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Thread: Project: 10mm Auto Desert Eagle Attempt...

  1. #1

    Default Project: 10mm Auto Desert Eagle Attempt...

    (This was previously post on another forum, which might share some members, but not all, so I am re-posting it here as well.)

    Here we go... I will periodically update the progress of my first attempt at chambering a Desert Eagle in 10mm auto.

    So the .357 magnum barrels needed for this project finally came back into stock a few weeks ago, and I have acquired a couple of them for this project. This attempt will be based on the six inch barrel.

    The story so far...
    I was looking at a ballistics chart a while back and realized that a 10mm Auto round overlaps into the .357 magnum range pretty far, relative to pressure and energy. (higher SAAMI pressures actually) This established potential usage, in theory at least.

    First I got my .357 barrel running well with .357 mag, as performance out of the box for this barrel, was poor. This was a two part issue I believe... rough chamber, and sharp bolt. I polished in specific places on both... I used a lot of Dremel time in small amounts, and a lot of Dykem to achieve very good results with most any .357 magnum rounds above 1200fps. Also, extraction was excellent, so I was confident the headspacing was very good also.

    I don't own a 10mm auto, so I bought some of the higher loadings, which were Federal 180gr "Trophy Bonded" JSP's... a hunting round for 10mm Auto basically. These are 1275fps 180gr, for 650ft-lbs energy... that should be plenty to cycle a Desert Eagle slide... on or off paper. We shall see... "real world" often includes variable which we don't consider. Worst case, if the rounds have any issue cycling the slide, I can remove the inner springs, as these small short rounds won't need as much spring pressure as other rounds do, to close the slide. Also, I can make a custom gas piston with smaller vents, no vents at all, and/or a tighter fit, for less blow-by of gas. As I said... I believe I can make this work. It won't be simple, easy, or inexpensive, but that is the price for having something you want sometimes.

    Extraction: of great importance, because of the Desert Eagle not being blowback, was extraction... I just looked this up at first, and the rim diameter is so close to .357, only TINY modification to the extractor claw allows it to fully engage the rim... I am going to try it without this first, as I think it will still work. The rims are only around 14 thousandths (0.014) different in diameter.

    Feeding: So I modified a .41 magnum magazine a little and added a space filler to the back of the magazine (temporary for testing, as with almost everything at this point) and got the 10mm rounds to where I could feed them out of the magazine... I sketched up a simple filler that will pass through a hole/slot in a modified follower to keep the rounds forward to the correct position in the magazine for the bolt to get them. Then, by hand operation of the slide, with a sleeve I made to fit a 50ae chamber (which I headspaced with a dowel through the barrel) I was able to feed and extract 10mm rounds with the .357 extractor. I stopped here as there isn't much more I can do without making the barrel. I believe the probability is high that I can work out feeding bugs later... I just need a 10mm barrel to do much more relative to feeding.

    Barrel making methods: I looked into bore and rifle, and sleeving. Both have their advantages and disadvantages. Both are expensive. I have never done either. I am not a gunsmith, nor a great machinist... what I make, I make well, but I just don't have that much knowledge and experience. I am a general machinist. Most of my experience being at a factory, I know only specific procedures, and we do nothing of complexity, and with very specific tooling. I am buying all tooling for this project.
    So... I decided to get enough to try both methods. I got enough barrel sleeve to get two tries in case of issues Then I got a "gun drill" (bit) which is kind of a hybrid reamer/drill for precision which will be used to drill the barrel out to near 10mm for reaming, pre-rifling. I then obtained a rifling button for rifling after drill/ream polish process.
    OR, I can also drill the barrel out dramatically, to fit the Barrel Sleeve.

    Keeping the gas port clear during this is going to take effort... I am thinking I might make an adapter that forces oil through the gas port backwards during drilling to keep it clear and add lubrication... can't hurt.

    If I drill/ream/rifle, all I have to do is keep the debris from the gas port. (might wax plug it also)
    If I bore/sleeve, all I have to do is drill the gas port in the sleeve at exactly the right spot... pretty challenging, but I can do it.

    So that is where I am as of today... in the next few weeks, maybe months, I will come back and state progress and success with each stage. Even if I am not successful, this documentation might be something someone else can reference and work off of to make it successful.

    One of the main reasons I think this round was never considered for a Desert Eagle is reliable cycling of the slide... if you look at the weakest native Desert Eagle round, the .357 Magnum, 90% of factory loadings on the shelf will work. If you look at 10mm Auto, it is probably almost inverse of that... 90% of factory loadings simply would not cycle the slide of a Desert Eagle in my opinion. Most 10mm factory ammo is loaded WAY below SAAMI pressure maximum for some reason.

    I just want a 10mm Desert Eagle, so I am going to try this. If I hit a wall I didn't see, I will get some stitches and report back here.


  2. #2
    Join Date
    Nov 2017


    Very cool!

    Some might argue it's just an expensive way to re-make the .41 Desert Eagle. But I tend to think a cool project is all the justification you need.

    Let us know how it progresses!

  3. #3
    Join Date
    Nov 2017


    Another approach: according to the video in , MRI subs out barrel manufacture to Pequot Tool & Manufacturing. I wonder if they would be willing to sell you a barrel with the bore unfinished. Assuming they did everything else, including drilling the gas tube, you would then just have to bore the barrel to the correct diameter, then have it rifled and chamber reamed.

    It might be worth asking about, anyway.

  4. #4


    Thank you for the information. If this doesn't go well, I will consider that for my next approach. I now have all tooling and the project is loaded, hammer cocked and safety off... just need some time to pull the trigger.

    I am excited about this project for sure, but there seems to be a multitude of less exciting projects that require my attention first.


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