Advantages / disadvantages of the "open slide"-design

[carguychris]

I can't comment on the BDA 380* vs. Series 81 reliability question, as I don't have a BDA, however...

If I understand this correctly,,,
They are the same pistol except for the open slide.

The BDA 380 also has a spur hammer and a slide-mounted decocker/safety that drops the hammer to an intermediate "quarter-cock" position rather than all the way down like the later F/FS series Berettas. Based on handling several BDA 380's, I believe that this position is lower than the half-cock notch on the no-suffix/B/BB Berettas. The BDA 380 will only drop the hammer all the way against the slide if you dry-fire it. Also, as I understand it, the BDA 380 lacks the trigger-actuated firing-pin block of the B/BB/F/FS Berettas.

Yeah, I'm nitpicky.

*FOOTNOTE: Speaking of nitpicky, I prefer to always use the "380" name, as Browning also used the BDA moniker for DA/SA variants of the BHP in certain markets, and on the SIG Sauer P220 during their brief stint as that company's U.S. importer in the late 1970s.

 

[Will-j]

"ported slide"

WALT; CRYO 419.... I questioned Glock about he same thing with my G35back in '02-'03. Glock said the opening was to lower weight and keep [Slide Density Momentum] relative to the shorter models so as to not have different weight 'recoil spring poundage', and something to do with timing. Sounded like Greek BS to me, but, I figured it was to keep the weight of the longer slide in check with the shorter ones.
But, if you wanted to get a ported after-market barrel, you'd already have the slide already taken care of.
That's what I was told. Just sayin'
WILL

 

[Limnophile]

I read somewhere that the Beretta open slide design was intended to increase ejection reliability. From what I've read about the upcoming US Army modular handgun competition, an open slide is now a negative feature, because recent experience in desert environments show that such a design allows the ubiquitous sand to get in and foul the action.

I think the Beretta design dates back to the late '40s, and the thought is reliable ejection can be accomplished by means that don't leave the innards so exposed to environmental contamination.

 

[DAVID NANCARROW]

I don't know about improved ejection, but the only disadvantage which might come into play is that one would have to use a slightly heavier recoil spring than if it had a solid slide due to the weight loss. Not that they put a spring heavy enough to cause an issue. I will say that I've never had an ejection issue with my Vertec, but I cannot attribute it to the open top slide.

I understand that one of the field military tests for the M9 slide is to tap it while off the frame to see if it "rings." If it doesn't, the slide has allegedly developed a crack.

 

[rt11002003]

My Beretta 84FS and my Browning BDA have much in common; and, several differences. A quick glance can confuse one as to which is which. For some reason I seem to shoot the BDA better. I wanted NIB guns and could only find them in nickel. I prefer the appearance of the 84FS.

The open slide doesn't seem to be different when operating. It did "bite" the palm of my hand when cleaning it the last time; too much hand in that large opening.

 

[Walt Sherrill]

I read somewhere that the Beretta open slide design was intended to increase ejection reliability.

I think I mentioned this earlier. I don't see HOW an open slide can have any role in ejection-related reliability.

When slide moves back the extractor draws the spent round out of the chamber.

• If the round isn't pulled cleanly out of the chamber by the extractor it's either still in the chamber or left loose in the chamber area, laying on top of the magazine.
  
• If it's still in the chamber, the open slide isn't going to do a thing. If it's laying loose in the chamber area on top of the mag, the slide will be moving so fast, trying to feed the next round, all you're going to have is a jam...

Maybe something else is going on that I don't understand... but otherwise, I don't see how that open slide can do much to improve ejection reliability...

 

[Gats Italian]

The open top slide aids in ejection by sporting the biggest ejection port for 9mm cases you will ever see.

On closed top autos, the size and shape of the ejection port is critical to flawless ejection. With a CZ-75 for example, I have seen weakly ejected cases, (from sticking momentarily in the chamber, or an underpowered round providing an insufficient recoil impulse, etc.), fail to clear the smallish ejection window cleanly, bounce back, and jam the pistol.

Never seen that particular jam on a beretta 92 unless a nearby obstacle to the flying brass was the culprit.

