The Best of WeaponsMan Gun Tech

We’ve been asked for a better way to find the best of our technical posts. And we’re going to put this page up, and, we hope, keep it updated, with some of our best Gun Technical themes. We’re also adding a Gun Tech category that will let you distill the blog down — however, we have almost 2,000 back posts to go through and classify.

Technical Articles

The US Army Examines the AK

The US Army early and often applied technical intelligence techniques to the Soviet AK-47 and its Chinese clone, the Type 56. We’ll try to follow this through some 50-year-old once-classified reports, of which we’ve posted the first.

  • The US Army Always Respected the AK. This post examines a once-Secret 1964 Foreign Material Exploitation Report comparing a recently-acquired Chinese Type 56 version of the AK-47 to a Soviet-made rifle that had been in Springfield Armory’s possession for some years. Now with a free link to the declassified file at Small Arms of the World. The file provides some information on milled AKs that you won’t find in many other sources.

The SAWs that never WAS

The 1970s Squad Automatic Weapon program of the US Army, examined from the viewpoint of the last, 1978-79, multi-contestant competition.

  • The SAWs that never WAS: Intro, and XM106. This introduces the series, and the ugly duckling of the competition, a bizarre M16A1 variant with quick-change barrel, but still magazine-fed. Published 28 Oct 13.
  • The SAWs that never WAS: Part 2, the XM-248′s forerunner, XM235. The Rodman Labs XM235 was a radical reconception of the light machine gun which was designed to increase accuracy and reduce unintended dispersion on target. We mention in passing its abandoned XM233 and 234 competitors, all chambered for a 6.0 x 45mm cartridge. Published 31 Oct 13.
  • The SAWs that never WAS: Part 3, XM248. Rodman couldn’t go to production, so the commercial makers of the XM233 and XM234, Philco and Maremont, competed for the contract. Philco (later Ford Aerospace) won, and began to make changes to the XM235, as requested by the Army, producing the XM248. Published 2 Nov 13.
  • The SAWS that Never WAS, part 3b: the feed of the XM248. The ratchet-driven sprocket belt feed of the XM235/248 is examined using the patent documents as a basis. Published 4 Nov 13.
  • The SAWs that never WAS: Part 4, H&K XM262. Heckler & Koch’s entry was initially just a baseline for comparison of the Army’s own designs, but it performed well enough to make it into the final four (with the 106, 248, and 249). Published 9 Nov 13.
  • The SAWs that never WAS, Part 5, XM249. Like the H&K XM262, the XM249 was initially just entered to compare the FN light machine gun to the Army entries, but it ultimately beat them all. Published 23 Nov 13.

M16A1 Technical History

We’d advise everybody to look at Daniel E. Watters’s technical timeline formerly hosted at The Gun Zone, (now hosted at which is a necessary document for orienting yourself in the time domain of small caliber high velocity arms development. But we have looked into a couple of the technical and programmatic milestones in some depth, and will be adding those articles in this section in due course.

What Makes Guns Tick

Here’s where we put our technical articles that aren’t about late-20th Century American military arms.

  • How US WWII Arms Changed Small Arms Forever. No one had ever fielded an all-autoloading army before. No one would ever design a new military bolt action again. Published 9 May 12.
  • A short history of toggle locking. Borchardt, Luger, Maxim, and Browning. Browning? Yep. Published 13 Sep 13.
  • Toggles II: Some we missed, and why toggles? Some toggles we didn’t mention, some of the reasoning behind choosing a toggle lock, why toggle locks went (mostly) extinct, and why and how they might come back. Published 1 Oct 13.
  • Science: Flash Hiders and Accuracy. Australia’s DSTO looks into how a flash suppressor can reduce mean dispersion — and why.
  • 5 Reasons for the AK’s Legendary Reliability. It’s no accident that the long-serving, widely-manufactured Russian assault rifle can take a licking and keep on ticking. We explain some of the reasons, and some of the engineering that went into making it that way.
  • How Accurate was a .50 in World War II? We look at some information the USAAF gathered, and note with some surprise how sustained automatic fire permanently degraded accuracy, even without measurably changing barrel dimensions.
  • A Taxonomy of Safeties. We examine the many different ways of safetying a service weapon over the 19th-21st centuries. Published 23 Jan 2015.
  • Firearms Reverse Engineering. Why you might want to do this; some examples; where to get some help. Published 3 Apr 15.
  • A Tale of Two Temperatures. A look automatic-weapons barrel temperatures via a copy of a temperature graph as published in the Rheinmetall Waffentechnisches Taschenbuch, and that demonstrates how burst count and frequency as well as pause duration between bursts affects barrel temperatures.
  • A Short History of Chrome Bores. This report reviews how the technology of chrome bores was developed. Long before the US applied it, it was standard on Soviet weapons, and before the Soviets used it, it was standard on some Japanese small arms. Published 9 Jan 14; added to this page 13 Feb 17.

