The Mystery of the Beretta 391 Series Shotguns
When it comes to gas-operated semi-auto shotguns, few lines of shotguns have distinguished themselves more than the “300 series” Beretta self-loaders over the years. It was the Beretta 302 / 303 that provided relief for Browning after the poor sales of their B-2000 autos. (Although the 20 gauge B-2000 shotgun was and is a fine autoloader.) Along with the Browning B-80 and Beretta A303 we saw the action that successfully challenged the Remington 1100, the proliferation of the Mobil screw chokes, still one of the most popular factory screw chokes ever introduced, and the popularity of buttstocks user adjustable for drop by means of shims.
And now, the mystery begins. What’s wrong with an A303, anyway? Was the 390 an improvement, or an advance to the rear? Is the 391 better than either, or worse than both? Now that the 390 is back in the form of the Beretta 3901, is that better than a 391, and if so, why? There is no easy answer; that’s a good thing for mysteries, of course.
The “problem” in large measure revolves around shooting style considerations, load variations and the use of steel and other no-tox shotshells. Fundamental to gas auto operation is pressure past the barrel ports. MAP has little to do with it, as peak pressure occurs inside the shot shell hull itself, not downstream across the gas ports. Peak pressure has nothing to do with recoil and professional ballisticians can tell you that three, four, or even five thousand psi variance can be created just by changing the brand of shotshell primer.
This complicates shotgun design, as today the traditional notion of 3/4 ounce 28 gauge, 7/8 oz. 20, and 1-1/8 ounce 12 gauge standard loads has been altered. Apparently no standard load satisfies segments of shooters today; we want to shoot 28 gauge loads out of our 12 gauges because of our eternal terror of recoil, or we want to shoot 10 gauge loads out of that same 12 gauge as well all know it take hundreds of pellets to kill a turkey, not just one. Or so we believe. Marketing departments have screwed up common sense, or at least taken great liberties with it. A three inch shell must be a “magnum,” even though a 27 gram 3 inch shell is involved in the evolution of the current 391 shell carrier. If all this sounds confusing, it is because it is.
I’ve owned dozens of A303’s, B-80’s, 390’s and 391’s. Let’s start with what is "wrong" with the 302 / B-80 / 303 platform, the answer being not a thing. It is, in my view, the simplest and best field gun action of all of them. The B-80 / 303 scatterguns are easy to clean and very easy to work with. Changing from 1-1/8 ounce loads to heavy three inch shells is a momentary task, with a quick and easy barrel change. As long as we have some clue about what we want to shoot, there are no issues. The problem is, of course, is that many of us are decisionally challenged about that.
The 303-esque action is non-compensating. The more gas flow through the ports, the higher the bolt speed. The faster we drive the bolt, the more stress it takes to the point where the 1-1/2 ounce “baby magnum” loads can peen the back of the receiver. Too lazy or two cheap to change a barrel, we still search for the ultimate crescent wrench of shotguns, with no adjustments. It doesn’t exist, of course, but that doesn’t stop us from trying.
So, enter the A390, the gas action that does compensate for more or less gas across the barrel ports with a secondary bleed. A simple addition of a flange and spring in front of the barrel gas piston housing does the trick. A gassy shell has the excess gas bled off around the flange, and now we have more flexibility with the same barrel. Optimal bolt speed can be further dialed in by switching out secondary gas bleed spring of different strengths. Cole Gunsmithing offers these and they work well. The stiffest springs allow no secondary gas venting at all, so those wanting 20 gauge payload reliability (7/8 oz.) can have it. A softer spring with very quick collapse allows the use of heavier, gassier shells without excessive bolt speed. A bit more complex, no better than a 303 when used within design parameters, but more versatility that is what we say we prefer. The A390 was and is an excellent design in form and function. Thus, you might think, “that would be that.” Well, it wasn’t, at least with the introduction of the 391 series.
The 391 has its gas springs and “system” attached to the barrel. The “why” considering the increased complexity, tooling costs, engineering costs and other R & D expenses associated with the 391 gives cause to wonder what was so badly broken with the 390 that needed fixing, or what the great commercial appeal of the 391 was supposed to be to deserve this new treatment. A mystery, indeed. Is the 391 any better at all than what it replaced? Is it better than the "new" 390, the 3901?
The answer is not as easy as you might think. If all shooters were clever enough to shoot 1-1/8 oz. 1200 fps lead loads, or anything reasonably close, then there would be little basis to believe that the 390 / 3901 (much less the 391) is anything but a needlessly more complicated variation for variation’s sake inferior "improvement" to the 303. I have a personal B-80 12 gauge with over 100,000 rounds through it with no major parts replacement in all this use. The final version of the 300 series, the A304, is not available (that I know of) in the United States.
Apparently, that’s not good enough for many prospective buyers. Many of us feel we need “3 inch shell capability,” even though many thousands of three inch chambered Beretta’s have never seen a three inch shell in their lives and likely will not. It seems to be part of the human condition to want things that we never use.
For those that wanted, or think they wanted, more versatility without changing barrels, the A390 was a great success. I still own two semi-hump alloy receiver A390ST Gold Mallards. With the addition of the secondary gas bleed spring and flange beneath the fore end nut, we have a tunable action without drilling out ports or changing barrels. Again, you might think “that was that.” Well, apparently the few extra parts that give the 390 its versatility are the source of perceived problems. Shooters don’t like to clean their guns and more often than you might think lose the couple of extra parts that make the 390 a 390; the gun fails to cycle without the secondary spring flange and the owner’s manual was never read and is now nowhere to be found. Comparatively few shooters tune their bolt speed and resultant ejection distance, or replace their stock springs as regular maintenance. So, we get “jammers” as the 390 doesn’t work well with missing parts and if neglected long enough, excessive bolt speed can peen the back of the receiver. At long last, we discover the reason for the 391.
