What is the of +P ammunition on guns not rated for its use?

[Stacts]

I'm new to reloading and newer to this community. I have only reloaded for .380 and .38 special so far.

I'm curious about the effect that +P ammunition would have on a revolver not designed for its use. I can understand the effect +P ammo would have on a semi-auto pistol: Increasing the slide velocity and battering the moving parts into each other faster than the design intended.

I'm having a harder time understanding what happens to a revolver when +P ammo is used. I'm not talking about double-charged ammunition or similar gross overpressure situations.

I've read speculations about frames stretching but little in the way of first-hand information.

I guess the reason I'm curious is that some years ago, my friend and I each had a .38 special. His was all steel with thicker cylinder walls than mine. It was a Taurus and NOT rated +P. Mine was a Ruger and had (has... I still have it) +P printed on the side of the barrel. I can't figure out what +P would have done to my friend's revolver over time.

[Thumbcocker]

Might not blow it up but will definitely wear it out faster.

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[cwtebay]

I think that describing your revolver of choice might be a good place to begin.
+P = + Problems in ANY gun not designed to handle that sort of pressure.


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[Stacts]

Might not blow it up but will definitely wear it out faster.

I've seen people say that. What wears out? Locking lug? Firing pin/Hammer? Forcing cone? Why and how?

As far as my gun, it's a Ruger LCR. https://ruger.com/products/lcrx/specSheets/5431.html

As I said, I'm curious and trying to learn.

[Frosty Boolit]

Someone correct me if I'm wrong but it was advances in heat treating technology that allowed the +p in revolvers. If this is true than I would say that any steel component that is exposed to chamber pressure would be the parts that would take the greater wear in a non +p rated revolver.

[Stacts]

So the cylinder would stretch? Would it be measurable before catastrophic failure?

[smkummer]

So in the late 70’s to mid 90’s, Colt used to put the recommendation in its owners brochure of the D frame revolvers (detective special, agent, cobra, police positive special and diamondback) that after 1k rounds of plus P in its alloy frame guns and 3K rounds on its steel frame guns to have either the factory or a service center check the gun out for wear and proper function. One of my carry guns is an alloy agent stuffed with plus P. I practice with standard ammo and have fired a few cylinders of plus P.

Your not going to stretch a steel cylinder. But it’s possible that long term use of plus P could loosen the alloy frame. Possible.

[Stacts]

Loosen what in the frame? and how?

Is it through shock? Vibrations? I'm really curious for details.

[wv109323]

Metals of yesteryear were not as strong as todays alloys. Also smaller pistols are made small for reduced weight. There is not as much "meat" to take the forces of high pressure loads. Two areas of concern are the breechface that holds the cartridge from moving rearward when fired. Next are the hand ,hole in the frame where the hand is lifted through, and the cylinder notches. These areas are subject to stress and wear when a cartridge is fired. After abuse they affect the lock-up and the pistol will be out of "time". The cylinder notches are wider, the end of the hand gets tapered and the slot in the frame gets wider thus allowing more rotational wear that allows shaving of lead.

[rintinglen]

The specific cause of the damage is the increased force of the bullet slamming into the forcing cone, driving the barrel forward and drawing the topstrap along with it while the cartridge case is driven to the rear.

The problems that I have seen have been frame stretch, specifically top strap stretch, and excessive fore and aft play on the cylinder, resulting in an enlarged barrel cylinder gap and occasional light hammer strikes due to the cylinder not being held as firmly to the rear. The repair involves inserting washers to reduce the cylinder end-play and removing the barrel, turning the shoulder to allow it to be screwed in one more turn and the forcing cone cut to proper length to correct the barrel-cylinder gap.

Oh and it also involves money, about three Benjamins worth, maybe more, depending on the severity of the damage.

[Outpost75]

I have LOTS of experience with this, having worn out or destroyed a dozen .38 revolvers shooting +P and +P+ in guns not suited for them.

Failure mechanism is frame stretching in which gun develops cylinder end shake. Once end shake exceeds about 0.002" with each round cylinder setback pounds frame to increase head clearance. After about 500 rounds end shake will reach 0.002". This can be corrected by stretching S&W crane or swaging cylinder bushing on Colt, but will increase barrel-cylinder gap. On S&W crane can be stretched only twice before gun originally built at Mean Assembly Tolerance of 0.005" pass/0.006" hold barrel cylinder gap will increase to barrel-cylder gap of max. 0.008" pass/0.009" hold. Once gap exceeds .0.009" it is necessary to either set barrel back (gunsmith fix) or refit "long" +0.005" cylinder (factory fix). Velocity loss in .38 Special.is about 10 fps for each 0.001" increase in cylinder gap above Mean Assembly Tolerance, 20 fps for .38 Spl. +P and 30 fps in .357.