Gunsmith Tools & Their Sources

What was meant to be a throw-away post to keep from having that most dreadful of blog calamities, a day of radio silence, wound up pretty good, largely thanks to the insightful comments from The Dyspeptic Gunsmith. In time we will move it (and some wisdom from previous tool posts) into a permanent Page (like this) of its own, but for now here it is.

3D Printing/Additive Manufacturing & Guns

We’ve always been interested in gun (and everything else) manufacturing. The latest major development in manufacturing is additive manufacturing — using machines that build things up, instead of cut them down. We’ll be adding those articles here.

(to be further developed as time permits)


Materials, Technologies and the Future

What drives the development of weapons is, naturally, technology and engineering. And so we’re interested in trying to extrapolate from what’s been done in the past, and what’s in the labs and the higher-tech industries that feed technologies to the arms industry, right now, to what the weapons of the futre will look, sound, and perform like.

59 thoughts on “The Best of WeaponsMan Gun Tech

  1. Gabor Vass

    Dear WeaponsMan,
    as I can’t find an e-mail address on your excellent blog, I have to write a public comment.

    We, the Kaliber magazine, is the only Hungarian printed firearms publication (monthly magazine), and interested about using your ” The SAWs that never was” series as a basis of a future article in our magazine.
    Please give us permission to use your material and photos, strictly in Hungarian language, and in edited (shortened) form, with a link to your blog as source of course.

    thank you in advance
    Gabor Vass
    chief editor
    Kaliber magazin

    1. DR

      I’m writing to recommend that you inform your readers that the recently released film entitled “Midnight Ride: When Rogue Politicians Call for Martial Law” is currently available on YouTube. It is easily the most important film I have ever viewed, on the original purpose of the Second Amendment, and it’s release could not be more timely.

      Thanks for your marvelous website!


      1. Higgins

        Ran across a picture of a pre-war piece of artillery referred to as a “Punt Gun”. Said to shoot a 16 ounce bullet. Thought it may be of interest.

  2. Yank lll

    To be homest I dont remember.. I think it may have been in the war college archives but cant verify it.
    I was hacking the web addresses on .mil sites to go backwards from another file while searching for files on the M4 and found that one completely by accident. I knew the AirForce had done testing on the Stoner design in the early 60’s but never anything about the Army testing it at all that early especially in 7.62.. I remember the M-14 mods in the T series but never that one.. it definitely belongs here for sure.
    My pleasure

    Yank lll

    1. Hognose Post author

      Yank —
      There’s some on the Army testing of the AR-10 (very little) in Random Shots: Episodes in the life of a weapons developer by Roy E. Rayle. Rayle was an Army ordnance officer; Random Shots is a posthumous memoir published in 2012. Most of it is about the M14 and M60 programs. At first, the T44 (future M14, an improved Garand with a better gas system) was far superior to the T47 (all new design) but inferior to the FN and to the control M1. What saved the T44 was the cold weather tests; Rayle and the guys at Springfield Armory worked overtime getting the T44 ready. In the cold weather tests to -65F, the T44 curb-stomped the FN. Overall, the weapons were close enough that the Army ordered troop tests (and manufacturing cost evaluation) with 500 each T44s and T48s, an American-made FN which was made by H&R. The rifles were found to be roughly equivalent with the T44 having an edge; they could as easily have bought the FN, which most other NATO armies did. The biggest beef Ordnance had with both weapons is that they were hard and slow to reload from above with stripper clips; they were actually looking at saving money by giving Joe only one magazine!