The 391 has its gas system spring attached to the barrel. As there is no loose spring, shooters have a tougher time losing it. Shooters that fail to maintain their 391’s can go a very long time, as the addition of a plastic recoil buffer at the back of the receiver inhibits peening due to excessive bolt speed with a worn recoil spring. The initial recoil buffers were problematic, though, a situation that has been long ago resolved. The recoil buffer is what Beretta calls a “sacrificial part.” This is common engineer speak for a part that wears and requires periodic replacement. The “sacrificial” bit just means that it is more desirable to replace an inexpensive part that you plan to replace as opposed to an expensive part you do not, in this case a battered receiver.
Beretta’s recent addition is a toothed or serrated 391 gas piston that lets the gun function about twice as long without cleaning. For those who won’t service a semi-auto until it fails to cycle, the 391 is far more tolerant of neglect and abuse. It still does not make the 391 a better or more desirable field gun, however.
There is more, though. The 391 has a very complicated (or sophisticated, as you wish) fore end nut full of parts. It practically defines the term "contraption." Yet, there is a reason for this. The fore end nut when tightened down fully (or excessively) on a 303 or 390, cranked down like you would the fore arm nut on an A-5, captures the 303 / 390 barrel. Beretta discovered that with extremely high-volume competitive shooting, the captured barrel when heated to “burn your fingers through the wood” levels also exhibited a change in point of impact. The nut captures the barrel, but the barrel grows and lengthens when super-heated and the resultant “sway-back horse” look of the slightly, temporarily deformed barrel, while not readily perceptible to the naked eye, may yield a POI change. The 391’s floating, springed forearm nut accommodates barrel lengthening due to temperature change with no point of impact shifts. Perhaps the crazy Italians were not so crazy after all?
Well, that is Beretta’s assertion, anyway. This mysterious point of impact shift is nothing I’ve witnessed, nor is it plausible as to having any practical implications one way or another. If indeed barrel heating was contorting your barrel like a piece of a piece of spaghetti due to the for arm nut pressure, the more clever competitive shooters would loosen the forearm nut a couple of clicks rather than calling for this nasty little seven part nut (more parts than the 303’s entire gas system!). It’s Beretta’s story, though, and they are sticking to it, or stuck with it as the case may be.
Moving on, we have the notion of “391 Bent Carrier Syndrome” resulting in jamming that is “solved” be replacing the flat 391 carrier with a bent, “better” 390 shell carrier. This is a mystery as well. There is a reason for the 391 style carrier, having its roots in light payload (27 gram) three inch shells favored by some European competitive shooters. A long shell with a long wad with a lead payload at the crimp end of it is an unbalanced, nose-heavy shell. This new (foreign to most American shooters) load can be problematic in the 390, so the 391 bent carrier was introduced to take care of that isolated issue. It created its own set of mysteries.
The very early 391’s used 390 carriers, exhibiting the unbalanced shell difficulty just noted. So, the “Generation One” 391 flat carrier was introduced. Problem was, the tooling was bad and the die that formed the “Stage One” carrier sometimes deflected the next shell to be loaded to the right, resulting in a failure to feed, the very thing the 391 carrier was designed to address. Bad tooling, warped carriers (this had nothing to do with the design, but the manufacture) gave the 391 carrier a bad name in some circles that still persists. Well, finally, the 391 “Generation Two carrier” with new tooling was introduced and that is what is prevalent today. still a 391 flat carrier, but made as originally intended with appropriate tooling. The two guys in New Mexico that shoot 3 inch, 27 gram shells will be delighted, of course.
While the 391 is more of a pain to clean, it is far more tolerant of going a very long time with no attention at all. That’s the trade off against the 390; harder to clean, but needs it less. It is more complicated, but harder to lose integral parts.
As a field gun, my preference is the 303 / 304 series. Again, I wish the 304 was commonly available in the U.S. Both the 303 / 304 and the 390 could be updated with the spinning gas piston, to the benefit of both models.
That is the resolution of the 391 mysteries, at least for now. Beretta adds their own special brand of mystery by naming their A391 Xtrema2 a “391,” even though it is an entirely different rotating bolt, "O" ringed piston gas action that is not a part of the 303 / 390 / 391 lineage at all, but a new action offered to accommodate 3-1/2 in. loads.
So, after all this (more than most normal people care to know), the consumer is left with choices. For most shooters, the 391 is of no great tangible benefit over the 390 and the 303 that preceded it. In fact, the made (or assembled) in the US 3901 Series is the 390 brought back and is a more affordable shotgun than the 391, with no less field utility.
As to the eternal mystery of what is “better,” only the individual can decide that. There is, of course, no “better” just “more better” for the individual application. For me, there is nothing better than a 303; different, but hardly better. Target shooters may well opt for the 391, value shooters for the 3901 (390).
I hope this explains some of the differences, if not completely all of the mysteries. Why I just penned over two thousand words on Beretta 300 series gas autos is a mystery to everyone, including myself.
Note: Full length reviews of the Beretta A390/3901 series shotguns can be found on the Product Review Page.
Copyright 2008, 2012 by Randy Wakeman. All rights reserved.