 

[Limnophile]

Walt,

Here is a quote from an October 2011 story about the role of the M9's open-top slide in the pistol's reliability:

The M9 has been accused of being less reliable and less durable than other pistols in its class. This is simply not true. The open-top slide, while it may allow a lot of superficial dust and sand to “stick” to the weapon, is one of the features that makes it so reliable. It is much more difficult to “bind up” than other pistol designs. The M9’s slide is “self-regulating” meaning during the firing cycle, some rather violent forces act to expel any trapped foreign debris in the action.
-http://www.guns.com/review/2011/10/28/coming-out-in-defense-of-the-beretta-m9/

Nothing specific, unfortunately. I don't recall hearing complaints about the M9, other than typical 9-vs-.45 stuff, until it went to war in desert environs. In every article I've read about the promised Army Modular Handgun competition, the open-top slide is vilified.

 

[tipoc]

I don't recall hearing complaints about the M9, other than typical 9-vs-.45 stuff, until it went to war in desert environs. In every article I've read about the promised Army Modular Handgun competition, the open-top slide is vilified.

Let's see. The 92 entered U.S. military service in 1986 or so. Went to teh invasion of Panama. The first Gulf war began in 1990. The M9 went there. Went to Somalia in 1992 as well. Then back to the Second Gulf war. In all of that the biggest complaint was the bad magazines that were bought aftermarket by the Army.

So in 25 years the U.S. military has used the M9 in the dust and dirt of north Africa and the mid-east. The result of that is they ordered many more M9s. They have not had an official complaint about the gun in sand.

The complaints about the open slide design have appeared in some articles discussing the possibility of a new handgun for the U.S. military. But they have not come from officially the U.S. military.

Given that the 92 and it's open slide predecessors (the Helwan for example) have served in the mideast in just about every nation there (Israel to Tunisia) I'm willing to say the open slide ain't a big disadvantage in the sand.

You can scroll down here and see a few of the dusty places that it is the service sidearm...

http://en.wikipedia.org/wiki/Beretta_92

The open top slide aids in ejection by sporting the biggest ejection port for 9mm cases you will ever see.

That's about right.

tipoc

 

[Walt Sherrill]

The open top slide aids in ejection by sporting the biggest ejection port for 9mm cases you will ever see.

If the round hasn't been caught by the extractor, it's not being going to be extracted or ejected. The open slide doesn't help there.

If it has been caught by the extractor, it will have moved back with the opening slide, and the open area on the top of the slide is functionally meaningless (with regard to extraction or ejection.) The open slide doesn't help there.

If the spent case is partially extracted (the extractor loses its grip), you're still going to have a collision with the next round being pushed out of the magazine and fed to the chamber; you'll have something like a "stovepipe" jam and all of that will be happening near the breech area, as the slide closes -- and not near the open part of the slide. The slide will be moving far too quickly for the shooter to flip an un-ejected casing away... The open slide doesn't help much there, either.

I may be wrong --but I would argue that guns, when they cycle, don't work in a way that the Beretta's open slide can have much role in ejection-related issues.

Here is a quote from an October 2011 story about the role of the M9's open-top slide in the pistol's reliability:

Could be that it plays some role in overall reliability. But I'm not sure that "binding up" has anything to do with ejection reliability.

Just the fact that junk might not accumulate inside the slide in bad conditions might be helpful. That said, there's still room under the barrel for junk to accumulate, and it's just as easy for the junk to get in there with the slides moves to the rear as with other guns -- and easier, when the slide is forward. I've never heard of problems with the open slide.

The only complaints I've heard about from guys who have used them in combat had to do with magazines -- and some of those weren't factory-issued mags, but later, government-issued replacement mags.

 

[tipoc]

Here is a slo-motion vid of the 92 extracting and ejecting. We can observe.

https://www.youtube.com/watch?v=9eT2OststG0

If the round hasn't been caught by the extractor, it's not being going to be extracted or ejected. The open slide doesn't help there.

If the case has not been caught by the extractor on any gun that has one it won't help ejection on any gun. So for purposes of this discussion I don't think that point is a useful one.