      Often times ordnance buys hinge on stupid things like that. The Krag got the nod in 1892 because it had the best magazine cut-off of any of the magazine rifles tested, and commanders didn’t want the troops wasting ammunition by firing it at the enemy! (The same brain-dead sentiment drove the 3-round-burst mechanism of the now obsoleted M4 and M16A2).

      Rayle’s book is a very good inside look at the M14 and M60 programs from a partisan of the in-house design. What he says about the AR-10 is that it came to Army attention through one of the branch boards, not the Ordnance corps, and by the time it was tested the service was pretty much committed to the M14, which had much less impact on the training base due to its similarity to its pappy, the Garand. I was surprised to see how much more reliable both the M14 and the T48 were, in the final test, compared to the control M1s. (I was also surprised to hear how well the H&R contract on the T48 went, as the company struggled with both M14 and M16 contracts later). According to Rayle, the AR10 was interesting, but it still showed signs of teething troubles of the sort that both the T44 and FN designs had already overcome.

      1. Daniel E. Watters

        The author of the AR-10 report, Laurence F. Moore, was an interesting fellow. He shot in national and international rifle competitions from 1937 to 1994. Among his credits was winning the 1963 Wimbledon Cup at Camp Perry and membership on ten Palma teams. After receiving a BS in Engineering at John Hopkins, Moore went to work at Springfield Armory in 1940. During WW2 he enlisted, and saw combat with the 10th Mountain Division in Italy. He remained in uniform after the war, and was ultimately transferred to Aberdeen Proving Ground in the late 1940s as a small arms tester. After returning to civilian status in 1950, Moore stayed on at Aberdeen until 1964. At that point, he was transferred to Frankford Arsenal, and four years later, moved on to Rock Island Arsenal until his retirement in 1979.

        1. Hognose Post author

          That’s an unusual resume indeed.

          My dad plays golf with a guy who was a company grade officer in the 10th Mountain, and after the war developed Stowe Vt. as a ski resort (with others, of course). Met the fellow once, he could pass for 20 years younger, quite an incredible guy and still with us (retired in Florida, and he gave up skiing, IIRC, when he turned 90).

  3. Bill T

    I either have misplaced the email address or I never had it. Here is a rather stupid video that’s making the rounds on FaceBook. It is funny enough and absurd enough to touch your funny-bone.

    It’s probably no worse than the “Real Thing” in many departments though. Hope you enjoy it.
    Bill T.

  4. Arturo

    Hey are there any books that you could recommend any books on weapon design? Something similiar to “The Machine Gun” by Chinn would be great as was excellent book.

    1. Hognose Post author

      Arturo, there was a series of Rock Island Arsenal notes on gun design that seemed to be written to bring a novice mechanical engineer up to speed on guns. There are a number of books that go into some depth on an individual design. There are also many good websites. Sounds like a good idea for a new “Page” to go along with “the best of WeaponsMan Gun TEch” (which also needs some updating).

      1. Arturo

        Thanks, i dont suppose you would be able to point me in its direction. I have only found the one made in 1968 and I am not sure that this is extent of the publication. The new page sounds like a great idea.

        1. Hognose Post author

          Yes, that’s the one, Arturo.

          Rocha, John G. Technical Notes: Small Arms Weapons Design. Rock Island, IL: Rock Island Arsenal, 1968. Retrieved from:

          There are also some prewar professors in the US and Germany who published on gun design. Long out of print, but they’ll be in the references page when it goes live. Our preference will always be for live links, of course.

          Post 1968, the Army was much less involved with the detail design and manufacturing of small arms. In 1968, Springfield Arsenal closed. More recently, the BRL “transitioned” to the ARL and at least this time there was a team to ensure that all the knowledge wasn’t lost, as it was in the late 60s.

          Of course, you know about Chinn Volume IV (parts IX and X or maybe it’s X and XI).

  5. Dan

    I do not see a contact email. Would you be interested in publishing a story from Rock Island Auction. I do not see an upload area?

    1. Hognose Post author

      For all, I have replied to Dan and we will be running a release from RIA as a guest post. It covers something big: fakery in the collector gun market.

    1. Hognose Post author

      Cranfield is (or is historically?) the RAF academy. I’ve seen some cool aerodynamic research out of there before (although Glasgow is where the rotorcraft brilliance resides, in my experience). So I’ll really get a kick out of this. A lot of improvised weapons were tried in the immediate aftermath of Dunkirk, where they’d saved an army, but with scarcely the shirts on their backs.

  6. Leatherneck556


    This is an excellent blog. I really appreciate all the info. Since I have been able to locate a contact page or email address, I am posting this question in the comments: Could you possibly do a write-up on the considerations related to Mil-Spec chrome-lined barrels vs. stainless steel barrels vs. melonite-coated barrels, etc.

    I ask because my normal internetery has always shown me that chrome-lined are, in your words, “Durability optimized” and SS barrels are “accuracy optimized”. How are those gaps nowadays that salt-bath nitriding has risen to prominence? What about the use of alternate steels like Bravo Company’s SS410 barrels?

    I personally prefer a slightly-heavier-than-GI barrel, a mid-weight barrel if you will. I am mostly a high-volume shooter that focuses on ranges 400m and less, rather than a precision shooter, but I have often wondered about a mid-weight SS410 barrel – possibly with melonite coating – as a sweet spot for accuracy, barrel durability, and heat resistance. In short, it seems to me like such a barrel could be the best “all-around” AR15 barrel one could find. Could you possibly elaborate on all these considerations when it comes to barrel construction in the AR15?

    Thanks a lot!

    1. Hognose Post author

      Funny you should mention this. I was just thinking about coatings this morning before getting caught up in the stuff that’s going on. In part because there’s a great coating shop not to far from where I am. I was thinking about calling them monday for an interview if my schedule permits. Because I don’t know the answer to some of these questions myself. Chrome has been the gold standard for durability, but chrome dates to 1925 when Olin (IIRC) patented it. The Japanese used chrome plating to make up for high-chromium and other strengthening-metal alloys like vanadium and molybdenum. So it’s possible that a new tech is better for one thing or another. Let’s keep open minds and ask the experts!

  7. eric

    I’ve looked around for the answer to this on the web but nothing really definitive so I thought I’d ask here (just found the blog): The conventional wisdom is that the AK is more reliable in adverse conditions (including lack of time to clean) and the AR is more accurate. My question is, how much of that reliability comes from the gas system vs how much comes from the looser part tolerances.
    Another way of asking is would a Gas piston AR have similar reliability to an AK built to the same part tolerances?
    The latest round of AR vs AK debate seems to have manifest in rifles like the SCAR, ACR and HK 416, but they use a short stroke system which from what I can tell trades a bit of reliability for less mass movement during shooting compared to a long stroke.

    1. Hognose Post author

      In the real world, my experience was that the accuracy difference was real (but perhaps not material at infantry ranges) and the reliability difference isn’t, really. AKs can tolerate abuse ARs can’t but that’s also design and materials. The ergonomics of the AR are far superior. And you’ll notice that the controls on novel clean-sheet designs are usually close to AR specs, usually today with ambidextrous controls and maybe a better positioned and ambi bolt catch / release. Even the Galil, an AK copy, provided an M16 type as well as an AK type selector lever, and that was 40 years ago!

      One of the big things driving those piston ARs is better adaptation to a range of back-pressure, to wit, operating with and without a suppressor. M4A1 works OK with the KAC suppressor but the cycle time goes way down (and therefore, if you fire it on auto which we usually don’t, especially suppressed, the cyclic rate goes way up). The guys that sponsored the 416s wanted to run them suppressed and have the full-auto option if needed.

