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Discussion Starter · #1 · (Edited)
The Geissele Hi-Speed straight from the factory has a large housing covering the rear of the disconnector where there is an adjustment screw. That housing is on the tail of the trigger, just forward of where the shaft of the safety/selector on an AR would sit. I don't know the exact diameters, but the ACR safety is much fatter, maybe the difference between .4' and .7'. Because the housing is far to the rear, the difference is enough to cause interference, and the ACR safety cannot be reinstalled if the Hi-Speed is in place. That is, not without modification.

The Hi-Speed is known for an extremely clean, crisp, and light break, and one of the shortest resets available. An ACR equipped with this trigger makes a great candidate for long range accuracy work, 3-Gun competitions, and any other matches in which trigger weight is not regulated. I believe this is also the only adjustable Geissele trigger.

Below are images detailing the modifications I made to make installation of this trigger possible in the ACR.

IMG_1537.jpg IMG_1538.jpg IMG_1539.jpg

These pictures show how I (using a Dremel, on my back porch) ground enough room for the fat ACR safety to clear the disconnector housing. It may look as though I ground a bit off the horizontal surface of the trigger tail, but that is just a bit of the finish being scuffed and removed by my clumsiness.

More to come.
 

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Discussion Starter · #2 · (Edited)
IMG_1536.jpg IMG_1540.jpg IMG_1541.jpg

These show how the rear of the disconnector must be ground to fit flush with the rear of the (now receded) housing.

Fairly simple.

As I was grinding, I periodically installed the trigger in the trigger-box without the springs, and attempted to install the safety. If done gradually, you should have a fully functioning trigger before any material that affects function has been removed.
 

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Discussion Starter · #3 · (Edited)
Once the safety can be installed, locking the trigger-box in the lower, you have done enough work on the trigger itself. This does not mean, however, that the trigger will be fully functional yet. I found the the notch in the shaft of the safety, that allows the movement of the trigger tail while on 'FIRE', is not wide enough for the tail of the Hi-speed. So I took my handy dandy Dremel and widened the gap. The trigger should now be fully functioning. You could take it to the range, do whatever.

BUT. If you are like me, you are experiencing some over-travel, which manifests itself as a long reset. Too long. Unacceptable for a trigger of this quality and refinement.

I just ignored it for a week or two, but eventually I found it obnoxious enough to fix. I mixed up some JB Weld and slathered a bit on the gap on the safety shaft, the same one that I widened. It was still soft enough to level itself as it dried, so it left a flat, smooth shelf. I was prepared to sand the excess of (if the trigger could not travel enough) or add another layer of JB (if it still traveled too much), but when I popped it in the next day, It was perfect. The trigger now has the light, crisp, smooth operation that it is supposed to. The following pictures show the safety in its current state; widened and with the JB Weld blob.

IMG_1533.jpg IMG_1534.jpg IMG_1535.jpg
 

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Discussion Starter · #4 ·
The trigger should now be fully functioning, with the same performance that it was manufactured with. One of the beautiful things about this mod is that if you're careful, the trigger can still be installed and retain full functionality in any other rifle or platform. If put in an AR it will behave just as well as one straight from the factory. I may end up picking up a super ACR or SSA someday, but I doubt either will replace this one. Here are some some shots of the assembled trigger assembly and parts:

IMG_1530.jpg IMG_1531.jpg IMG_1532.jpg IMG_1542.jpg IMG_1543.jpg

Thats all she wrote folks. If this helps anyone pull off the same mod, great! If not, whatever, I have a Hi-Speed in my ACR and you don't :p

FIN!
 

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sweet bro.... nice work....

thanks for the huge and accurate writeup... Pics help greatly....

its no wonder that Bill Giessele didn't want to deal with or mess with the silly goofy safety that the ACR has... Just not enough of them out there to make it pay off like standard AR's... I'm thrilled with the SD-E, but for those that want to run n gun - this might be the game changer....
 

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I got my lower from a friend and never thought to check it. If I recall it's a light crisp 1 stage.

The 2 stages I've felt on 416's here feel glorious though. Definitely tempting.
 
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