MachIVshooter
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Heavier slide. Remember, doubling mass at a given velocity doubles kinetic energy, while doubling velocity of a given mass quadruples KE.
Statistical Evidence That Higher Pressure Rounds Wear Out Guns Quicker
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Heavier slide. Remember, doubling mass at a given velocity doubles kinetic energy, while doubling velocity of a given mass quadruples KE.
Destructo6
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HK P2000 fed 155grn JHP.
I've seen, probably, 10 break this way, personally. One was my own, another was a dude shooting next to me (chunk went downrange), and the others were laying around before being sent back. I've seen far more pics of the same from other stations. So, not really uncommon.
It would start with a discoloration of the slide around the guide rod hole, then progress to the tang being bent forward. If not caught in time, the tang could break off and lock up the gun.
Beretta frames would crack using the same ammo.
I'm guessing that was part of the reason to transition to 180grn jhps.
Pressure on its own is pretty much meaningless. The size/shape is equally important, both for the round itself and the structure containing it. That is where you get into material stress which is also expressed in PSI which can be confusing for folks. The graph barnbwt posted is for stress, not pressure. Just knowing the pressure of a round doesn't tell you much. For instance you'd blow up a .45 Colt New Vaquero at far less pressure than a .357 New Vaquero would take.
Is that with a gun shooting normal off the shelf loads or super duper hot rounds?
I'm approaching 40,000 rounds in my plastic M&P 40 and there is no sign of wear at all. I've replaced the magazine springs once and the recoil spring once although I probably didn't need to, when I got the replacement, the slide tension didn't feel markedly different than the old one.
Maybe I need to throw this "time bomb" out the window.
Where were you technical people when Bart Bobbitt was proclaiming the evils of bolt thrust, without having the slightest clue about the loads firearms are designed to?
Pressure is pretty much meaningless until you convert it to a load. That is pounds force. Structures are built to a load and a service life. That fatique curve helps in evaluation of service life, you get the loads down, the service life does go up, all things being equal.
I don't know what design criteria they used in older guns. I am totally clueless on how John Browning sized his lugs or anything on his weapons. Modern CAD/CAM programs, like SolidWorks, stresses are displayed on screen and you attempt to design or redesign to get the stress concentrations down.
For a lightweight weapon, like a rifle or pistol, the design lifetime is in 10,000's of cycles, not 100,000's. The tradeoff is weight. Any damn fool can make a 20 pound single shot pistol or rifle, the trick is to make a 2 pound pistol or 7 pound rifle that goes bang without going Kaboom!
Walt Sherrill
Member
Justin22885 said:
I don't disagree that aluminum might wear out more quickly than steel, but as I understand it, it's not because steel is stronger, but because steel is a more resilient material. Steel can flex and bend and return to its previous state without damage. Aluminum doesn't do that well -- it just tends to break rather than flex.
It's not a question of stronger or weaker, but how the steel and aluminum handle the forces applied to them. In many respects, aluminum is stronger and lighter than steel but less resilient. That's why they don't build aluminum bridges: they can't take the flexing caused by moving vehicles and climate and winds.
Justin22885 said:
I suspect that you could creat an aluminum-framed gun with the same sort of steel insert you find in some polymer guns, and then have a gun that is as durable as most steel guns, but still weigh less. For some applications, lighter is better.
Chuck R.
Member
This is pretty much my approach, IF I mange to wear out a gun shooting it, more power to me! I'll just go buy another one.......
Chuck
barnbwt
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Sorta-kinda. Aluminum is special in that it doesn't have a "fatigue limit." IIRC, it is due to how copper in the alloys interacts with the grain boundaries (i.e. it has something to do with why the heat treats are so funky for aluminum as well). Basically, most materials only propagate cracks when repeatedly loaded when the load gets above a certain level --the fatigue limit-- and below that are essentially immortal. Design your part to get just under that limit, and it'll last centuries with care (or at least not fatigue out due to cracking), but go above that and you have to start horse trading strength for expected service life.
However, Aluminum (and also brass, I think) simply has a sloped curve that theoretically doesn't care if the stress is 1psi or 1000psi, it will eventually fatigue out. Okay, it's not quite that way in practice, but the fatigue limit is so low that for engineering purposes it isn't counted on to help service life like it can be for steel. Very important material property to know when designing aircraft fuselages that must be inflated to 7psi at altitude repeatedly, or ship hulls which must withstand wave battering at subzero temperatures (the DeHavilland Comet and Liberty Ship disasters were kind of the impetus for large scale research into this science)
The important things to take away from that chart:
-Higher stress = lower service life, and it is an increasingly rapid trend
-For steel, there is a limit below which the service life is functionally infinite
-For aluminum, the slope simply continues downward for a theoretically lower service life
-The chart only tracks the type of failure caused by stress fatigue; micro cracks present at time of manufacture being pried further and further into the part by cyclic loads
-The chart only tracks identical loads; if you mix hot/mild loads or occasionally beat your gun against a tree stump in some misguided 'torture test' the math gets much more complicated
-These curves vary a lot between materials, even between alloys. They are themselves statistically derived like all material properties and highly variable batch-to-batch. The exact nature & placement of the microcracks being propagated ultimately determines exactly when failure occurs; the chart is just a conservative estimate so designers have a rough figure to work with (for certain things like sheet metal or simple shapes, it is quite accurate, though)
-The chart shown is probably for 'sinusoidal' (smooth) loads, which will not accurately predict the impact loading seen in firearms. The relationships are the same, but the exact numbers & relationships will change for the less-predictable
Aluminum is capable of being about as ductile as cardboard, and steel as hard/brittle as glass. The main reason aluminum has a reputation for being weaker in guns is because dummies try to simply substitute aluminum parts for steel ones without redesigning bearing areas. Important to consider seeing as the strongest aluminums just barely hang with mild steel, and mild steel is not necessarily sufficiently strong to use just anywhere in a gun action.
It also costs wildly more than steel for such a purpose, has terrible-awful corrosion resistance for outdoor structural stuff like that (and has terrible corrosion-fatigue characteristics; stress actually makes the stuff corrode!), and the non-infinite service is just a bad idea all around for a project that you just know is gonna be both designed and maintained on the cheap (the service life will be designed to be lower than the realistic maintenance it will receive). The stuff's plenty flexible, that's why they use it on airplane wings & fuselages which flex up and down a ton, and inflate like a balloon at altitude; you just have to take into account that doing so starts burning through that service life, and mandate a diligent inspection/maintenance schedule to catch the cracks before they start affecting net strength*. That expectation just isn't realistic for a bridge (except for the rare exception like the Golden Gate which requires so much inspection/service that no sane person would ever duplicate it). Finding fasteners that won't corrode aluminum without being dipped in poisonous heavy metals is hard, also
I've heard some of the early Russian MIG jet fighters had steel skins, much to the humor of our analysts, who of course thought it was the crudest thing they'd ever seen (I'm sure the Russian engineers laughed just as hard at the scandalous decadence of our titanium-skinned Blackbird, and not without reason). Of course, the skins were approximately 1/3 the thickness of ours so about the same strength & weight
. They could only do this on the small planes, though, because the steel was not flexible enough; luckily jet fighters are darn near rigid bricks, compared to a spindly cargo plane or jet liner.TCB
*every commercial plane you will ever fly on has a number of active cracks propagating on it; many of them known to the airline, and simply being tracked in advance of a planned overhaul. Otherwise, they will be repaired with a mere stop-drill or ugly patch.
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I think that probably is true, but I also believe it's a pretty negligible effect. I suppose one could calculate it though based on the cross-sectional area of the casewall at the point where they typically thin is multiplied by the ultimate tensile yield stress for cartridge brass. In theory that would be all the tensile aid you'd ever muster from a case helping to resist bolt thrust.
You are using logic and reasoning whereas what Bart Bobbitt is using is an argument derived from authority. It all comes from an old, old Army coverup. The Army made 1,000,000 defective M1903's in their Arsenals. We know that in the forge shops the Army had not installed temperature gages so temperatures were judged by human eyeballs. Human eyeballs were not precise enough and anything that went through the forge shop risked being overheated. That is, burnt to a brittle condition. Per Hatcher's Notebook, at least 33% of these early receivers were seriously structurally compromised. At the same time, cupro nickel bullets fouled something horrible. The cure for the jacket fouling was dipping the bullets in grease. I have done this, and it really, really works. But, when ever a M1903 blew up, with Army ammunition, in an Army rifle, instead of acknowledging that they built crappy rifles and crappy ammunition, the Army claimed that greased bullets dangerously raise pressures. In 1920, Major Townsend Whelen thought he found the cure for cupro nickel jacket fouling by tin plating the bullets. In the Army press of the time, the hosanna's put out on this tin can ammunition would have made world peace and curing world hunger small potatoes compared to his discovery. Anyway Major Whelen oversold his tin can bullets and convinced Army brass he had found the solution to jacket fouling. Given that now grease was un needed, a Council of Colonels told Major Whelen to prove the evils of grease, and get the grease out of the shooting game. Major Whelen did so, created a bogus study that is the foundational document for this theory. According to his study greased bullets dangerously raised pressures, giving the bosses the excuse they needed to get grease off the firing line.
It is interesting to know, that the Italians, Russians, Austrians, and Swiss all issued ammunition with greased bullets. I have only been able to verify that the US Ordnance Department knew of the Swiss greased bullets. The Swiss had been applying a grease layer on their ammunition from the 1880's up to the 1980's.
The Army knew this, but in the Arms and Man, claimed that the only thing the Swiss did with these bullets was shoot holes in cheese!. Apparently the Swiss were unaware of the high pressures created by these rounds, whereas the clever Army Ordnance Department did. (What this does show is the arrogance and incompetence of the US Army Ordnance Department)
Key to this coverup was the idea that lubrication increased "bolt thrust". Maybe you can see the logic here, if you are issuing structurally defective rifles to your troops, being able to claim that the rifles are blowing up because of "increased bolt thrust" , that is shooter negligence, the Army was able to shift blame from its self onto the shooters. The actual fault was a failure of Army Leadership to acknowledge that they had a problem within their Arsenals, and even after they knew, they refused to admit the problems they created to themselves, or the public. The Army Ordnance Department was in big, big, denial. From my research, the Army never admitted in public that they created structurally deficient rifles. After an Army study in 1927, eleven years after they installed temperature gages in their Arsenals, the Army did a study and a board recommended scrapping all 1,000,000 rifles. The Army did no such thing, but the word got out, it was garbled, something about single heat treatment versus double heat treatment, but the Army knew it had defective rifles, but in public, was putting out rubbish like this:
Since many people are totally oblivious to the idea that structures are designed to carry a load, and don't have the slightly idea what a load limit is,
if an authority figure tells them that grease or oil, rubbed on the outside of a cartridge case will dangerously increase chamber pressure and dangerously increase bolt thrust, most people will believe it. Bart Bobbitt is obviously one of these types.
Stay within SAAMI pressures and you will have no problems, greased, oiled, or dry. Stay within SAAMI pressures and the structural lifetime will be within the design limits, be the firearm made of brass, aluminum, or steel. All modern firearms are designed to a load. Exceed that load, exceed those pressures which translates into load, and the lifetime of the firearm will be decreased.
This whole episode is an interesting example of how irrational humans are and how susceptible we are to group think. You would think rationale intelligent men would question these theories after loading and firing a Pedersen rifle:
After all, the Pedersen rifle required lubricated ammunition to function. But, people will shape and mold themselves to the group think. If the group think believes in fallacious theories, people will accept contradictory evidence as true in order to be accepted by the group. So, important people at the time accepted the contradictory idea that grease and oil dangerously increase bolt thrust but at the same time believed that lubricated cartridges are necessary for the Pedersen rifle to function. Well one of these ideas has to be false, but to many, both of these are true. This really shows the irrationally of the human mind, and that many of the things we believe, we have never challenged their validity. Never tried to test them to see if they are true.
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justin22885
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but herein lies the problem with 40S&W vs 9mm, 40S&W carries with it a bigger load being crammed into frames that were generally only designed to handle the lighter load of that 9mm.. modern gun manufacturers have been exceeding loads, decreasing the life of a pistol all to save a few extra dollars having to come up with a stronger firearm to handle higher thrust cartridges
and your point about believing anything people of authority say is true, because every single firearms manufacturer out there is cutting corners and telling you its for your own good so people buy it.. aluminum is clearly weaker, wont last nearly as long so they sell you on the "b..b..but it weighs less" as the average shooter doesnt have the intelligence to understand anything else discussed
if your pistol is short lived or taking damage using factor .40S&W ammo, then its clearly the fault of manufacturers cutting corners by making 40s on frames only designed to handle 9s or using weaker materials that are cheaper to machine (like aluminum)
and your point about believing anything people of authority say is true, because every single firearms manufacturer out there is cutting corners and telling you its for your own good so people buy it.. aluminum is clearly weaker, wont last nearly as long so they sell you on the "b..b..but it weighs less" as the average shooter doesnt have the intelligence to understand anything else discussed
if your pistol is short lived or taking damage using factor .40S&W ammo, then its clearly the fault of manufacturers cutting corners by making 40s on frames only designed to handle 9s or using weaker materials that are cheaper to machine (like aluminum)
Oh god, not the war on aluminum again:banghead:
Regarding .40 shortening the life of a gun vs 9mm, that will be true whether the gun was designed for 9mm or .40 originally. The 9mm should always last longer if the design is otherwise the same. It's just less abusive. I guess the frame of reference is how much life you consider enough. Clearly, you are very fixated on design life but that does not mean everyone else is, nor that it drives every design decision by everyone else. Not everyone plans to shoot 1,000,000 of extra-high-pressure 9x25/5.56 +p+p+ Steyr-wildcat nukes through their gun in their lifetime. Lots of folks only shoot a few hundred factory rounds a year of a plain-Jane caliber and are quite happy with the tradeoff of weight and corrosion resistance vs longevity.
Regarding .40 shortening the life of a gun vs 9mm, that will be true whether the gun was designed for 9mm or .40 originally. The 9mm should always last longer if the design is otherwise the same. It's just less abusive. I guess the frame of reference is how much life you consider enough. Clearly, you are very fixated on design life but that does not mean everyone else is, nor that it drives every design decision by everyone else. Not everyone plans to shoot 1,000,000 of extra-high-pressure 9x25/5.56 +p+p+ Steyr-wildcat nukes through their gun in their lifetime. Lots of folks only shoot a few hundred factory rounds a year of a plain-Jane caliber and are quite happy with the tradeoff of weight and corrosion resistance vs longevity.
Onward Allusion
Member
Maybe for pocket pistols and other light duty guns but a full size duty weapon will go 30K & up without issues.
I think the terms "overbore" and "barrel burners" sum up this topic, or at least contribute to it.
There are reasonable ratios involved in PSI, powder, size of bullet and barrel. Go above that, and things wear out faster. It's all metallurgy, chemistry and physics. You're not going to get away from the science.
There are reasonable ratios involved in PSI, powder, size of bullet and barrel. Go above that, and things wear out faster. It's all metallurgy, chemistry and physics. You're not going to get away from the science.
Destructo6
Member
Nope, under 10k.
Feed your favorite gun 10k worth of Federal Classic 155grn JHP (blue and silver box) and get back to me.
I've done it.
Walt Sherrill
Member
Justin22885 said:
Perhaps. But slide velocity seems to be their main concern -- which is why many of the gun makers go to heavier slides rather than just heavier recoil springs. Both approaches will manage the greater velocity, but a heavier, beefier slide, also offers them a chance to reinforce the slide in critical places. With some guns, they also beef up the locking block or other interface areas in the frame. I know where talking about steel- or alloy-framed guns, but Glock uses the same recoil spring in their model 19 (9mm), model 23 (.40), model 32 (.357 SIG)and model 38 (.45 GAP). There's quite a spread of pressures and calibers in those four guns... The recoil springs are the same, but the slides are noticeably different (except maybe in the 23/32 -- I haven't had a 32, but have used a .357 conversion barrel in my Model 23.)
Justin22885 said:
You offer two choices when there might be three: with a heavier recoil spring installed, the slide doesn't have to travel back at a higher velocity -- but manually racking the slide will likely become more difficult.
I'm not sure whether pressure against the breech (or the other end of the slide) is a key concern for gun designers, or whether it's slide velocity and its effect on other parts of weapon. It may be these two things are same issue observed from different points of view. I'll leave that to folks who understand these thing better than I do.
On the other hand, talking about a gun frame that last longer because it is made of steel is arguably an empty discussion -- as darned few of us will ever shoot a weapon enough to wear it out, unless we buy a very poorly designed gun made from poorer-quality materials.
And as many of us buy more guns, the time available to shoot just gets spread over more and more guns.
Our longevity is probably a bigger concern than the gun's longevity.
MachIVshooter
Member
Those terms simply don't apply to straight walled handgun cartridges, though.
With Semi-automatic handguns using any kind of recoil or blowback operation, slide velocity is the killer. I don't ever recall hearing of the barrel lug(s) which engage the slide on a recoil operated gun shearing (a bolt thrust issue), but cracked slides and frames, or contact points being battered from the impact of the slide, is an issue. Also snapping one or the other end of reciprocating beveled surfaces/camming lugs/locking blocks as a result of things moving too fast.
Conversely, the failure in weapons utilizing fixed barrels with positive locking mechanisms (be it bolt, gas, lever, pump or other action) typically see failure of the locking lugs.
Perhaps. But slide velocity seems to be their main concern -- which is why many of the gun makers go to heavier slides rather than just heavier recoil springs. Both approaches will manage the greater velocity, but a heavier, beefier slide, also offers them a chance to reinforce the slide in critical places. With some guns, they also beef up the locking block or other interface areas in the frame. I know where talking about steel- or alloy-framed guns, but Glock uses the same recoil spring in their model 19 (9mm), model 23 (.40), model 32 (.357 SIG)and model 38 (.45 GAP). There's quite a spread of pressures and calibers in those four guns... The recoil springs are the same, but the slides are noticeably different (except maybe in the 23/32 -- I haven't had a 32, but have used a .357 conversion barrel in my Model 23.)
You offer two choices when there might be three: with a heavier recoil spring installed, the slide doesn't have to travel back at a higher velocity -- but manually racking the slide will likely become more difficult.
I'm not sure whether pressure against the breech (or the other end of the slide) is a key concern for gun designers, or whether it's slide velocity and its effect on other parts of weapon. It may be these two things are same issue observed from different points of view. I'll leave that to folks who understand these thing better than I do.
On the other hand, talking about a gun frame that last longer because it is made of steel is arguably an empty discussion -- as darned few of us will ever shoot a weapon enough to wear it out, unless we buy a very poorly designed gun made from poorer-quality materials.
And as many of us buy more guns, the time available to shoot just gets spread over more and more guns.
Recoil springs were the same on the gen 3, but that all changed with the gen4. They are now different.
What gun, what other rounds, what happened
atblis
Member
HK P2000. Sounds like it's more a material defect or design issue for that particular pistol.
Surely somebody has some rental range gun experiences with the Glock 22 versus the 17.
Surely somebody has some rental range gun experiences with the Glock 22 versus the 17.
Zerodefect
member
You just have to change the recoil springs more frequently with the .357 and .40. Otherwise the frames will fail sooner than 9mm/.45.
Not a big deal, send it to Glock and they'll get you a new frame for less than the cost of a small amount of ammo.
I wouldn't recommend using this wear as an excuse to prefer a certain type of defensive pistol. Performance and reliability would be better boxes to check.
Not a big deal, send it to Glock and they'll get you a new frame for less than the cost of a small amount of ammo.
I wouldn't recommend using this wear as an excuse to prefer a certain type of defensive pistol. Performance and reliability would be better boxes to check.
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