The More You Know: Polygonal Rifling

Credit: hkpro.com

Credit: hkpro.com

Back in what now seems like a lifetime ago, I spent a year of my life trying to find a way to match fired bullets with their respective cartridge cases. Because the ammunition manufacturing process involves pressing brass (the cartridge) overtop the softer copper alloy (the bullet jacket), I theorized that the ‘tool marks’ left on the jacket may be unique to each bullet – even after they are fired through a barrel. Using molded casts from the inside of spent casings and comparing them to their respective bullets that had been fired into a water trap, I used a comparison microscope to attempt to identify any possible matching impression and tool markings. Why was I going off on this scientific journey? In part because of Polygonal Barrel Rifling.

In traditional rifling, ‘tools’ such as buttons or broaching bits are used to either press or cut grooves in the bore giving the barrel a defined rate of twist. In polygonal-rifled barrels, the barrel (and hence the bore) is cold hammer forged (or otherwise twisted) creating swells or mounds, also giving the bore a defined rate of twist. That is a very oversimplified view of both types of rifling, but the one important difference is that a tool creates traditional rifling – but that’s not the case in polygonal rifling.

Polygonal_vs_normal_rifling.svg

Traditional rifling (left) and polygonal rifling.

Firearms identification, a broad term used in forensic science to describe the study of what is usually incorrectly referred to as “ballistics”, includes the study of the tool marks left on a bullet from the lands and grooves as it passes down the barrel. Because polygonal-rifled barrels don’t use a tool to make traditional lands and grooves, identifying bullets fired from a polygonal-rifled barrel that was used in a crime is challenging.

image

Using a comparison microscope to compare two bullets with tool marks.

 

image

Bullet fired through raditional rifling (a) and polygonal rifling (b). Credit: Bev Fitchett

On the flip side, the breech face and firing pin leave their own set of unique tool marks on cartridge cases that forensic scientists can use to identify which gun fired a specific cartridge. For example, if you take three pistols and fire ten rounds a piece, a good crime lab analyst can match up all 30 casings back to each respective gun. Not to mention the extractor and ejector tool marks left on casings as well.

Breach face tool marks.

Breech face tool marks.

Now, putting this all together, if a criminal uses a polygonal-rifled pistol in a murder, the forensic scientist working the firearm identification part of the case is going to have the difficult task of positively matching the gun that fired that bullet – remember, no tool marks. However, if my theory panned out, the bullet could be matched with the casing which could then be matched backed to the gun. Bingo.

Not so much. Long story short, although I was able to identify some matches, the tool marks made on bullets by cartridge cases during manufacturing was unreliable as a scientific process. Meaning that it wouldn’t hold up in court.

For shooters, polygonal rifling has distinct advantages over its swaged brothers. For one, the bores create a tighter gas seal leading to higher muzzle velocities, but less lead deposits/cleaning and extended barrel life are also considerations. And like everything in the firearms industry, there is great debate between which is better, traditional or polygonal rifling for precision shooting. As long as it doesn’t have a manual safety, I don’t really care. (Sorry, I couldn’t resist.)

Polygonal Rifling. Forensic Science. Firearms Identification. And that’s The More You Know.

tmyk



Pete

LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Pete.M@staff.thefirearmblog.com


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  • Joe Goins

    The only real drawback to polygonal rifling is that you can’t shoot cast lead.

    • jng1226

      And to add to the lesson here, why exactly is that? I’ve know this since I bought my first Glock in 1992, but I’ve never understood the technical reason behind that instruction.

      • Evan

        That’s something unique to Glock. Neither H&K nor Kahr, who both use polygonally rifled barrels, explicitly recommend against lead bullets. They do both warn that cast lead bullets without a jacket will foul faster than a traditionally rifled barrel.

        • jng1226

          Ok, thanks. So why does it foul faster then?

          • Evan

            Tighter fit.
            Traditional grooves are deeper, so in simple terms the lead “rides” on top of the lands, lead fills in the grooves; whereas in polygonal rifling (the picture up top), the “corners” act as the “grooves” in the rifling, and as the bullet spins, lead tends to collect, the same as it does a traditionally rifled barrel, but your tolerance is much tighter to begin with.

    • jpcmt

      Of course you can. I shoot lead cast on occasion with a Glock 20. The reason jng1226 is that lead can build up and without having lands and grooves for the lead to get compressed in can possibly cause obstruction and maybe a KB at worst and a squib type blockage at the least. Of course nobody can produce a youtube video or photo example in handgun forums, so it’s a myth until proven so.

