Slide/Frame Integrity


Cactus Jack Arizona
May 29, 2010, 08:17 AM
Down at my local range, there is an opinion regarding the wear and tear caused by the friction of the slide movement. Popular opinion is that a steel frame can withstand the most "abuse" without losing integrity of strength, form, and function as opposed to the aluminum or polymer frames.

So, I must ask, what's your opinion on the subject? Will aluminum and polymer frames weather the punishment of constant use? Of course, we expect them too when they're new, but what about after 5, 10, 20+ years of constant use?

*Let's clarify the term "constant use":
9mm pistol (one of each type of full-size frame: Steel, Aluminum, Polymer)
115gr. WWB FMJ
300 rounds shot each week in various numbers of range visits.

If you enjoyed reading about "Slide/Frame Integrity" here in archive, you'll LOVE our community. Come join today for the full version!
The Lone Haranguer
May 29, 2010, 08:23 AM
Heat treated steel running against the relatively softer aluminum frame will eventually wear down the frame rails. Keep the gun lubricated, though - here is a use for grease instead of oil - and the difference is minimal. Alloy-framed guns can have a very long service life. This is a moot issue with polymer frames, as with very few exceptions the slide actually runs on steel rails and there is little or no actual contact between the slide and frame. Many such guns actually have a gap between them.

May 29, 2010, 11:21 AM
I have a few handguns with the aluminum frame, steel slide setup. What would be a BALLPARK round count on them as far as their wear out? I have:

CZ75 SP-01

Springfield Armory EMP

I have polymer framed pistols that I really don't worry about, myself. Now, I DO have a steel frame .380, and if the steel is a more softer variety, it could beat itself out of shape too, . . . so I've heard [such as some of the cheaper Star brand pistols]. My steel on steel is an F.I. Industries Model D. It's a relatively rare pistol, so I feel like I should keep it in the safe and just get a small Ruger LCP.

May 29, 2010, 12:13 PM
I've seen alloy frame SIG P226's and P220's (range rentals and some friends' competition guns) with at least 25-30 thousand rounds through them (a couple of the range rentals I was told with over 50 thousand and I'd easily believe that) and they still were solid and sound. I would think any well built alloy frame with a steel slide should be good for a bare minimum of 50K rounds.

Of course, it would depend a lot on how they were used (or abused, as the case may be) and cared for. An all steel gun may last longer then an alloy framed one, but the difference may only show up at round counts that the vast majority of owners will never achieve in an entire lifetime.

Cactus Jack Arizona
May 30, 2010, 12:41 AM
Actually Doc, I am married and that's why I ask such questions. I haven't the money or the time to actually test these things out on my own. :D

May 30, 2010, 01:06 AM
posted by 2075 RAMI
*Let's clarify the term "constant use":
9mm pistol (one of each type of full-size frame: Steel, Aluminum, Polymer)
115gr. WWB FMJ
300 rounds shot each week in various numbers of range visits.

clarification is a good thing, but you're only talking about 15k rounds a year...i've always considered that "hard use" started at 25k/year. i've shot a Sig 226 that was still more than accurate enough after well over 65k rounds and have handle ones that had over 100k through them, rattled like a tin can and still shot well enough for defensive work.

i believe the Sig family has an expected life of about 100k rounds with regular spring changes and proper lube

the ultimate answer to your original question is that the steel framed gun should last longer, but most folks will never put that many rounds through it...if for no other reason than the cost of the ammo

Full Metal Jacket
May 30, 2010, 01:20 AM
strongest, in this order: polymer, steel, aluminum.

May 30, 2010, 10:04 AM
I find it interesting that the polymer would be considered the "strongest frame" over the steel.

May 30, 2010, 12:21 PM
posted by Orion8472
I find it interesting that the polymer would be considered the "strongest frame" over the steel.


it has the additional elasticity to spring back to shape...assuming it had the designed strength to handle the recoil to begin the strength of a katana coming from it's softer core

May 30, 2010, 12:30 PM
strongest, in this order: polymer, steel, aluminum.
FMJ stealing my posting glory again...

May 30, 2010, 01:49 PM
That's a true thought to consider. . . the give factor of the polymer where metal will just conform to the compression.

Full Metal Jacket
May 30, 2010, 02:01 PM
FMJ stealing my posting glory again...

lol :)

May 30, 2010, 03:29 PM
Wow, all those firearms companies must be really stupid for not making their slides and barrels out of polymer then.

As an engineering student, I would go Steel - Polymer - Aluminum.

The polymer frames have steel rails for the steel slide to ride on, the aluminum frames have sliding steel on aluminum, which is not that good. You get increased wear and possible corrosion when steel rubs on aluminum.


That is a data sheet for nylon 6 30% glass-fiber filled... approximately what these polymers are.

"Tensile Strength, Yield 95 - 195 MPa" Not exactly a specific number, no idea why they gave such a broad range. But most sites give non-glass filed nylon a yield strength of around 50 MPa.

