# When is the earliest date military technology transfer by time travel should work? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [February 9, 2025, 5:14am UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080 "2025-02-09T05:14:16Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [February 9, 2025, 7:06pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/21 "2025-02-09T19:06:53Z")
> [@griffin1977](#): > > They wouldn’t be able to reverse engineer exactly, as the engineering techniques are so far behind, but they could put a machine gun together with enough time and experimentation They had “machine guns” in the Civil War. They weren’t true machine guns (hence the quotes) but they did have hand cranked weapons like the Gatling Gun that you mentioned, as well as a handful of lesser known weapons like the Agar Gun, and a few other oddballs that weren’t hand cranked. There were two major issues, though. The first issue is that brass was difficult to make, and making enough cartridges to feed a machine gun was extremely difficult and extremely expensive. Cartridge weapons really took off after the Civil War due to advances in brass production that occurred in the 1870s. Without the ability to produce cheap brass cartridges, machine guns were too expensive to operate. There were a few weapons with a high rate of fire that were shown to Abraham Lincoln, and while the President was very impressed with them, the Army turned them down and refused to adopt them because they knew it would be too much of a logistical strain to field any of them. The second issue, which is somewhat related to the first, is that they didn’t know how to use machine guns. Because ammunition was so expensive, they didn’t use them on the battlefield. Instead, they used them to guard choke points like bridges and passes, where their high rate of fire could be maximized against the enemy. As such, the few “machine gun” type weapons that were fielded saw very little real use during the Civil War and overall didn’t have much of an effect on the battlefield. When they finally stared using the Maxim Gun on the battlefield, it changed the nature of war dramatically, ushering in the era of trench warfare. It’s not enough to teach them how to make a machine gun. You have to teach your Civil War era ammunition producers how to make cheap brass if you want the weapon to be practical. Otherwise your machine gun is just an extremely expensive weapon that they can’t afford to field in any significant numbers. And if you do somehow teach them to make cheap brass, you also have to convince them that the weapon is actually a game changer on the battlefield and shouldn’t just be used defensively at choke points. > [@LSLGuy](#): > > What prevented a lot of progress in firearms was the inability to manufacture dimensionally repeatable parts. This was a big issue, even during the Civil War. During the 1840s and 1850s they had been continually advancing the ability to manufacture interchangeable parts. But while most Civil War muskets were produced with parts that were supposedly interchangeable, if you look at actual surviving weapons from that era they were still doing a lot of hand fitting and fiddling to get all of the parts to work. So even through parts were supposed to be interchangeable, they often weren’t. In the 1400s they were still using matchlocks. The flintlock hadn’t even been invented yet. Wild West era rifles would seem like magic to them. ---
**Author:** ![Icerigger](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/icerigger/32/432_2.png) [@Icerigger](https://boards.straightdope.com/u/Icerigger)\ **Post date:** [February 9, 2025, 7:38pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/22 "2025-02-09T19:38:10Z")
Speaking of Harry Turtledove. In his Guns of the South a large part of the story has the confederates trying to replicate ammunition of the AK-47 in the 1860’s. ---
**Author:** ![LurkMeister](https://avatars.discourse-cdn.com/v4/letter/l/3da27b/32.png) [@LurkMeister](https://boards.straightdope.com/u/LurkMeister)\ **Post date:** [February 9, 2025, 10:16pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/23 "2025-02-09T22:16:34Z")
> [@Der\_Trihs](#): > > Electronics and such though, that’s another matter. I recall an old article from 1960s (I think) Analog magazine about a then-modern ramjet drone somehow ending up in the 1920s, and how it would be largely incomprehensible because they didn’t have either the theoretical knowledge or the instruments to understand what they are looking at. The examples that stuck in my mind where how without the theory behind them wave guides look just like empty spaces and a ramjet looks like a tube with a fuel line emptying into it. Weirdly enough, I thought of what I believe is the same article when I was reading the OP. I remember one of the other things discussed was the 1920s engineers trying to identify the metal used to construct it. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 9, 2025, 10:50pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/24 "2025-02-09T22:50:05Z")
> [@Der\_Trihs](#): > > Electronics and such though, that’s another matter. I recall an old article from 1960s (I think) Analog magazine about a then-modern ramjet drone somehow ending up in the 1920s, and how it would be largely incomprehensible because they didn’t have either the theoretical knowledge or the instruments to understand what they are looking at. The examples that stuck in my mind where how without the theory behind them wave guides look just like empty spaces and a ramjet looks like a tube with a fuel line emptying into it. John W. Campbell’s editorial “No Copying Allowed” (I think) - from 1948 ---
**Author:** ![Horatius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/horatius/32/3572_2.png) [@Horatius](https://boards.straightdope.com/u/Horatius)\ **Post date:** [February 10, 2025, 2:03pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/25 "2025-02-10T14:03:14Z")
> [@griffin1977](#): > > So I’m gonna change my estimate here, having thought about it. I recon it you give a modern assault rifle to a smart civil war era gunsmith, who’s familiar with Gattling Guns, they would work out a lot of how it works. This is almost the premise of [A Rebel in Time](https://en.wikipedia.org/wiki/A_Rebel_in_Time), by Harry Harrison. A guy goes back to just before the US Civil War, because he wants to help the south win. He doesn’t bring an assault rifle, though, he brings a WWII era Sten Gun. The Sten Gun was intended to be very simple, so that it could be manufactured in bulk without a lot of specialized equipment. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 10, 2025, 2:44pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/26 "2025-02-10T14:44:29Z")