      • Joe Goins

        The manufacturers say not to. I’ll trust them and not Bubba down the street.

        • zardoz711

          I bet you’re real fun at parties.

          • Joe Goins

            More like: if it blows up and I did something I shouldn’t I have to replace the gun.

      • dieks

        You’re absolutely right!

    • Badwolf

      My old glock shoots cast lead just fine.

      • Joe Goins

        The manufacturer says not to. I’ll take that as gospel over Bubba down the street.

        • Badwolf

          good for you! i know it says not to. but i do anyway, and it does so just fine. im just giving my experience, im not trying to convince you.

        • Budogunner

          There is no threat of immediate failure from shooting lead bullets. Merely that they are dirtier and the lead can accumulate in the shallow ‘gooves’ of polygonal rifling faster than standard if not cleaned.

          Never clean and you can face pressure problems, that’s what they don’t want end users to run into.

          *Not a lawyer, doctor, or rocket surgeon. YMMV, etc.

    • josh

      in my search years ago about this, someone used 100% pure lead in his Glock and never cleaned it, (he seemed to take the “its the AK of pistols” a little too far), and he had some issues with his barrel.
      If you use Hard Cast lead bullets (lead alloys) you’ll be fine all day long, just don’t be stupid, clean your weapon when you’re done for the day.

    • HSR47

      Can’t? Shouldn’t?

      I do, and I haven’t had any issues. I know people who have run literally hundreds of thousands of cast lead bullets through Glock pistols without issue.

      It all comes down to the composition of the lead alloy they’re cast from.

  • El Duderino

    The pro-polygonal crowd, accuracy-wise, is a lot smaller than the pro-traditional rifling. Not saying they’re wrong. I am no barrel maker but from what I understand it’s far easier to create a barrel with the same stresses throughout with traditional rifling.

    • Twilight sparkle

      The confederacy used a rifle with polygonal rifling and some people consider it to be the first sniper rifle. Actually if I remember correctly it was invented by the guy who came up with polygonal rifling.

      • El Duderino

        Well we can be 100% certain it wasn’t cold hammer forged. That seems to be the issue, accuracy-wise. Though the Steyr sniper rifles are made that way and by all accounts are superb. If there is a difference it’s small. I believe the deal is cold hammer forging means you’re mass producing vs. the boutique builders that can hand make traditionally rifled barrels.

        • Twilight sparkle

          It could be argued that hammer forging around a mandrel is more accurate because each barrel would I be manufactured more consistently than that of a traditionally button rifled barrel. You can button rifle a hammer forged barrel but that would add a lot of complexity and increase the chances of giving you an inferior product than a barel that was hammer forged with a mandrel. A lot of the ar barrels that are known for accuracy are made by noveske, fn, and bcm and they all hammer forge most of their barrels, fn having an exception for all of the barrels they made for colt and all of the barrels they made that the us military procured, that was just to meet the technical data package though.

          I remember reading something about current m40s (or another 700 variant) being issued with a polygonal “5R” rifling but I don’t recall if it was hammer forged.

          • Jake S.

            5R, or 5-groove ratcheted, rifling is normally buttoned. I could be wrong about that. The technique is reportedly originated by Obermeyer Barrels. I have limited experience with these barrels having only two of them in my safe. I would like to claim that they are superior to other methods, but as with all types of barrel manufacture, the damned thing can only shoot as well as I can.

          • Twilight sparkle

            Okay, I did a bit more research on it, I guess it isn’t polygonal rifling but it seems to tout the same benefits as polygonal rifling.

          • the_duck

            I wonder about stresses introduced to the barrel during the CHF process. My CZ452 barrel steel sat for over a year outside according to CZ to relieve stresses on the barrel, then it was cold hammer forged which I imagine reintroduced stress back into the barrel. Would button rifling be better in his case? I shoot holes within holes with my rifle, so accuracy is definitely there, but as the stresses introduced by CHF relieve themselves I wonder if this will cause a shift in accuracy in the long run.

          • Jake S.

            I think that, ultimately, you have to worry more about the grooves in the barrel wearing flat before you see any issues from the specific method of manufacture. At the end of the day people tend to put more emphasis on how things are made than they do with being proficient with the weapon system as a whole. The way barrels are made lend more, characteristically, to how and when the barrel starts to perform outside the margins of acceptable “accuracy”; rather if they will. All barrels will degrade in performance with use.