      1. eric

        I interpret your reply to mean that with at least minimal maintenance, AK and AR reliability isnt too different. If you keep the AR bolt lubed and reasonably clean, it’ll be ok. Although a comment from a soldier quoted in a long ago article comes to mind “yes, but sometimes you need it to run without cleaning too” which I take to mean that sometimes situations dont allow for proper maintenance, and in those cases piston guns dont reach their limits as quickly. I recall reading of time or two in Afghanistan where M4s were stressed beyond their design limits during intense firefights where a piston gun might have performed somewhat better. It’s also possible those fights went so far beyond the limits that it would not have mattered, as in at least one that I recall the M4 was being used as a SAW for an extended period.

        That may be the heart of why the army brass keeps saying that piston designs like the SCAR/ ACR/416 are not sufficiently superior to the M16/M4 family, although the raw numbers from the testing seem to indicate a very noticeable difference.

        1. Hognose Post author

          The numbers that have been publicized from tests have not been apples and oranges, either.

          Any AR is limited to about 400-500 rounds on continuous automatic. The point of failure is the barrel, the cause of failure is heat. AKs set their handguards on fire at about that point and blast on for a while, but I don’t think you’ll get to 1000 rounds without destroying the gun. By the 300-round or so point, the rounds are not going anywhere near point of aim because the barrel is hot enough to be flexing madly; in fact, velocity drops off as hot gases squirt around the bullet.

          I’ve written pretty extensively on heat management, and it’s in most of the references (complete with equations) on the Design References page. It’s a two part problem at least — how fast does the barrel heat up? And how fast can it shed that heat? That’s why HMGs used to be liquid cooled (even there, there are limits; your coolant boils off) and then GPMGs have interchangeable barrels.

    1. Hognose Post author

      Thanks Eric, I exposed the link for the benefit of the readers, your email address is protected. I need to put an email address on the site, it’s not like I’m deeply stealthed….

  8. Kerodin

    Sorry if I am posting this in the wrong spot – do you have experience with/opinion regarding the Fulton Armory M14 builds?


  9. john jay


    what earthly good would it do for any soldier in any kind of combat to fire 300 rounds in quick succession? firing that many rounds does not lend the implication that such a soldier hit a damned thing with any rounds before firing off no. 300. if that is the case, what is the likelihood that no. 300 is gonna do much good?

    as to firearm function, ak-47 versus the m-16/m-4, and all that.– 1.)i don’t know how many cartridge models the army has shot through the stoner platform, but it seems that a 55 grain bullet has been used, a 62 grain bullet, a 69 grain bullet, and now a 77 grain bullet is being deployed, and i’ve read of experimentation with heavier weights that that. 2.)the stoner system has been shot with long barrels, short barrels, intermediate barrels and heavy profile and pencil profile barrels, necessitating the use of gas blocks located at long, short and intermediate locations. 3.)how many powders have been used as propellant w/ the stoner system, and what are the burn rates, energy yields and pressure curves of the same? anyone know? 4.)to the best of my knowledge, the ak-47 rifle has been shot w/ a 123 grain bullet at around 2350 fps muzzle velocity, out of rifles basically w/ similar barrels and gas systems of a given length. i am assuming, but do not know, that the propellant has remained constant. 5.)in short, don’t fix it if it ain’t broke.

    given all of this, it is a fantastic testimonial to the basic design and mechanical virtue, incredible versatility and incredible reliability of the ar-15/m-16 that the damn thing works at all. instead, those ignorant of the incredible balancing act necessary to make any semi-auto weapon work call the poor abused rifle system the “jamomatic,” and other stupid epithets. reflect for a moment, that it took 16 years to get the m-1 sorted out, and that the germans never really got the semi-auto fully lined out from start to finish of wwii.

    i venture to say that had the ar-15 enjoyed the same “stability” over its life time its reputation would not be so sullied by “the critics.” as a matter of fact, most modern design efforts in the last 50 years or so have been “guided” by the ar-15 and ar-180 systems, which has to be testimony to something.

    john jay

    1. Hognose Post author

      Well, the AK did undergo some mods and changes, a caliber change in the 1970s, numerous adaptations of stocks and accessories, lengthening to squad-automatic size, shortening to SMG size, some nations (not Russia) made a sniper rifle of it, Kalashnikov’s own design bureau did an FN-MAG in that they flipped the action and put a belt feed on it, yielding the PKM (FN flipped the old BAR to make the MAG). It’s been made as a bullpup and parts of its mechanism have been used by hundreds of imitators and extenders over the years. Some of those mods were well-engineered, some not so much, but the basic system’s pretty adaptable.The AK has some of its own virtues like an indestructible (nearly) if heavy magazine and such heavy reciprocating parts that it can deal with great variations in ammo quality.

      But it doesn’t have the key advantages of the Stoner system: light weight, straight line, controlled recoil, and modularity. The modularity has since really exploded, but there were people doing things with it in the 1970s already, and Colt kind of showed the way with the variants of its “CAR-15 system” of circa 1967.

  10. john jay


    i didn’t know about all that stuff. i knew about the ak-74 changes, but had no idea that the other experimentation had been going on. neat. well, i knew about the squad machine gun & sniper rifles, basically upsizing of the basic platform to scale to handle the battle rifle 7.62.

    any of that stuff go into production and/or get fielded?

    by the way, thanks for your attention to my little project. it has been very much appreciated. i received quite of a bit of attention through your link. finally, i have a 1941 edition of “automatic arms” by melvin m. johnson, jr. and charles t. haven which discusses automatic weapons design (very ably, to my mind), and the use of the automatic arm in military tactics and strategies. it has some wonderful fold out schematics of many auto & semi auto firearms.

    it’s a good read.

  11. Nick Nichols

    Listening to you talk about your ankle in your recent Florida post has me wondering if you’ve talked to your doctor about any of the new ankle replacement surgeries that have become popular in the last several years. I have met someone that had it done and they seemed pretty impressed with it.
    Thank you for such an excellent blog and also thank you very much for your service.


  12. Keith

    Enjoying reading all this. Thanks to all the posters. Merry Chritmas and God’s grace and peace be with you and yours this holliday season.

  13. John h.

    About 10 or more yrs ago i acquired a Armscorp m 14 style from Jack at Armscorp before he sold out and passed on. He was cleaning out his safe before passing and i had talked w/ him and purchased, directly from him since it was his personal rifle, what he said was one of the first, if not, the first rifle from the orig factory at Silver Spring, MD. Its ser no. A10000. Ive looked all over the web and talk w/ everyone about the ser # but no one has any record of it. Could i actually have the first Armscorrp rifle??

    1. Thomas

      Hi, I worked at the subcontractor that machined the recievers in Beltsville Maryland. We also did some FN FAL work for him. He supplied the raw stainless forgings and we did the rest, I got quite an education, very difficult to make. I can try to track down the guy that was in charge and doing the numbering, he is in China now.

  14. Lyndon Ebright

    Hi, I’m trying to track down an Australian Gunsmith by the name of Tony Small. I ran across his article on a Lathe Rifling attachment he made for a metal lathe at this website:
    There was a couple of links ( in this article, but they seem to be Chinese, or something like that (nothing I could understand!!)
    If you know his whereabouts or know how to contact him, I would be very interested in talking with him.
    Thanks in advance,

  15. haze gray

    Off Topic. Sunday’s Washington Post had a long article on a Green Beret, Nathan Ross Chapman. If it’s of interest and you haven’t seen it; I’ve copied the first few paragraphs below as I can’t seem to get a link to their site. If you can get into the Post, search for Thomas Gibbons-Neff and “CIA honors Green Beret…” If this doesn’t work I’ve got rest of the text saved and can forward that if needed. It’s a remarkable story about a good man.

    After 13 years, CIA honors Green Beret killed on secret Afghanistan mission
    The Washington Post.
    Thomas Gibbons-Neff
    Sunday, April 17, 2016

    When Nathan Ross Chapman became the first military casualty to die by enemy fire during the war in Afghanistan, the only American flag available for his casket was a patch torn off the uniform of an airman loading his coffin for the long trip home. He was buried on Jan. 11, 2002, a week after his death, with full military honors in Tahoma National Cemetery, Washington.

    It took another 13 years for the CIA to recognize on its Memorial Wall that Chapman, an Army Green Beret, was also one of its own — the sergeant first class had been officially detailed to the agency in the weeks after the 9/11 attacks and died acting as a CIA paramilitary team’s communications specialist.

    Chapman’s death was a watershed event for a country that didn’t know it was headed into a seemingly endless war, where the news of those lost would turn into a kind of white noise for many Americans. The first of its kind in Afghanistan, his death drew national attention, including a televised funeral.

    1. Hognose Post author

      Yeah, this is on the To Be Written About list with a million other things. Most of us who were in SF at the time have known all along but, well, they were keeping it secret for a reason. There are an awful lot of reasons that an operation might not be overt as an intelligence agency operation. Many of these have to do with the sensibilities of friendly foreign services.

      His funeral was quite a show, people turned out for miles with flags to salute his passing, according to an SF vet who was there.

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  17. Josey Wales

    RE: The SAWs that never WAS: Part 4, H&K XM262 in “The Best of WeaponsMan Gun Tech”

    “After the HK11/21, the company redid the whole thing as the HK13/23 in 5.56mm. These guns used the smaller receiver dimensions and parts of the 5.56mm rifle.”

    This is not correct, the 21E and the 23E are the same gun/receiver, the barrel, BCG and feed mech can be swapped to give you a 7.62/5.56 convertible gun. Factory guns (as opposed to American made sear hosts built from parts sets where the builder marks them as such) are not marked 21E or 23E on the receiver, just an “Hk”, an Oberndorf proof stamp, and a serial number on the spine. The feed mech is marked 21E or 23E, as is the bolt carrier. Some times the actual bolt head will be, but not always, I have seen 23E bolts that were and those that aren’t. The 5.56 barrel I have is only marked with caliber, twist rate, and proof mark.

    I wish it WAS correct, a 5.56 23E built on an Hk 33/53/93 sized receiver with a “K” length shroud would be shorter and more accurately resemble the SAW concept. That said, a 7.62/5.56 caliber convertible belt fed is bad ass in it’s own right.

    Also, the factory 23E bolt head uses titanium half moon rollers rather than full rounds of steel. Why I have no idea, HK sometimes does things that make sense only to the designer but suffice to say the concept doesn’t work, roller wear and bolt gap issues if not actual damage by 5K rounds are the rule and the replacement rollers are expensive/hard to come by. The premier builder of these guns is Mike Woodward at TSC Machine, he modifies regular 33/53/93 bolt heads with round rollers for his 23E builds and his customers routinely get 20k rounds before needing to replace the rollers with the next size up to compensate for wear.

    1. Hognose Post author

      Awesome information, and many thanks for the correction. As you might surmise I haven’t handled one of these personally (only a regular 21, and that years ago, in the service where it had a specific application). People have asked me to extend the SAWs thing to a book. but people out there know more about the subject than I do. You and Mike Woodward, for instance.

  18. Franz Shoaf

    Hello-I am new to your site. Glad I came across it. Was wondering if we knew each other. I am also retired SF 11B/C/F/ Tm Sgt and am now a gunsmith in San Antonio. Was on RT Nebraska in Kontum with MACSOG. Am a member of Professional Soldiers site and various Thompson SMG sites. Work on mostly Springfield 03’s and vintage target rifles. Would be glad to hear from some of you-have been out of the net for a very long time. My regards to all of you. FCS

  19. Bob

    I have what might be remnants of a T3 carbine. The stock has a large letter ‘J’ stamped in the sling well, which I read as a supplier of T3 stocks. The stock is all nicked up on the left side just behind the forearm. The forearm is dented a bunch about half way of it’s length, just about where the front of the scope would be. The buttplate and recoil plate are unmarked and the stock has a redish varnish, which I don’t know if it is original or someone stained/varnished it?

    It has a ‘dull copperish looking’ Inland trigger group with the ‘M’ on the magazine release button and unidentifiable manufactures mark that looks like 5 lines with a bar down the middle of the top 3. It has a no mark safety button, and the hammer is stamped (what appears to be) WA.

    The receiver is Rock Ola (Serial 46135XX) with an IBM 8-43 barrel and a type C bayonet lug front band, marked with a Diamond and a ‘D’ inside it.

    Would you have any more information on the configurations of the T#, or know of any other sources.

    Thank you in advance for your time. Bob


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