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Aftermarket Pistol Barrels: Using and fitting aftermarket barrels for pistol projects.

I am sometimes surprised by the potential of modern factory handguns. Quality handguns are very accurate, well made of good material, and offer impressive reliability. But there is room for improvement. Among them is fitting a match-grade barrel. Properly fit, a quality aftermarket barrel can considerably improve precision, with less slop and eccentric wear. This allows greater accuracy and longevity over the long run. With custom fitting by a gunsmith, looser tolerance s needed for reliability for mass production can be reduced, improving accuracy with no loss of reliability and improved wear.

Fit is more than filing the barrel until it can slip into the slide. Even if it results in improved accuracy, imperfect fitting won't yield maximum potential. The secret is taking care in fitting, being painstaking, and working slowly to achieve the best results. My aftermarket barrel preference are those from Bar-Sto Precision Machine (, 605/720-4000) as they are a family business producing excellent quality barrels since 1967. The first custom handgun barrel I used was a Bar-Sto. While the gunsmith's part is important, high-grade aftermarket barrels have features making them superior to factory production. Bar-Sto uses an eleven-degree match crown versus the factory-standard rounded profile along with more precision cut lands and grooves.

Not Just 1911s

While most of my barrel work revolved around 1911 handguns, this changed with the introduction of the Glock as the factory's polygonal rifling wasn't compatible with lead bullets. Aftermarket barrels were offered that were suitable and these conventionally-rifled barrels offer good accuracy. While there are several available, if we are going to fit a barrel we might as well go ahead and go with Bar-Sto.

Accuracy has been considerably improved in the examples I have fitted and tested. Among the first was a Glock 22. When the .357 SIG was introduced I wished to test the cartridge without obtaining another firearm and ordered a Semi Fit Bar-Sto barrel in the chambering. Glock 22s typically held about four-inch groups at 25 yards with select ammunition, with some loads turning in six inches. Adding a set of Novak sights helped practical accuracy but intrinsic accuracy was still poor. After fitting a Bar-Sto barrel, several loads averaged less than three inches. A drop-in Bar-Sto barrel for a Glock 36 ordered in ported form primarily for economy use with lead bullets seemed to lower recoil and yielded excellent accuracy. When the owner later elected to have the barrel shortened by cutting the ported section, accuracy remained good to excellent.

Match Target and Semi Fit are the two general Bar-Sto categories. Critical dimensions are oversize in the Match Targets, while Semi Fit usually drop right in SIGs and Glocks without fitting. With 1911s, some fitting is needed about half the time. Not too many years ago, I ordered Semi Fits in 9mm and .38 Super for a Colt Government Model and both dropped in. Match Target barrels for the European pistols are deliberately oversized in the barrel hood and lower lugs.

The big difference between Bar-Sto and factory barrels is in the precision of machine work. I have seen some pretty ridiculous notions regarding chambers and tighter bores that simply are not true. The fit of the barrel to the slide and the precision of the rifling is what makes a match-grade barrel. SIG and Glock pistols butt the barrel hood into the ejection port for lock up. The barrel hood of a Match Target barrel is oversized and must be filed to achieve a good fit. The process isn't complicated but you must take your time. Simply removing metal until the barrel fits and the handgun functions may suggest you have fitted the barrel. However, even if there are accuracy improvements by virtue of the precision of the barrel, a greater edge in accuracy is obtainable.


The barrel hood is marked with a red or blue Sharpie for reference prior to beginning work. Comparing a Match Target barrel to the factory barrel shows how much metal will be removed. It isn't much! Drop the barrel into the slide and attempt to lock the barrel to the slide. When the barrel is removed the marking will be smudged where the oversize barrel hood is preventing the barrel from locking up. The barrel hood is carefully filed and then fitted into the ejection port, a little at a time, until the barrel fits snugly but may be removed with just slight finger pressure. The locking or camming surfaces on the lower barrel are also marked and the barrel fitted into the frame in the same manner. Take your time, a stroke of the file at a time. This is where some misunderstand barrel fitting and simply remove metal until the barrel locks up, removing too much too soon with too many strokes of the file. Take your time on this project and understand the difference. It is rather easy to file the barrel to fit but more difficult to achieve an optimum gunsmith fit.

If the barrel easily drops into a different pistol of the same make, perhaps the fitting wasn't ideal. The fit must be tight to the individual handgun. I fit barrels until the slide has the slightest hesitation in locking. The final fit is done by heavily lubricating the handgun and firing a magazine to seat everything. It works for me, though some debate this procedure. It is similar to the break-in period of a tight match-grade handgun.

With Semi Fit barrels, the first step is to drop the new barrel into the slide and examine. SIG and Glocks usually don't require fitting with an improvement in accuracy potential. As for the amount of improvement, it is incremental in some handguns and surprising in others. Where the first generation Glocks chambered in .40 S&W would see groups cut in half with a Bar-Sto barrel and adding better sights helped more. As one shooter summed it up, this allowed the Glock to become a 50-yard gun instead of a 25-yard gun. A good SIG may see improvement from a 2.5" group with quality ammunition down to 1.5-2.0". While I use ordinary ball ammunition for function testing, Federal Match stands alone for testing Bar-Sto barrel accuracy. A handload with a Magnus 200 grain SWC over enough TiteGroup to reach 900 fps gives similar results in the .45 ACP, while Fiocchi 124 grain Extrema works well in the 9mm. There are few truly accurate factory .38 Super loads but the SIG Sauer 125 grain FMJ load gives acceptable results. 1911 dropin barrels often yield improvement of about an inch in group size. Fitting a Bar-Sto to a Rock Island 1911 is a more profound two inches over the factory barrel.

9mm/.38 Super

In factory 1911s, .38 Super has a deserved reputation for inferior accuracy compared to .45 ACP and new 9mm variants. The situation equalizes when a Bar-Sto Match Target barrel is fitted. The Super enjoyed a small but loyal fan base for years because of this. Bar-Sto begin chambering the barrel to allow the case to properly heads pace on the mouth rather than the Super's case rim, where Colt originally headspaced on the rim, a throwback to the 1900 .38 ACP. This greatly improved accuracy, taking a 4-6" gun at 25 yards to a two incher.

Recently, I've had good experience with the new Ruger SR1911 9mm, an accurate pistol with a lightweight, Commander-style frame. Ruger improved on the 1911 by changing the plunger tube to a permanently affixed rather than staked-on style. Inspiration came to convert this pistol to .38 Super. Bar-Sto did the work but their procedure is worth discussion.

The barrel hood should fit the slot in the breech face but the side should not make contact, just a few thousandths on each side. The width of this slot is 0.442" and Match Target barrel hoods are 0.451" so some fitting is needed. The barrel hood is filed until the fit is tight and the barrel drops into the slide, contacting the breech face. That is width. Barrel hood length is fitted next. The barrel will not usually travel far enough to the rear for the locking lugs to lock into the slide. The hood length of the barrel may be 1.33" and the recess in the 1911 slide is around 1.314 inch, making this close work that must be exact. 0.016" of material is the measurement. While specific measurements may differ on different 1911s, this is a good guide. The barrel hood will lock properly and just touch the breech-frame without binding. It must fit evenly. The final touch involves lapping compound and tapping the barrel in and out of the final fit.

Not done yet! The lower locking lugs much also be fitted in the Match Target barrel. When the pistol is in battery the barrel is wedged between the slide stop at the bottom and the locking lugs of the slide with no movement at all. There is a definite stop as the barrel locks. While the inexpensive 1911s just don't have it, Springfields, Rugers, and Colts do to a certain extent.

A Match Grade barrel feels and performs better. Slide stop pins are available in oversize configuration but the factory slide stop works fine. Both lower lugs must be flitted in order to put pressure on the slide stop evenly as they bear on the slide stop while in battery. Marking the slide stop pin shows how the lower lugs bear on the slide stop as the 1911 goes into battery. One lug will often show more contact than the other. File that lug until both lugs are bearing evenly on the slide stop pin. Cut the locking lugs until the slide locks up tight. For a super accurate fit the slide will require the slightest nudge to fully close when the slide is eased forward. I like this type of fit for superb accuracy, but unless you are very familiar with the process you may not achieve both good accuracy and excellent reliability.

by RK Campbell
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Title Annotation:BENCHWORK
Author:Campbell, R.K.
Publication:American Gunsmith
Date:Nov 1, 2017
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