          • Twilight sparkle

            Cold hammer forging shouldn’t really be an issue with stressing the barrel steel, I fact if anything it might make it better, I don’t believe stress itself is an issue in material longevity but more the unevenness of the stresses applied and since chf is done evenly around barrel blanks there should be a more even stress on the material if there’s any stress at all. It’s been awhile since I’ve read up on barrel manufacture and I didn’t get to see much of cz while I was in the Czech Republic but I believe most stress that’s applied during any rifling process should pretty much go away by the time the material has been heat treated and tempered

          • dieks

            Ratcheted: thats another term that has been completely ‘invented’ and is so far of the mark that its no longer funny anymore, lol!

          • US military contract guns don’t have to “just meet the technical package”.

            They have to meet the technical package *exactly*, or they are a contract violation. Even if the manufacturer has a better way, in order to use it, they need to get an approved DFS (Departure From Specification).

            That’s why milspec isn’t always the best spec – milspec *doesn’t allow* innovation – if the milspec says to use 1960s technology, you have to use 1960s technology. If it specifies cut rifling, you have to cut the rifling. If it specifies an alloy that was best in 1975, then even if a better alloy was developed in 1976, you have to use the 1975 stuff.

            Now, you can change the milspec to incorporate innovation, but it’s a PITA to get all the stakeholders to sign off on it.

        • Twilight sparkle

          The issue with accuracy regarding hammer forged barrels could revolve around the fact that most modern rifle barrels that are hammer forged also get chrome lined and that adds a lot of inconsistencies in bullet to barrel contact. If you found a qpq barrel that was hammer forged I doubt you’d see any accuracy issues.

          • dieks

            Just take a quick look at the inside bores of any precision ‘Hammer-forged’ Heym brl and you would wet your panties! In order for any US or other mfg’rd brl; be it buttoned or cut-rifled brl’s, would have to lapp the s***t out of their brls to come even remotely close to their standard bore-finnishes, with very little or no induced stresses left in their brls and a hardness of at least twice the rate of any other brl-steels! Go figure: the very reason there is no need for any ‘Cryo’ treatments’ or Chrome-lining of any proper precision ‘hammer-forged’ brl’s!!

        • dieks

          For your info: I’m an old-time European trained gunmaker and can tell you from experiences that the myth of especially EU-Mfg’rd hammer-forged brl’s being in-accurate due to ‘so-called’ unduced stresses is just a plain old American Brl-makers ‘hoax!

  • jng1226

    Very educational and funny with the NBC PSA meme!

  • Schnee

    My super stealthy polygonally rifled HK P9S leaves no evidence of what shot it…..except that every spent case is covered with burnt lines from the flutes broached into the chamber. It’s easy to spot HK brass. Maybe that’s why the only bad guys shooting P9Ss are villains in movies.

    • noob

      Wasn’t there a thing called a “Miami” barrel that has little bumps unique to the barrel put inside the polygonal rifling to identify the weapon? I think glock made them. I kinda recall tfb did an article on them a while ago.

      • Pete M. – TFB Writer

        Yes, I included it as a reference article. At the top eight.

  • Christian Hedegaard-Schou

    Uh oh.. Someone call Ruger! They utilize hammer forges for almost all their barrels, even though they are traditionally rifled.

    Guess we can’t identify those bullets!!

    • Pete M

      Uh oh is right.

    • Martin M

      You can hammer forge a barrel blank with or without a mandrel. Without a mandrel will need to be bored, and finished with a button or other rifle cutting tool.

      • And you can hammer forge with a smooth mandrel, and avoid boring, but still have to cut rifling.

  • Rob

    I think it is incorrect to say that polygonal rifling requires hammer forging. It can also be done with a button. The barrel on my Kahr pistol doesn’t show any evidence of hammer forging. Polygonal rifling isn’t really any different than conventional rifling, it is just has a different cross sectional pattern. Instead of steep steps up and down it uses a smooth transition. It still deforms the bullet the same as conventional rifling. The deformation is just smoother and more subtle.

    • Evan

      Kahr pistol barrels are in fact hammer forged on their P series IIRC, and conventionally grooved on their CW series.

    • Pete M

      Didn’t necessarily mean that polygonal rifling requires hammer forging. It’s just one technique.

      • Thinking about the stresses involved in cutting the rifling, it seems like it would be a LOT harder to accurately and consistently *cut* polygonal rifling than to form it on a mandrel.