If not corrected cylinder to recoil shield head clearance will increase above 0.065" max. and the combined effect of loose head space and excessive and shake will cause light strikes and misfires.

Driven protrusion of striker point should be in range of0.028-0.032" with centrality of striker being off no more than 1/2 the diameter of the striker point. Striker indent measured on annealed copper cylinder must not be less than 0.010" for .38 Special or 0.011" in .357 measured in DA with muzzle horizontal.

[dverna]

I love this forum. I learned a lot on this thread.

[Geezer in NH]

I would think frame Strech and top strap failure along with cylinder failure. My nephew blew a cylinder on a SW36 3 inch with +p loads.

Go for it if you want to shoot +p's but you have been warned it may not turn out well.

[Bazoo]

Very informative info. Thanks all, and to outpost specifically.

[hawkenhunter50]

Handloader magazine, I think it is the latest issue has an article on 45 Colt +P. Might be worth a read as the author discusses different makes of revolvers and what makes them suitable or not for the different pressure levels of ammo. Not quite as detailed as some of the info posted here but still worth a read.

[Winger Ed.]

I try not to overthink this sort of thing.

Compare shooting +P in a gun not designed for them to driving the family car at 125mph.
It'll do it, for awhile. But it'll last a lot longer if you keep it under 80 most of the time.

[FergusonTO35]

If I'm not mistaken, Taurus says that all their .38 Special firearms are +P rated except the magnesium frame versions.

[Scrounge]

I'm new to reloading and newer to this community. I have only reloaded for .380 and .38 special so far.

I'm curious about the effect that +P ammunition would have on a revolver not designed for its use. I can understand the effect +P ammo would have on a semi-auto pistol: Increasing the slide velocity and battering the moving parts into each other faster than the design intended.

I'm having a harder time understanding what happens to a revolver when +P ammo is used. I'm not talking about double-charged ammunition or similar gross overpressure situations.

I've read speculations about frames stretching but little in the way of first-hand information.

I guess the reason I'm curious is that some years ago, my friend and I each had a .38 special. His was all steel with thicker cylinder walls than mine. It was a Taurus and NOT rated +P. Mine was a Ruger and had (has... I still have it) +P printed on the side of the barrel. I can't figure out what +P would have done to my friend's revolver over time.

https://www.nde-ed.org/Physics/Materials/Structure/deformation.xhtml Ever bent a piece of metal? Ever bent a piece of metal until it breaks? If you don't bend it too far, it will regain its original shape. If you keep bending it, you'll get stress fractures, and it will eventually break. With a gun, it depends on how much you shoot it. Shoot a hundred rounds a week at normal pressures it might last a lifetime or more. Shoot a thousand rounds a week at normal pressure it might still be good for a life time, but maybe not. Shoot a hundred rounds a week at +P pressures, on a gun not designed for them, and it might only last 10 years. The cylinder is going to stretch a bit. A microscopic bit, truly, but still it stretches. The more you shoot it that way, the shorter its life will be. If you're only shooting +P ammo in defensive situations, or the occasional short practice with +P ammo, it's not going to get as much wear as if you shoot a hundred +P rounds a week.

I have a Stevens Favorite single-shot rifle that my dad bought broken in late 40's or early 50's. It's an 1889 model, from the internal parts. One of his repairs was to put a blob of brass braze on the shank of the screw that held the lever in, and then file it to replace the broken head of the screw. All my younger brothers and sisters learned to shoot with that rifle, which was designed when .22LR was a black powder load. Modern smokeless powder loads are more powerful and higher pressure than the original load. Eventually, that rifle started leaking around the shell, and we retired it as a wall hanger. We thought the barrel & chamber was shot out. I really wanted to shoot it again, and was bored to tears during the Covid-19 lockdown, so I bought replacement screws for the ones he'd repaired or replaced. Turned out that brazed head had stretched out, and the breach wasn't locking up. Shoots as well as it did when I was kid now. Might not have done that will a steel screw, though if we'd keep shooting it, it might be truly worn out by now.

