in the cartridge not getting a full travel. While a good bet, this hypothesis did not pan out.

Often a high capacity magazine that extends past the grip frame will give trouble but this was not the case either. I did another firing test with a slightly different load and encountered the same problem except that now the cartridge did not always feed when I dropped the slide manually. By holding the slide a bit further to the rear and releasing the slide the rounds fed every time. With all else failing to resolve the issue I decided to address the chamber.

As it turned out certain dimensions were tighter than the original Glock barrel. In the end I carefully polished a rounded edge from two o’clock to ten o’clock on the chamber. I hit pay dirt with this one. The Glock ran smartly after this simple polish.

This barrel offers conventional rifling. When installing the barrel hood and the locking lugs may require attention. The Wilson Combat drop in barrel is usually just that, a drop in, but sometimes fine tuning is necessary with custom barrels. Overall, the Wilson Combat barrel is a good combination. Another drop in barrel gave considerably more trouble. Perhaps it was a gunsmith fit barrel that was mistakenly packaged in a drop in pack!

Glock frames are the same internally without fail through all generations, they claim, so the fault must have been in the barrel. Just the same, several holster makers tell me you have to know the Glock generation to get a properly fitted holster, although this does not mean effect anything internally. The hood of the suspect barrel presented no problem but the rear lug struck the frame lock bar. I proceeded to cautiously mill and file, then stone the lug. I removed 0.016-inch off the rear lug.

The rear lug then cleared the lock bar. I did not like the amount of work needed on this drop in barrel but it worked. Another experience was with a .357 SIG barrel from Bar-Sto Precision. This barrel was an eye opener. The primary purpose of this barrel was the owner’s wish to experiment with the .357 SIG cartridge back when the cartridge was new and there no factory Glock pistols were chambered for the round.

The Bar-Sto barrel was a drop in without any sort of fitting. however, we were very surprised at both the accuracy and velocity results. In those days most factory .357 SIG was no hotter than a good warm 9mm +P. The first Cor-Bon loads fired clocked 1503 fps with a 115 grain bullet. Accuracy was excellent. We fitted after market sights and the pistol often grouped five shots into less than two inches at twenty five yards, a far cry from the four inch-plus groups at 25 yards with .40 factory ammunition.

I did have to fit a heavy duty W. C. Wolff recoil spring to preserve cycle reliability. The .400 Cor-Bon conversion in the .45 Glock was uneventful as well. I have done only one, but this was simply a drop in conversion. There were no problems and the pistol simply ran as well as with the .45 ACP loads. Remember, when fitting a .400 Cor-Bon barrel to a 1911 you may have to open the feed lips of the magazine. This would not have been possible with the Glock.

Some notes on fitting procedure for gunsmith-fit and semi drop-in barrels. I first attempt to drop the barrel in the slide and frame. If the barrel does not fit correctly it is most often the barrel lugs binding. I remove very small amounts of metal from the hood area. Then I check to see if the under lug is perpendicular to the bore as it should be. If off center, material is removed from the opposite of the offending side. Look toward the muzzle to gauge right and left alignment of the locking lugs.

Off to the left, remove metal on the right. When done with the lugs, fit the barrel into the slide and check for fit. Remember to respect the locking lugs as these lugs control lift and chambering angle. The bottom foot controls lift and usually gives a good tight lockup without any type of modification. The Glock is a straightforward pistol, simple enough to work with and durable. The only common reason that you will see a Glock in the shop is for barrel work and this is the most beneficial change to it. AG