        Probably also easier to cut well defined grooves than polygonal cross section, easier to mandrel form polygonal rifling than distinct grooves, as I thinking about it (but I’m not a rifling production expert).

  • jpcmt

    So I’m curious… What popular handguns use polygonal barrels other than Glock?

    • Evan

      Off the top of my head, Kahr, H&K, CZ, Glock as stated, Magnum Research, and Tanfoglio.

      • ZQuel

        CZs use traditional rifling.

        • Dan

          Not the older models

          • Twilight sparkle

            I’ve seen two people I work with freak out when they both got a CZ 82 and thought it was shot out.

    • Rnasser Rnasser

      Glock barrels are not polygonal…. they just use rounded rifling.

      • jng1226

        According to Glock’s own website, their rifling is “hexagonal”

        • Rnasser Rnasser

          While not technically correct, it makes it easier for the masses to get it that it has a “rounded” internal profile…

          • Twilight sparkle

            What do you mean by a rounded internal profile? That to me sounds more like a barrel that’s been shot out.

  • Marcus D.

    I don’t really see the point in polygonal rifling for pistols. It is supposed to be more accurate, but how accurate do you have to be at 7 yards?

    • iksnilol

      Maybe stop shooting at 7 yards?

      I never understood the guys shooting at such short distances. At least go for 15 meters.

      • Marcus D.

        It is kind of the standard maximum “self defense” distance, which in turn is based off the Tueller drill. The Tuller drill establishes that a man with a knife can get to you in about 1.5 seconds from 21 feet. which is the time it takes to draw and fire. Engaging beyond that distance raises questions as to whether the victim is in immediate threat of serious bodily injury or death. Add to that, the majority (and I recall that it is a substantial majority) of self defense shootings occur at “bad breath” distances of one to three feet. Hence my comment. Traditional rifling will get you on target pretty reliably at 25 yards, although the spread may be wide, and you really don’t need to be (or pay the price for) more accuracy than that unless you are a competitor.

        • If you can reliably make good hits in good time at 15 or 20 meters, you can likely make adequate hits in adequate time at 7, under stress.

          The reverse is not generally true.

    • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

      Not every shot is at 7 yards. Sounds like you need a smooth bore

      • Marcus D.

        Few SD shots are over 15, 25 exceedingly rare, and only one I know of–which was an amazing shot–at close to 100 with a 9 mm. (My son and I tried to hit a target with a 9 mm at 100 yards. We got close a few times, but not once hit the target.)

        • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

          Can’t hit a target at 100 yards 9mm. You need more practice. While you’re correct that most encounters take place close, I also practice at distance with both handguns [25, 50, 75 and 100 yards] and 500+ for rifle. Can’t do the rifle regular as i have to drive a distance to get to a long rifle range but I have 100 yards in the back yard.
          It’s all about proficiency.
          Guess it’s personal preference but if all the shooting you do is at short range, your not acquiring all the skills I believe you need.
          Yes, distance may be rare but I plan to be good enough at distance with all my weapons to cover those rare occurances

          • Marcus D.

            Nonsense. A handgun is not a 100 yard weapon. (Yes, I’ve seen Miculek hit a target with a 9mmm revolver at 1000 yards, but he is hardly in the same class as the rest of us.) I cannot imagine a scenario where I would have to shoot a handgun accurately at that 100 yards, so cannot imagine having a need to be proficient at doing so. That is rifle range. Heck, in the Civil War, 50 feet was rifle range. (Very scary that.) And 500 yards for a rifle might be nice if you hunt (which I don’t)–but it is hardly self defense range. And I couldn’t care less about a SHTF scenario, since I am old and gonna die anyway when my drugs run out.

          • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

            You keep talking about self defense range and you say a pistol isn’t a 100 yard weapon. What I am telling get you is you better be able to make do with what you have.
            I am approaching 60 myself. I used to think that was ancient.
            Sorry to hear your ill.

          • Jethro

            Probably not ill, but like me at 64 I need certain drugs to correct for ones my body doesn’t produce. You are right about making do with what is at hand. I too will die when the drugs run out but I want some company for the journey. I came into the world screaming and covered in somebody else’s blood, no problem leaving the same way if nessary.

          • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

            Jethro, I am with you. I am taking some meds too. I may not die from the lack of it but living will suck.
            I plan to protect my home and family, no matter what. And you’ve got the right idea. When I stand in judgement, I want to be surrounded by those trying to harm my family.
            I don’t understanding why Marcus thinks hitting a target at 100 yards is such a big deal but then the smallest main carry I do is a commander size Springfield. I can hit a B27 target within the 8 ring or better with a 6.5″ M29 [6/6]. With my commander, I can hit it 7 out of 8. It isn’t magic, it’s practice. From a rest, I can do reliable head shots with my 29.
            I have 9mms because ammo is so plentiful.
            And Jethro, get a go to supply of drugs in addition to your regular Supply but somehow I think you already have that covered. A sympathetic doctor doubled my meds long enough for me to sock away a 9 month supply , plus my regular 90 days gives me almost a year. I realize that some doesn’t store as long.
            I am too old to run but that doesn’t mean I won’t be a real pain to ner’do’wells.

        • iksnilol

          My logic is simple: If I shoot well at 15-25 meters, I should be able to hit something at 7 meters. On the other hand, if I shoot well at 7 meters, I am not guaranteed to shoot well at 15 or 25.

  • iksnilol

    THAT’S WHY CRIMINALS USE GLOCKS!? Not only are they undetectable by scanners, but also leave no evidence of somebody being shot.

    • PK

      Those stealthy, porcelain Glock 7s are the biggest threat, obviously. At least very few crooks have them, since “they cost more than you make in a month.”

      • Michael R. Zupcak

        Plus the Glock 7’s are made in Germany instead of Austria, according to the movie 😉

        • PK

          Obviously it’s been too long since I’ve seen the Die Hard movies! I’ll have to watch them during Christmas time this year…

      • squareWave

        That’s my favorite, right up there with Lethal Weapon 3 which taught us a teflon coated bullet can zip right through a bulletproof vest, or even the thick steel of a bulldozer bucket.

        • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

          I loved the depleted uranium pistol bullets that went thru bunches of steel but we’re able to be pulled out of James Bond and reassembled. So many errors on that on

    • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

      I detectable by scanners? Missed the movie reference/ sarcasm flag on that one

      • iksnilol

        Glocks are made out of plastic, airport scanners and such can’t pick them up. Put a Glock in your pocket and just walk right through a metal detector without issue.

        • chris topher

          Can I come watch you get arrested for trying that ?

          • iksnilol

            Why would I get arrested?

            I mean, sure, I am a muslim and have a shady name but the invisible Glock shouldn’t cause issue.

          • chris topher

            first of all it is not invisible there are METAL parts ie: slide , sear, springs

          • iksnilol

            Nah, that’s what they tell the public to ease minds. I mean, that’s why they don’t have cut rifling, the plastic would warp.

          • chris topher

            Have you actually held a FULLY PLASTIC GLOCK in your hand or just read about it?

          • RocketScientist

            Hey Chris, buddy, you must be new here. Iksnilol is trolling you. He is a pretty knowledge, if often annoying, gun guy. I’d bet a whole crate of 6.5×55 brass that he is fully aware of the metal content of GLOCK brand glock pistols.

          • chris topher

            TY

          • iksnilol

            6.5×55 brass? Oh my.

            In all seriousness tho, Glock did make a cheap and disposable all plastic silencer intended to be used on their pistols.

          • iksnilol

            I’ve operated with one several times in foreign operations. Even the silencer is made from plastic to help with remaining undetected.

          • L Cavendish

            the bullets and casings as well…

          • iksnilol

            Exactly, Glock brand Glock ammo is the premier for assassinations.

          • CountryBoy

            I get my bullets from a company in Wisconsin. They’re made of cheese, don’t show on scanners, and can be eaten if I’m in a jam.

          • Dude, he’s riffing off the second Die Hard movie and the hysterical claims of magic that gun banners bleated when the Glock hit American shelves.

          • CountryBoy

            Chris,

            That thing called a “barrel” is still made of steel, at least in mine. I haven’t upgraded to the “superspy” version with the proflowed unobtanium barrel yet. Thus, it shows quite well on scanners, just like countless artificial joints in humans.

            Iksni is pulling your leg, or something.

          • iksnilol

            Nah. they just coat it with something shiny so it looks like metal. I’m 100% serious, Glocks were first made for assassinations across the globe.

          • CountryBoy

            Prototypes came with a spare tube of silverback gorilla snot, which, while effective, was very hard to get.

          • John Yossarian

            These days, being Muslim and having a shady name means getting an express pass through security.