Any part of the revolver that gets movement caused by the powder burning in the cylinder is going to get a little wear. The frame, the center pin, the bore of each cylinder, the extractor, and all those related parts that touch one another, including the face of the frame that the cylinder rests against. Also, you're going to get more flame cutting from the higher pressures, which will cause additional wear to the cylinder bore, forcing cone, and barrel, as well as the face of the frame around the cylinder gap.

Only you can determine if that is a deal killer for you or not. If you want to pass your firearms down to your kids as something other than a wall hanger, maybe you shouldn't be using +P ammo in a gun not designed for it. If you consider guns expendable it might be the right choice for you. Though, personally, I'd rather they last a lifetime or two, like my Favorite. I've been been buying sub-sonic .22LR for my Favorite, because I want my grandkids to learn to shoot with it, too, if I have any. ;)

HTH!

Bill

[Gtek]

Thank You Mr. Outpost75! (insert loud explosion noise here) Detailed description with dimensions and it just doesn't get any better than that, copy made and placed in S&W library.

[Bazoo]

I don’t recall where I read it now, but I read where they proofed revolvers and the barrel cylinder gap would open .003 from frame stretching, just from the firing of those proof loads.

[John in WYO]

Hi, Bill,

Great post on explaining +P effects on non +P firearms.

Auto-correct may have got to your statement.

“Turned out that brazed head had stretched out, and the breach wasn't locking up.”

Respectfully, it is the “breech” when referring to the end of a firearm wherein a cartridge is inserted into the chamber. I’m sure you already know that.

For our younger readers who missed English class and spelling or are stronger in math and science:

“Breach is a noun referring to (1) an opening or gap or (2) a violation or disruption, and a verb meaning (3) t o make a hole or gap in or to break through . Breech is only a noun. It refers to to (1) the lower rear portion of the human trunk, or (2) the part of a firearm behind the barrel.”

John

[Outpost75]

Thank You Mr. Outpost75! (insert loud explosion noise here) Detailed description with dimensions and it just doesn't get any better than that, copy made and placed in S&W library.

The 0.028-0.032 driven protrusion is for a frame-mounted firing pin. With firing pin mounted on hammer nose striker tip protrudes at an angle so driven protrusion will be greater. Vector quantity and increased friction also reduces energy, so copper indent measurement is what determines acceptance.

[Handloader109]

If I'm not mistaken, Taurus says that all their .38 Special firearms are +P rated except the magnesium frame versions.ABSOLUTELY NOT. I've a polymer metal mix Taurus in 38 special and it states no +p ammo. Unless they are clearly marked +p, then they are not made for that ammo. Direct from the website and manual.

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[Gtek]

0.028"-0.032", revision updated. Thanks again!

[Scrounge]

Hi, Bill,

Great post on explaining +P effects on non +P firearms.

Auto-correct may have got to your statement.

“Turned out that brazed head had stretched out, and the breach wasn't locking up.”

Respectfully, it is the “breech” when referring to the end of a firearm wherein a cartridge is inserted into the chamber. I’m sure you already know that.

For our younger readers who missed English class and spelling or are stronger in math and science:

“Breach is a noun referring to (1) an opening or gap or (2) a violation or disruption, and a verb meaning (3) t o make a hole or gap in or to break through . Breech is only a noun. It refers to to (1) the lower rear portion of the human trunk, or (2) the part of a firearm behind the barrel.”

John

Breach is also the presentation of a baby feet first, instead of head first. They are complicated, and often result in death of both mother and child. And the plural of breech is a pair of pants. The number of meanings of a word in English is one of the reasons why it's one of the hardest to learn of all the non-tonal languages. And I get in a hurry and don't always proofread, which I should certainly know better by now. Let BedBugBilly know you caught me, it'll give him a chuckle!

Where ever possible I do not use Spellck because it meses things up. ;)

Bill

[Walks]

I heard that Steel frame S&W revolvers are ok with +P loads if they are Numbered, i.e. Model 10, Model 15. rather then older revolvers that are named, i.e. Military & Police, Combat masterpiece.

[Stacts]

Thank you for the replies.

The comment about the barrel being pushed out raises the next question: What is done to a revolver barrel to enable it to handle more pressure (such .357 mag. or even just a +P loading) without moving? Is it a material difference, a manufacture difference (as in tighter tolerances), or a design difference? (or any combination?)