Compare to:

Stainless Steel, AISI 302 ------- 502 Mpa
Steel, Structural ASTM-A36 -------- 250 MPa
Steel, High Strength Alloy ASTM A-514 ---------690 MPa

Yield strength is the point at which you go past it, you plastically deform the material.

Let me pull out my "Materials Science and Engineering: An Introduction 7th Edition" by William D Callister and see what it says about steel strength.

From Appendix 11:
yield strength of oil-quenched and tempered 4140 steel is 1570 MPa

The highest value i find for aluminum is:
aluminum alloy 7075 heat treated and aged (T6 temper) is 505 MPa.

And i see in the book they have "nylon 6.6 dry, as molded" and the yield strength is 82.8 MPa. That is without glass fibers or other chemicals.

I also see the appendix has a "Strength^a" description which is associated with fracture toughness in the chart.
Steel alloy 4140 tempered at 370C --------- 1375-1585 MPa
Stainless alloy 17-7PH precipitation hardened at 510C -------- 1310 MPa
aluminum alloy 7075-T651 --------------- 495 MPa
titanium alloy Ti-6Al-4V ----------------- 910 MPa
nylon 6.6 ---------------------- 44.8-58.6 MPa
Polycarbonate (PC) --------------- 62.1 MPa

I'd go with carbon steel. Just because something can flex and spring back does not mean it is better than something that wont flex, yet will take the same amount of force as if it was nothing. There is a big difference between non heat treated steel and heat treated steel. The heat treatment will make all the difference in the world too. In my engineering materials labs we have done heat treatment experiments. Heating a metal and then quenching it in water will give it a good hardness, yet absolutely brittle. When we tested it, the machine didn't even register a force when it broke. Then we tested the metal when quenched in oil.... it took a great amount of force to snap it. A company's heat treatment will either make victory or defeat. And most companies today do have the proper heat treatment.

May 30, 2010, 03:35 PM
With out knowing the exact properties, processes, and specifications, no one will ever know.

Such as, the assumption of soft aluminum could be over come by using a harder grade... then countered by tempering of steel.... then hard coatings applied to said materials. Polymers come in a milion and one formulations each with different properties with their rails and slides ultimately made of metal.

Impossible to know.

This will end up being polymer people vs metal people with no answer.

May 30, 2010, 04:45 PM
While engineers can make modifications to designs and select specific materials to better meet the demands of expected operating conditions and situations over the course of an expected service life, I'd think that all-steel guns would still have an ultimate advantage over those with alloy frames. Whether most owners would ever shoot the guns enough to realize that advantage is open to debate.

Proper use of alloys and careful attention to maintenance practices (lubrication & spring replacement) can help prolong the service life of alloy-framed pistols, too.

I remember back in the late 80's when there was some testing done by the FBI to determine whether alloy-framed pistols would be suitable for extended service in LE roles. (You have to remember that back then the typical service life specification for a military pistol was 5,000 rounds.)

Once it was observed that some of the alloy-framed pistols of that time period (including some 459's & 226's) exhibited cracked frames within 10,000 rounds, some of the firearms manufacturers responded by making changes to their alloy-framed pistols so they would provide longer service for LE use. We've all benefited from being able to buy improved alloy-frame pistols with much longer expected service lives since that time.

Steel frames were found to last significantly longer, though. No real surprise.

The use of different plastic formulations for pistol frames resulted in the use of steel frame rail inserts and reduced the contact surfaces between the frames and slides. While the steel inserts could provide a good service life, some changes in the shape, length and manufacture of the steel frame rail inserts continued to occur to address potential user issues. Also, even though the frame & slide rails were steel, manufacturers looked to find ways to better disperse and manage the recoil forces being experienced by the rest of the plastic frames (locking blocks, locking block pins, steel frame inserts at critical areas of stress, etc). Slide mass and recoil spring calibration became a fine dance. ;)

Plastic frames can withstand certain forces very well and provide for useful service lives ... although I'd be less inclined to use one to hammer a wanted poster to a wall or post. :neener: Joking aside, they can chip or perhaps suffer cracks more easily than metal under some conditions. The selection of plastic is carefully made taking into consideration its inherent advantages & disadvantages for different uses in firearms.

Nowadays we're seeing designs which allow for the replacement of steel frame rail inserts by way of replacing modular components. This allows for frame rail replacement, if needed, without having to replace the frame.

One of the newer designs, the M&P pistol being produced by S&W, even has stainless steel inserts molded into the frame to form a sub-chassis. The sear housing block and locking block (which contain the frame rails) are mounted within the frame and secured by steel coil pins which pretty much makes for a solid steel 'box' to absorb and mitigate recoil forces.

The most I've ever fired through an alloy-framed pistol was in a 9mm, one of the very production 3rd gen 6906's. I estimated I fired upwards of 45,000 rounds through that particular gun. It involved replacement of springs and some other parts over the course of that time, of course, and the frame was starting to look a bit worn toward the end, but it was still functional. I remember talking to some at the factory about it one time, and the fellow just chuckled and said that back when that gun had been produced they had never thought someone would ever try to shoot that many rounds through one. he also said that if I eventually managed to wear it out, that as an agency-owned LE weapon they'd replace it with something else (S&W offered their lifetime warranty to LE customers before it was offered to the general public). No need, as we were going to be replacing all of the older 3rd gen weapons with new ones, anyway. ;)

There's another retired gentleman who posts on some of the firearm forums (can't remember if he visits this one, though) who has related how a friend of his, a former firearms instructor for an agency who used S&W alloy 9mm's for about 30 years, logged over 50,000 rounds of 115gr +P+ loads through an alloy-framed S&W. He reportedly kept the gun upon his retirement and was continuing to shoot it. I'm going to make a guess that he inspected and maintained the gun as recommended by the manufacturer.

I've fired several thousand rounds through a number of other alloy S&W's. Just nothing approaching the amount I fired through that one 6906. I examined a 3913TSW which experienced a frame crack in the front of the dustcover, which I was told by someone at the company was considered odd (and not in what they considered a critical location), and they cheerfully replaced the gun with another one for the owner. The owner estimated he'd fired between 12-15K rounds through the gun before I noticed the small crack (he thought it was a scratch). He's probably exceeded that amount in the replacement gun by now (he shoots a LOT) and it's been fine so far when I've periodically examined it. I've also given him a goodly supply of recoil springs and made sure he replaces them periodically, too. ;)

This same fellow has fired more than 50,000 rounds through a pair of SW99's, too, one each chambered in 9mm and .40 S&W. Aside from an ammunition-related problem in the 9mm early in its life (a case head failure/blowout which damaged the frame and was replaced by S&W under warranty), and a broken ejector in the .40 at just over 50,000 rounds (which required a new sear housing block because the ejector is molded into the housing block, and which was sent to me at no charge as a warranty replacement part even with such a high round count) ... the guns have run well and long with only periodic spring replacements of various sorts.

I expect his SW99's to be running for years to come. I remember being told of a SW99 used in the factory's training academy which had been intentionally run without cleaning and lubrication, and no replacement parts, in excess of 75,000 rounds (last I heard). I just keep the fellow in replacement springs and make sure he cleans and lubricates the guns.

Oh yeah, the same guy has an all-stainless Colt OM .45 which was used to shoot over 20K rounds after it had been refined & tuned a bit. During that time he cracked a barrel bushing at over 10K rounds. He retired that little steel .45 to start carrying some alloy .45's & 9mm's as well as the plastic 9mm's & .40's.

I've got more than 10,000 rounds each through some small plastic guns (G26/27 & a SW99 9c) with only some spring and assorted small parts replacement. I expect them to run for some time with normal preventive maintenance practices.

Now, after all of my babbling, my point is that while all-steel guns can probably be expected to outlast most folks who own them, even the better quality alloy & plastic-framed guns have received some design and materials improvements over the years and are probably going to outlast most folks who buy and use them.

Of course, when you consider that the so called 'average' handgun owner is still considered likely to fire less than a couple boxes of ammunition through their handguns over the course of owning them, that's probably not a hard trick to manage. :neener:

Hey, just my random thoughts. As a firearms instructor and armorer of some small experience I've had a chance to experience, observe, be told about and read about things related to this subject from time to time.

I may still have a personal reference for an all-steel pistol, but I've long since accepted that alloy & plastic guns can be run hard and long ... as long as they receive the recommended maintenance. I certainly own and carry enough of them nowadays.

Enjoyable topic and discussion.

Remember when folks still hadn't accepted the "Coltalloy®" frame on the Commander? I think I still have a gun magazine buried somewhere with an article of an endurance test done by one of the popular writers of the 70's where a 'lightweight' Commander was successfully used to shoot 5,000 rounds. I bought that magazine because I listened to some of the nonsense about fears using aluminum Commanders for a lot of shooting. I eventually succumbed to gunshop myths of that time and traded it off for a steel "Combat" Commander. I plead youth and inexperience back then ...

May 30, 2010, 05:10 PM
My L/W Commander is still rocking on. Will it break someday? Sooner or later all mechanical things break, but it will probably be after I am gone.

Will my XD melt/crack/split someday? Probably not in my lifetime.

I certainly don't lay awake worrying about either gun, nor all the others I have. :)

May 31, 2010, 04:11 PM

Just don't leave your polymer framed gun out in the sun too long or too many times.

And, any weakness in polymer frames will stand out in cold weather.. The colder it gets, the less it will flex until, no flex.. (brittle)

Other than that, I'm keeping my Px4 40..



If you enjoyed reading about "Slide/Frame Integrity" here in archive, you'll LOVE our community. Come join today for the full version!