            Every moron is so afraid of being called a racist, that we aren’t allowed to protect ourselves from patterns of crime.

          • iksnilol

            From personal experience, not really true.

            It’s kinda the reason I don’t like air travel.

        • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

          I am with the guy that wants to watch you try it. Are you Norwegian?

        • CountryBoy

          Also, if you close your eyes while walking past the TSA lines through to the airport gate, no one will see you!*

          * (your mileage may vary when using this trick!)

          • iksnilol

            That’s why we’ve been fed the lie that you shouldn’t wake sleepwalkers. They’re actually highly trained govt operatives.

          • CountryBoy

            And they learned that skill from toddlers, who realize at an early age that running from trouble with their eyes closed makes it so parents can’t see them.

          • iksnilol

            Nice to see a fellow trained operative on these forums. Too few of us.

          • CountryBoy

            There may be more, but they’re undercover!

          • iksnilol

            Maintaining OPSEC, smart.

          • CountryBoy

            We’re required to do so by the rules issued from NINCOMPOOP.

        • Dragonheart

          Assuming the whole Glock gun was polymer, which it’s not, and assume it can’t be detected, which it can. Exactly where do you acquire the non-detectable no-metal component ammunition? Oh, from the same place as you got the imaginary gun, I forgot we were playing let’s pretend.

          • iksnilol

            No, I get my ammo from Glock.

            Maybe you civilians can’t get it but professional assassins and military/LEOs can get them easily by contacting Glock.

          • CountryBoy

            Nothing sticks to it either – not fried eggs, burned bacon or monkey bread!

            But in the reviews it was generally panned.

          • iksnilol

            That’s why it goes through armor, the bullets don’t stick to the armor.

          • CountryBoy

            The latest version, with “OMW” (“outta my way”) even has little fingers on the nose of the bullet to move Kevlar fibers out of the way, allowing the rest to go on through easily too.

  • Tom

    BREECH!

    • Pete M. – TFB Writer

      Thanks Tom. Corrected.

  • Fred Ray

    Polygonal rifling was invented by British engineer Joseph Whitworth, who also pioneered the basics of long-range shooting — long bullet in relation to its diameter spun in a very fast twist (1-20″). WW used a mechanically-fitted .451 bullet in a twisted hexagonal bore instead of conventional rifling and an expanding bullet like the Minie. It also gave faster velocity (less friction) and allowed him to use a harder bullet, which gave better penetration. WW made his own rifles and some of them were used by the Confederacy in the American Civil War as sharpshooter rifles to great effect; many more were used all over the empire as match rifles, where they were consistent winners.

    WWs design was overshadowed by around 1870 by newer and more conventional rifling systems like the Henry and Metford, which also used harder bullets. It was, however, a giant step forward in firearms technology, and it’s interesting to see his rifling system revived.

    • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

      Thanks for the info. Nice post

    • noob

      Interesting – did Whitworth use hammer forging and a mandrel?

      also how the heck do they get the mandrel out of the finished barrel after hammer forging without damaging the mandrel or the barrel?

  • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

    No other sure I would rely on the engineering prowess of a group that can’t spell “bullet.”
    😀

    • Jeff Suever

      I would. It’s intentional to separate it from those godforsaken “j-words”. 🙂 Boolits= as God laid it into the soil. Grand old Galena, The Silver Stream graciously hand poured into molds for our consumption. . . Bullets= Machine made utilizing Full Length Gas Checks as to provide projectiles for the masses.

      Anybody can be a bullet stuffer. Throw alloys, fit and an infinite number of lube recipes and now you’ve got some variables to play with.

  • Shocked_and_Amazed✓ᵛᵉʳᶦᶠᶦᵉᵈ

    Pete M.,
    Thanks for the article

  • joeyskylynx

    Would it be possible to use polygonal rifling with a .22LR that only uses stuff like CCI Green and CCI Copper?

  • me ohmy

    same can be said for marlin microgroove barrels….VERY hard to match

    • Pete M. – TFB Writer

      Thanks

  • Benjamin Goldstein

    You know Tom Hall over at DME Tool ( he makes probably 80% of the worlds rifling buttons, Hammer Forge rifling mandrels ) Does make a polygonal-rifle Pull or Push through rifling button..

  • 2ThinkN_Do2

    Most accurate firearm I own, polygonal barrel Kahr MK40, after that, CZ75B; that is when talking semi-auto.