I think that if we look at the video (there are others like it) we note that the top of the slide is open where the round is ejected. We also see that the great bulk of the open area of the slide forward of that point plays no role in ejection as the slide does not retract that far for it to play any role.

The trend over the years has been towards larger ports. the original port on the 1911 has been enlarged and those on the Glock, Sig and M&P line, etc. as enormous by comparison to older designs. This helps to increase reliability of the gun by aiding in clean ejection.

The wide open area of the M92s slide makes for a very large ejection port in that area that it matters to clean ejection.

I think that the open slide design plays little role beyond that area one way or the other.

tipoc

 

[Gats Italian]

Of course you didn't bother to tangle with the issue I identified.

Ammo can be inconsistently loaded. One way this manifests itself is how positively the recoil impulse manages to impart rearward momentum to the slide.

In the case of an underpowered round, it can still facilitate proper function and not see the case energetically tossed clear of the ejection port.

The ejected case from a Beretta 92 doesn't have to have the precise ejection timing for a case to clear a little window cut into the slide. It can weakly eject at nearly any angle and the spent case will clear the chamber area.

 

[Walt Sherrill]

Of course you didn't bother to tangle with the issue I identified.

Ammo can be inconsistently loaded. One way this manifests itself is how positively the recoil impulse manages to impart rearward momentum to the slide.

In the case of an underpowered round, it can still facilitate proper function and not see the case energetically tossed clear of the ejection port.

The ejected case from a Beretta 92 doesn't have to have the precise ejection timing for a case to clear a little window cut into the slide. It can weakly eject at nearly any angle and the spent case will clear the chamber area.

I underlined the key part of your comment, above.

If the ammo is weak but still allows proper function, even if the slide is moving a bit more slowly, the round is still being held by the extractor against the breech face until it hits the ejector. The speed of the slide isn't going to change much about what is purely a mechanical process -- It's not a TIMING issue.

If the round hits the ejector everything is lined up properly for ejection and ejection will likely happen -- just not as robustly or predictably as when the slide is moving with a higher speed. I would argue that the larger ejection port adds little or nothing to ejection process.

If the slide is moving so slowly that the ejected round doesn't clear the chamber area, it's also possible that the slide won't have enough force to strip the next round and feed it into the chamber -- and then you've either got to clear a jam or manually push the slide closed.

.

 

[DAVID NANCARROW]

I fail to see how an open topped slide is going to help a weakly loaded fired case eject. If the round has sufficient power to extract the empty case and strike the ejector, it still clears the ejection port at the same angle-just not with the force that one would expect in a higher pressure loading. The ejection is assisted by the next round in the magazine pushing up-that part of it would be a timing issue, controlled by the magazine feed lips.

I have loaded powder puff loads for my lady when she was just beginning to learn how to handle a pistol. These loads were exceptionally weak with the empty brass falling about 2 feet to her right side. In no way did the angle of ejection change, just the distance the empty brass flew. BTW, these loads were run in a Gold Cup Trophy Match 45 ACP, a closed slide. IIRC, the load was 4 grains of Accurate #2 behind a 200 grain LSWC and OAL at 1.250". All I expected her to do with the load was to feel the trigger and get used to the slide cycling. We ran a few hundred rounds of that setup and everything functioned well.

I am not down on open topped slides vs closed, but I really do not see much if any advantage.

 

[btmj]

The evolution of pistols has lead to larger and more streamlined ejection ports. Compare a WWII 1911A1 to a modern 1911. Compare a SW 59 to a SW M&P. Compare any pistol designed before 1970 to any modern pistol, and the large profiled ejection port is one of the most obvious differences. A small ejection port requires everything to go just right, while a large streamlined port allows some "slop" in the way the gun cycles and the cartridge ejects. It is nonsensical to argue that an enlarged, profiled ejection port is not a significant factor in the pistols reliability. If it weren't, why would sig, glock, walther, HK, SW, ruger, springfield, colt, CZ, Taurus, keltec, Wilson, kimber, etc all go the trouble of making an enlarged streamlined ejection port.

The 92 open slide is simply a very very large ejection port.

 

[Walt Sherrill]

... It is nonsensical to argue that an enlarged, profiled ejection port is not a significant factor in the pistols reliability. If it weren't, why would sig, glock, walther, HK, SW, ruger, springfield, colt, CZ, Taurus, keltec, Wilson, kimber, etc all go the trouble of making an enlarged streamlined ejection port.

Couldn't we use that SAME LOGIC to say that plastic grips or polymer frames are significant factors in pistol reliability? I would argue, however, that just because it seems intuitively obvious that the Beretta's open slide (your "larger ejection port") would aid ejection, thinking so doesn't make it so.

Can you offer us some evidence that a profoundly larger ejection port (like that found in the Beretta) has made THAT weapon more reliable than all of the other guns you've mentioned?

All of the guns you've cited above are generally considered very reliable weapons, but NONE of them has a VERY LARGE (Beretta-like) ejection port. it would seem logical, given your assertion above, to assume that the Beretta would almost have to be SIGNIFICANTLY more reliable than the other guns if ejection port size is really all THAT important a factor in ejection reliability. IS IT?

With a locked breech gun, when a round is fired, the slide and barrel move to the rear, and then start to separate. The empty cartridge is held in the chamber and against the breech face until pressure drops. With some guns an extractor isn't even used. With all of the other guns you mentioned as the slide moves back, the smaller (than Beretta) ejection port moves, too! That port is always where it needs to be and if the designers have made it big enough in the first place, and the round works as it should -- it really doesn't need to be much bigger! If the pressure from the fired round is sufficient to hold the round in place, that spent casing is going to go the rear and it's going to hit the ejector and flip out, somewhere.

If something happens during the firing cycle, like a grossly underpowered round or a ruptured case, and the round doesn't make it to the ejector, it's going to stay in the in the chamber/feed ramp/mag area, as there's not really anywhere else for it to go: the explosion of the round started the casing moving to the rear (along with the slide and barrel) and there's not much way for it to go in any other direction! It's unlikely to flip forward, which would be necessary for that open slide to be a factor. The magazine and the next round (ready to be stripped) are going to keep it the spent casing from going down very far.

If the fired round is underpowered or has ruptured, the slide isn't going to cycle properly anyway, and things are going to quickly come to a stop: there'll probably be a jam as the next round (if the slide can strip it) tries to enter the same relatively small space.

I would argue that main reason the VERY LARGE Beretta ejection port isn't going to be play too big a role in ejection reliability is that the round really won't leave the rear of chamber and breech area unless it gets kicked out by the ejector.

.

 

[DAVID NANCARROW]

If it weren't, why would sig, glock, walther, HK, SW, ruger, springfield, colt, CZ, Taurus, keltec, Wilson, kimber, etc all go the trouble of making an enlarged streamlined ejection port.

Look up the Petter improvement to the Browning patent for recoil operated pistols.

The reason pistols such as SIG and Glock have the oversized ejection port is the Petter improvement did away with the internal slide lugs of the 1911 and used instead a squared off barrel at the chamber to fit the ejection port. This accomplishes the same thing as the original internal slide and barrel lugs. This is really more of an ease in manufacturing than anything else, and has not one single thing to do with more positive or reliable ejection.

The US military used the small ejection port 1911/A1's for a few years if I recall correctly, and without issue even when they were shot to very loose fit. In fact, about 70+ years without an ejection problem inherent in the design. So long as the relevant parts are within military spec, it keeps doing what it was designed to do.

If anything, and this is only theoretical, the "very large ejection port" on the Beretta compromises the strength of the slide, although it doesn't seem to cause any day to day reliability problems. The top of the slide in a dropping block action doesn't lock the barrel at the top as a swinging link does, so there is no real need for metal to be there. The original design, the Walther P-38 also has an open top design.

I am still trying to understand how an open top slide is going to affect ejection in any meaningful way? The ejector, at least in my Beretta is fixed, and is not capable of adjusting its location. It depends entirely upon the slide retracting far enough for the empty case, held by the extractor, to strike the ejector with enough force to send it on its way.

I have no doubt that if someone made a closed top slide with an adequate opening for ejecting brass for a Beretta that the pistol would function. The only change might be to install a lighter recoil spring to compensate for the heavier slide.

I think its interesting that most of the recoil operated pistols use the Browning design or the Petter Improvement to the Browning well after the patents on all of them expired a very long time ago. Having that choice, most manufacturers stay away from the dropping block.
Manufacturing ease? That would be my guess.

 

[44 AMP]

Couldn't we use that SAME LOGIC to say that plastic grips or polymer frames are significant factors in pistol reliability? I would argue, however, that just because it seems intuitively obvious that the Beretta's open slide (your "larger ejection port") would aid ejection, thinking so doesn't make it so.

I suppose you could use the "same logic" to argue anything, but that doesn't mean you would be correct.

I think plastic grips or polymer frames are more like radial tires. They may give you a better "grip" on the road, they may give you better gas mileage, but they have NOTHING to do with how the car engine runs...

I think the belief that an open slide is an advantage to positive ejection simply comes from the general attitude that, if something is good, then more of it must be better.

And, while true for some things, it is not true for everything, and even when it is true, it is often not a matter of a direct arithmetic progression. It can also be a direct progression, but only apply over part of the possible range of outcomes, as well.

thinking it is a constant linear relationship leads you into the trap of extremes.
All auto pistols require some clearance (distance) between the slide and the frame, in order to function, right? And if more is better (an assumption) then the most reliable pistol possible would have the slide miles away from the frame!

IT is possible that the open slide design might have some slight statistical (mathematically definable) advantage, but if it does, it is either not easily quantified,, or is so small as to have no practical effect.

Once you have enough, having more doesn't necessarily get you improved results.

 

[Walt Sherrill]

I suppose you could use the "same logic" to argue anything, but that doesn't mean you would be correct.

I think plastic grips or polymer frames are more like radial tires. They may give you a better "grip" on the road, they may give you better gas mileage, but they have NOTHING to do with how the car engine runs...

That wasn't a serious argument -- just an example of making a claim without any supporting evidence.

From a different perspective, the "plastic grip/polymer frame" claim was also a version of the kind of argument that gives the statistician's or scientist's headaches. They will immediately point out that CORRELATION DOES NOT IMPLY CAUSATION.

Just because a trait or mechanism is present when something happens doesn't AUTOMATICALLY mean that the trait or mechanism caused that "something" to happen. Thus far we have only claims of improved ejection performance but no evidence that the claims are based on fact. (They may be based in fact, but the those facts are not being seen or shared.) Even if we see enhanced ejection reliability in the open-topped Beretta slides, we don't know for sure that it's due to the open-top slide, or something else, like a better extractor design -- until those other variables are also examined.

Beretta claims on its website that "the open-slide design practically eliminates 'stove-piping' and helps flawless cycling and feeding even after thousands and thousands of rounds." In my experience, if the extractor loses it's grip on that spent round, the casing is still moving to the rear and hasn't really moved away from the standard ejection port area of the slide. If there's enough speed and pressure, the round might still eject. If it's not moving fast enough or not positioned properly it could go astray.

If that happens, the slide is already started to change directions as it strips the next round from the mag and moves it forward. That is where and when the stovepipe problem generally occurs -- at the chamber end of the barrel, when spent case and live round collide, as the slide (and then the barrel) move forward. It seems to me that at that point, the open slide can play almost no role in preventing stove-pipe jams. (That said, I'll be the first to admit there may be something I'm overlooking, but it's not because I haven't tried to see it. I acknowledge that I'm still a student on this general topic, so I welcome correction/education if I've misunderstood or misrepresented what's happening.) It could be that their approach has eliminated "stovepipe" jams but just given us a different kind of jam... not explained.

I've owned several Berettas (92s including a Vertec, and a 96), and I don't remember having stovepipe problems with any of them -- probably because they were all NEW and unlikely to have damaged or weakened extractors or other problems caused by wear. But the same is true of every NEW gun I've purchased -- including SIGs, Glocks, Steyrs, CZs, S&Ws, different 1911s, and even five different Kel-Tec guns!!

.

 

[Limnophile]

Walt,

You could ask Beretta USA directly: http://berettausa.custhelp.com/app/utils/create_account/redirect/ask.

Let us know what they say.