Know that It’s not possible to exceed 4,5 joules without using a long barrel. That’s the maximum I was able to achieve with the original barrel
after modifying everything on the magazine. The data and a video are available in the first post
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Umarex [UMAREX] Glock 17 Gen 5 Tuning : Power Upgrade – Almost 7 Joules!
- Thread starter Clark33
- Start date
Know that It’s not possible to exceed 4,5 joules without using a long barrel. That’s the maximum I was able to achieve with the original barrel
after modifying everything on the magazine. The data and a video are available in the first post
On the pellet version, you can remove the slide very easily you just need to push out the front pin, pull the slide back, then lift it up and it comes off. You can do that in less than 20sec. To change the barrel however, you'll also need to push out the rear pin to remove the entire internal mechanism : barrel, trigger, and hammer, which are all held in place in the plastic frame. It might seem intimidating at first, but I was surprised by how simple the mechanism is, there are actually very few parts. A hammer, sear, trigger bar and a trigger that has the rotating finger attached directly to it, which rotates the magazine chain https://streamable.com/uu1t35
Inside the slide, the blowback system is screwed in and contains a seal and the firing pin in the center. I find it very well-designed and clever, despite Umarex usual and unfortunate use of zamak and other alloys. Still, it seems reliable and durable overall. It’s a really cool Glock to modify. Another advantage is that it works in both single and double action, meaning you can disable the blowback and still shoot without having to manually rack the slide after each shot. In theory, that could increase power slightly, but I haven’t really tested it myself as I’m not interested in that.
Be careful though, its not a drilling job but a sculpting job, if you're not handy or don't have the right tools :i recommand a flex shaft grinder with a foot pedal, 1mm to 1.25mm carbide corn end mill for the valve and 6mm ball end mill for the magasine head. You’ll need to be precise when working on the valve which is tiny and in steel, or the head of the magazine. It’s easy to break something or remove too much material and pass through by mistake. Since spare parts aren’t available, you'd have to buy a new magazine.
But if you're into tinkering, it's a lot of fun. I don't have the BB version, but it’s obvious the pellet version is far more accurate. With my long barrel, it's very precise. It also has the benefit of holding more shots, and you can use specialty pellets like the H&N Hornet pistol with brass pointed tips for plinking.
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The pellet version is really a completely different gun. The BB version is excellent if what you're looking for is a training pistol that operates and feels almost identical to the real thing, it will never be very powerful or accurate however. The pellet version on the other hand is really more like a double action revolver that uses a belt instead of a cylinder. It's got more potential for accuracy and power, but the trigger is awful.
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Hello Clark33, I am glad for the info you shared I also like the same approach you have to having the pellet version reach its potential even less shot count but more Joules and accuracy. I do like to tinker also and have decent skills, like you mentioned (i have flex shaft and grinders also some machining skills). I would like to ask if you could give us a picture or dimension description of the enlarging of the cavity on the magazine so I have a guide on how to do this if you can share that would be great. The rest of the mods looks like you covered... later on Id like to do the longer barrel length either thread the end or press fit adapter 7/16 to 1/2-20 for moderator.
Just wanted to get an idea of how much material to remove from the gas chamber to enlarge it any guidance is appreciated. I did the same mod on a crossman 2240 opened up the chamber by about 20 then 30%, after 30% it did not make any difference also enlarged the all gas pass thru holes and with 16" barrel it is shooting reliably around 600fps. Any advice on the chamber would be great
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