It Came From 1956: The Double-Barreled Winchester SALVO Rifle

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One of the weapons developed during the early days of small-caliber high velocity research was a double-barreled .22 caliber FAL. This was a follow-on project to the modified T48 (American FAL test rifle) used to test the .22 HV featured in our last Weekly DTIC, itself tested alongside the .22 caliber M2 Carbine as part of the SALVO I Field Experiment. Unlike the earlier T48-based rifle, it fired a different, long-necked “duplex” variant of the .22 HV, with twin 41 grain bullets traveling at 3,250 ft/s. With this ammunition, the weapon could produce four high velocity projectiles with each pull of the trigger, giving it excellent dispersion and theoretically excellent hit probability at expected combat ranges (>300 yards). The disadvantages of an overly heavy weapon due to its twin barrels was not important, as it was intended as a test article only. At 11.8lbs unloaded, it was certainly heavy, though not as heavy as one might expect a twin-barreled semi-automatic rifle to be.

2014-11-16 20_16_00-SPIW The Deadliest Weapon That Never Was.pdf - Adobe Reader

A Winchester cartridge board, showing several experimental military projects. The two cartridges in the middle of the middle row are .22 HV duplex rounds.

This rifle represents one of the earliest operational tests of the “hyper burst” concept. By the time of the ACR program in the late ’80s, this concept had fallen out of favor, as it was determined that while it did greatly increase the hit probability potential of the rifle, the errors induced by the shooter were the overwhelming contributor to misses in combat. Still, the promise of these burst-fire weapons was such that the SALVO, and later SPIW programs would continue trying to realize it in a package that was light, durable, and reliable enough for infantry use.

There is an excellent article on the Winchester SALVO rifle over at Gun Holsters & Gear, but some pics are also available below (image credits for the below images go to AR15.com user armeiro):

Salvo_Rifle_01 Salvo_Rifle_02 Salvo_Rifle_03 Salvo_Rifle_05 Salvo_Rifle_06 Salvo_Rifle_07 Salvo_Rifle_08 Salvo_Rifle_10 Salvo_Rifle_11 Salvo_Rifle_12

H/T to Daniel Watters for the article suggestion.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • Anonymoose

    I want one, and I want it chambered in regular .308. :3c

  • Giolli Joker

    Why my post (showing the three barreled Russian counterpart) wasn’t approved?
    (First time, BTW, that I see the message saying that TFB is verifying the post… new feature?)
    Edit: now it didn’t happen, is it triggered by links? (it was a link to another TFB article…)

    • I approved that post—-
      New feature since we have had entirely too many inappropriate/argumentative post lately. Not even 1 or 2 percent of comments are blocked until approved but from time to time it will happen. There may be a short delay until I approve a blocked comment but it won’t take long.

      • Giolli Joker

        Well… that sucks.
        I mean, not for us reader but for you guys that may have the burden to go through pending posts…
        I’d just suggest to create a quick pinned article to inform readers about the new feature, just so that you won’t get other questions like mine here.
        Thank you, by the way. 😉

        • It is more work for me but I think it’s worth it. I did think about a post like you mention. I’ll run it by Steve since he’ll have to make that decision.
          Very welcome!

    • It’s not by links but I shouldn’t say much about the how. I don’t want to feed those types:-)

  • DiverEngrSL17K

    Interesting rear sight tower, and I noticed the change to a right-handed cocking lever. I’m guessing that the intention was for the ( typically right-handed ) firer to keep the heavy fore-end plus barrels supported with his left arm while cocking and firing with the right hand. This method would also be in keeping with much of the standard training doctrines of the time.

  • The great irony is that it was designed by Stefan K. Janson, the father of the British EM2 bullpup. Janson came to the US after the EM2 was dropped in favor of the FN FAL.

    Another curious convergence was that one of Janson’s coworkers at Winchester was Dr. Karl Maier. Maier is better known for his previous work at Mauser establishing the dimensions needed for the locking pieces in their roller-delayed blowback designs. After WW2, he was brought over to Springfield Armory during Operation Paperclip.

  • hami

    Now this is a rifle that needs to make an appearance in a video game. This would have been perfect in that cold war Call of Duty entry.

  • nobody

    >By the time of the ACR program in the late ’80s, this concept had fallen
    out of favor, as it was determined that while it did greatly increase
    the hit probability potential of the rifle

    If I remember correctly the concept end up working pretty well in the ACR trials, with soldiers armed with the G11 being 50% more likely to hit the target per trigger pull due to its 3 round burst feature, but it wasn’t the 100% improvement that the US Army wanted.

    • I have decided to do an article clearing this up for everybody. Now, to do research!

  • PGConley

    Hey that’s at the Springfield Armory, I was there last summer, very cool place to visit.

  • Giolli Joker

    Welcome back old post o’ mine! 😀

  • Exactly! However, I imagine Janson and Maier worked together with less acrimony than Melvin Johnson and D.M. Williams did when they were both employed at Winchester.

    • Well, of course. Nobody works with more acrimony towards everyone and everything than David Marshall Williams.

      • Johnson had a reputation for abusing testers when anything went wrong with his prototypes. Stoner claimed that he even lit up the Springfield Armory crew when the AR-10 barrel split during endurance testing.

        • Oh yes, Johnson was a huge egotist. He at least did not threaten to shoot his coworkers out of paranoia, though.

          And even if he did, I don’t think the threat would carry so much weight as one from DMW, since he might actually do it!

  • The recoil of three 7.62x39mm rounds firing at once had to be close to that of a dangerous game rifle.

    • A fully automatic AK is handful enough for me!

  • Tassiebush

    Another fantastic article! This concept fascinates me! It has two barrels and two mags but does it have one double faced bolt or two free moving ones? From a reliability standpoint the former might double the chance of a stoppage. The latter would halve it… Well at least leave one operational half. Would also love to see how a mass produced version could have all the barrels regulated to keep both rounds on point of aim. I guess this prototype was to test hit probably and addressing the other challenges would have followed.

    • I believe it is one double-faced bolt, but I have a rule “never talk with certitude about anything you haven’t taken apart yourself”.

  • M198 was a duplex 7.62mm round that saw use in Vietnam.

  • Sid Collins

    There was a movie. Maybe early ’70s. A US veteran is given a double barreled Thompson and placed on an island to hunt down a hold-out Japanese soldier. Can’t remember the name.

  • Ah yes, I’ve seen that!

  • Olin made duplex 5.56mm for Colt’s ACR candidate.

  • Zebra Dun

    It needs something….I know! One more barrel for the Grenade launcher!