Yep. A recoil action is vastly more approachable than a gas-operated one. Which brings up a larger point. If you want to boost somebodies’ tech, don’t bring them something magically advanced. Bring them something just barely out of their current reach. And even then, the knowledge of how to make the thing and make its materials is probably more valuable than knowledge of the existence or design of the thing itself. We are far enough past flint-knapping now that most of the secret sauce of 2025 [whatever] isn’t in the thing. It’s in the vast supply tree (not chain; the fan-out is enormous) of prerequisite tools and materials. ---
**Author:** ![DorkVader](https://avatars.discourse-cdn.com/v4/letter/d/73ab20/32.png) [@DorkVader](https://boards.straightdope.com/u/DorkVader)\ **Post date:** [February 12, 2025, 1:55am UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/27 "2025-02-12T01:55:35Z")
I wonder how far back you could take the metal can and can opener. It isn’t a gun, but can be considered vital military technology, I think. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [February 12, 2025, 2:07am UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/28 "2025-02-12T02:07:52Z")
Canned food was invented 50-some years before the can-opener, so a time-transferred can-opener would be a great help to folks ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [February 12, 2025, 9:29am UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/29 "2025-02-12T09:29:15Z")
If we aren’t restricted only to modern technology, an example that comes up in fiction is stirrups. Simple enough that they could be made by even a Stone Age society (they just need to know leather-working), but greatly increases the effectiveness of mounted warriors. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [February 12, 2025, 4:06pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/30 "2025-02-12T16:06:16Z")
> [@Der\_Trihs](#): > > stirrups > **[Amazon.com: Cato's Cavalry eBook : Jones, Marc, Jones, Kathleen : Kindle Store](https://www.amazon.com/Catos-Cavalry-Marc-Jones-ebook/dp/B00DHUOETS)** > > Amazon.com: Cato's Cavalry eBook : Jones, Marc, Jones, Kathleen : Kindle Store A real game changer. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [February 12, 2025, 7:36pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/31 "2025-02-12T19:36:59Z")
> [@Andy\_L](#): > > Canned food was invented 50-some years before the can-opener, so a time-transferred can-opener would be a great help to folks Modern can-openers are designed to open modern cans with modern ends. They are definitely designed to work together to a common standard. Heck, even church keys require a certain type of can edge so their fulcrum is able to get purchase & deliver leverage. What sort of ends were common in those early cans? Or where they all different? I’m young enough to remember when cans did not need openers; they each came with a key soldered onto the bottom and a peel off seam that fit the key. I’m sure early cans were not that sophisticated. But my point is that modern can openers are sorta an interim tech between different generations of self-opening cans. ---
**Author:** ![Elmer\_J.Fudd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/elmer_j.fudd/32/1211_2.png) [@Elmer\_J.Fudd](https://boards.straightdope.com/u/Elmer_J.Fudd)\ **Post date:** [February 12, 2025, 10:08pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/32 "2025-02-12T22:08:41Z")
How much extra value is a can opener over a bayonet. Sure, one might be easier, but they both get the job done. ---
**Author:** ![ThisOneGuy](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@ThisOneGuy](https://boards.straightdope.com/u/ThisOneGuy)\ **Post date:** [February 12, 2025, 11:30pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/33 "2025-02-12T23:30:51Z")
> [@LSLGuy](#): > > If you want to boost somebodies’ tech, don’t bring them something magically advanced. Bring them something just barely out of their current reach. > > And even then, the knowledge of how to make the thing and make its materials is probably more valuable than knowledge of the existence or design of the thing itself. This is the key. A matchlock gunsmith could easily copy a flintlock, somebody making plug bayonets would understand the value of a socket model and be able to make one. For interchangeable parts the secret sauce is more in the machine tools to make them than in the parts themselves. Same for the deep drawn brass cartridges. Showing up in say 1600 with a [pedal lathe](https://www.lathes.co.uk/barnes/) and a [hand cranked shaper](https://www.lathes.co.uk/adeptshaper/) and the knowledge to run them could do more to build up a country’s weapons industry than just showing them a finished gun. ---
**Author:** ![Horatius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/horatius/32/3572_2.png) [@Horatius](https://boards.straightdope.com/u/Horatius)\ **Post date:** [February 13, 2025, 8:07pm UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/34 "2025-02-13T20:07:26Z")
> [@Der\_Trihs](#): > > Simple enough that they could be made by even a Stone Age society (they just need to know leather-working), but greatly increases the effectiveness of mounted warriors. I recently read a novel about one of these “go back to Rome and teach them everything” stories. They made a point about Type 1 and Type 2 inventions. Type 1 were where just the idea was enough. The locals could immediately see the point, and know how to replicate it with their own skills and equipment. Type 2 were where there was some key enabling technology that they lacked, like metallurgy or the like. ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [February 14, 2025, 12:33am UTC](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080/35 "2025-02-14T00:33:04Z")
> [@LSLGuy](#): > > If you want to boost somebodies’ tech, don’t bring them something magically advanced. Bring them something just barely out of their current reach. Yeah. I laughed at this [tech boosting scene in the MCU movie _Eternals_](https://www.youtube.com/watch?v=uMcRulbS8F4). A real head-scratcher, one of many in that film that made me dislike it. [Previous page](https://boards.straightdope.com/t/when-is-the-earliest-date-military-technology-transfer-by-time-travel-should-work/1014080.md?page=1)