What about the top strap? Do they simply thicken the metal or is some other strategy used?

What about firearms made before the employ of "+P" as a term? Is there a strategy to determine if such a revolver would be safe for +P ammunition?

Concerning cylinder stretch: Do the chambers in the cylinder widen or is the stretch length-wise?

Is there any way to detect the onset of these issues early?

Right now I'm just brimming with questions, so forgive me for their number.

[Scrounge]

Thank you for the replies.

The comment about the barrel being pushed out raises the next question: What is done to a revolver barrel to enable it to handle more pressure (such .357 mag. or even just a +P loading) without moving? Is it a material difference, a manufacture difference (as in tighter tolerances), or a design difference? (or any combination?)

What about the top strap? Do they simply thicken the metal or is some other strategy used?

What about firearms made before the employ of "+P" as a term? Is there a strategy to determine if such a revolver would be safe for +P ammunition?

Concerning cylinder stretch: Do the chambers in the cylinder widen or is the stretch length-wise?

Is there any way to detect the onset of these issues early?

Right now I'm just brimming with questions, so forgive me for their number.

Some of the original revolvers didn't have a backstrap. They couldn't be as strong as the ones with a backstrap just because the material of the day wasn't all that strong. As technology advances, you get alloys that are stronger because they figured out how to add them to the mix. There are also treatment for the metals that can make them tougher, harder, etc. Heat treatment is the blanket name. Used to be the books on metal working talked about hardening and tempering. Still do, but it's gotten a lot more complicated.

There are certain temperatures where the grain of the metal gets smaller, which is desirable, larger, which often isn't, and all of that depends on the particular mix of alloying elements in the particular alloy. Pick one alloy for certain properties, and another for different properties, use various heat-treatment techniques, and get the results you can. Use thicker, wider, heavier parts to make a gun tougher. They also do cryo treatments, now. Liquified gases, and that sort of thing.

Check out the Chiappa Rhino, for an example of bigger, thicker, heavier. But, while bigger, heavier guns can be easier to steady for a shot, they're more work to carry for a long time.

I would not use +P ammo in a gun that isn't rated for it unless you don't care if the gun lasts. If you're going to anyway, and you want to test it, you need high resolution measuring equipment. Even cheap imports are not really cheap, so you're going to be spending significant money buying the stuff to test the guns. Micrometers of several kinds, inside, outside, and depth, gauge blocks, a surface plate, surface gauge, optical comparators, etc. You'd also need to study metrology, so you learn what kinds of measuring and testing you'd need to do, and learn how to do it. Really, it's cheaper, easier, and faster, to just match the ammo to the gun. I've bought a bunch of the measuring equipment because I've been learning to become a machinist. Ain't there yet, but I've passed the class, got my certificate of completion this past weekend. For what I've spent on tooling, and I have not gotten all I want, I could probably have one nice higher end handgun. Not really high end, either.

Bill

[Stacts]

There are certain temperatures where the grain of the metal gets smaller, which is desirable, larger, which often isn't, and all of that depends on the particular mix of alloying elements in the particular alloy. Pick one alloy for certain properties, and another for different properties, use various heat-treatment techniques, and get the results you can. Use thicker, wider, heavier parts to make a gun tougher. They also do cryo treatments, now. Liquified gases, and that sort of thing.

Check out the Chiappa Rhino, for an example of bigger, thicker, heavier. But, while bigger, heavier guns can be easier to steady for a shot, they're more work to carry for a long time.

I would not use +P ammo in a gun that isn't rated for it unless you don't care if the gun lasts. If you're going to anyway, and you want to test it, you need high resolution measuring equipment. Even cheap imports are not really cheap, so you're going to be spending significant money buying the stuff to test the guns. Micrometers of several kinds, inside, outside, and depth, gauge blocks, a surface plate, surface gauge, optical comparators, etc. You'd also need to study metrology, so you learn what kinds of measuring and testing you'd need to do, and learn how to do it. Really, it's cheaper, easier, and faster, to just match the ammo to the gun. I've bought a bunch of the measuring equipment because I've been learning to become a machinist. Ain't there yet, but I've passed the class, got my certificate of completion this past weekend. For what I've spent on tooling, and I have not gotten all I want, I could probably have one nice higher end handgun. Not really high end, either.

Bill


So... the major difference is of material, and the second difference would be amount of material? Not necessarily a difference of design then?

[Outpost75]

The various engineering changes on S&W are the dashed numbers after the model number stamped in the yoke cut. After the Model 10-5 heat treatment was changed and other changes made to enhance durability with +P. Older S&W revolvers are no longer serviced by the factory, because parts are no longer available.

[Stacts]

... and other changes made to enhance durability...

Such as?

I'm really trying to learn more of the details.

[Groo]

Groo here
Much depends on the gun.
S&W says that all model marked STEEL guns are ok for +p...[ m-10 etc]
Note this may be because the STEEL guns [including steel J frames] were proofed for 38-44 high speed ammo.[between 38 and 357] and modern +p is of equal or lesser pressure.

[Outpost75]

Groo here
Much depends on the gun.
S&W says that all model marked STEEL guns are ok for +p...[ m-10 etc]
Note this may be because the STEEL guns [including steel J frames] were proofed for 38-44 high speed ammo.[between 38 and 357] and modern +p is of equal or lesser pressure.

If you believe that I have a good deal for you on a bridge in Brooklyn. S&W corporate honesty is on a parity with VW.

The pre-1980 J and K frames are plain carbon steel similar to 1050 quenched and tempered and most will not even register on the Rockwell C scale. About 80-90 Rb is common. The Model 19, 10-6 and later and Model 13 are typically Rc 20-24 in the frame and Rc 30 in the cylinder, as were the .38-44 Heavy Duty and the other N-frames. A Model 19 .357 requires factory rebuild after about 1000-1500 rounds of .357 and a later Model 10-8, model 64 or 66 will not pass a 5000 round endurance test with .38 Special 110-grain Treasury loads. Later L frames did better and passed, but had the primer cup flow and cylinder lockup problem. Test reports of S&W 65 and Rugers from Customs and Border Patrol are public domain and readily obtained. If you would PM me with an email address which will accept 15MB in .pdf files I can send copies you.

Also read Mike Wood's articles in Police One and on the Revolver Guy blog about barrel cracking issues in .357.
Here are some pics of S&W Scandium, Ti and MIM part failures for you:

300834300835300836300837300838

[Stacts]

I'm interested in any information you can share.

Their .357s can't last more than 1500 rounds without work? I don't think I've ever heard that anywhere else and it's really interesting.

[Outpost75]

I'm interested in any information you can share.

Their .357s can't last more than 1500 rounds without work? I don't think I've ever heard that anywhere else and it's really interesting.

15MB of .pdf files on the way to you.

[Scrounge]

So... the major difference is of material, and the second difference would be amount of material? Not necessarily a difference of design then?

You're missing that the treatment of the metal, and quantity of metal, is part of the design. A kind of steel designated 4130 is frequently used in firearm's, among many other things. It's a chrome-molybdenum alloy, with those materials and probably some others as well, in addition to the iron and carbon that make steel. It can be relatively soft, or it can be quite hard and tough, depending on heat treatment. It's considerably harder and tougher even in its "soft" state than mild steel, which is essentially what most of the older guns were made of. If you want, you can make a part lighter, or smaller, or thinner or whatever, by choosing the right alloy and heat treatment. Or you can make it a lot stronger by using more of the material. All that is determined in the design phase. You can get by with mild steel. Lots of guns have been made with it. You take into account that it isn't as strong as some other materials, and perhaps use more of it. You can get strength in aluminum alloys, too, by adding a metal called scandium. It's expensive, but makes a very light alloy that is still very strong. Smith & Wesson makes guns using that alloy. Again, it's part of the design phase. Glocks are partially plastic. Part of the design includes determining how much plastic it takes, and where it needs to be, to make a strong and durable firearm. Not my thing, but some folks love them some plastic fantastic!

Design is a process. Lots of folks approach it a bit differently, but a poorly designed firearm will be dangerous to user, uncomfortable to handle, unreliable, too bulky, or any or all of those factors, and probably many others. You can just slap some pieces of metal and wood (or plastic and metal) together. It might even work. And it might blow up in your hand. Better to design it for the use you want it to serve. Stress calculations, ergonomics, forces involved, lots of other factors need to be considered.

HTH!

Bill

[El Bibliotecario]

I'm interested in any information you can share.

Their .357s can't last more than 1500 rounds without work?...

After two decades the only required repair for my S&W Model 19 was replacing the cylinder axis pin. Apparently I was doing something wrong.

[Stacts]

15MB of .pdf files on the way to you.

:happy dance: Thanks :happy dance: