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Thread: Modify a Proto PM5 UL Ultralite frame to fit an automag

  1. #1

    Modify a Proto PM5 UL Ultralite frame to fit an automag

    This is a repost of content that has disappeared off the site in the last couple years, with a few tweaks from my own experience. Credit due to the original poster wherever you are! He had a nice marker shown in post and expressed that this was a really simple mod. I had to play around with the trigger/sear situation more than he did but it was a joy to shoot once all dialed in!

    1) PROTO UL Frame off a PM5. Note this is frame flat top, and shorter overall length than the Dye DM5. Only a PM5 UL will work with a short rail
    2) Dremel w/ thin cutting wheels and 3/16" grinding cylinder bit
    3) replacement bolt for your (rear) thumb screw as the head is too large. Alternatively you could take some meat off the frame to make the thumb screw work. I use a Tippmann style screw
    NOTE: This frame pictured is after I've already done the mod, but it's basically what you see when you take the grips off the first time...
    PICTURE x2

    STEP 1: Remove Trigger from frame and cut off the back half of the trigger - cut it anywhere so that there isn't any "vertical flange" protruding down that will get in the way of the trigger pin/rod (you don't need it any more because it's no longer going to be an Electronic frame. Note this cut will leave the pin "hanging loose". I've also experimented successfully with leaving the tab on and hogging out the grub screw hole to utilize as a "pin guide". More delicate to get lined up, and smoothed out so nothing catches - but it can be done
    ALSO SEE TUNING STEP 2, in case you want to make that cut now. Might be better to wait....

    STEP 2: Cut off the little square "flange" that sticks out into the inside of the frame on the left side of the frame... if you don't remove this flange it will get in the way of the trigger pin/rod. The flange was the trigger return spring stop. Frame is now arguably no longer usable as a stock PM5 frame, it's the point of no return. Technically still possible to use but you'd only have a microswitch for trigger return

    STEP 3: Cut approx. 1/2in off the trigger sear rod - NOTE: I had to "extend" the trigger rod after removing this .505in of the pin, so .45in might be a "better" length... either way you can "extend" or "retract" as necessary; .5in will get you in the ball park

    STEP 4: Elongate the front mounting hole w/ the 3/16" grinding bit by 2mm TOWARD THE BACK of the frame; the center of the frame mounting holes are only 2mm further apart than the stock Automag holes. Go slow and recheck often, doesn't take much.
    PICTURE x2

    STEP 5: "Fill" the hole in the trigger w/ your choice of "filler"... I used Metal epoxy, recommend JB WELD. Just needs to be something to hold back the sear pin when it's gassed up. Depending on how you want your sear to "sit", you might want the hole recessed a bit or filled flush.

    STEP 6: Reassemble the marker w/ your new trigger frame once the trigger hole "filler" is set, and gas it up... NOW BEGIN "TUNING"

    STEP 7: TUNING - There are two things that you will have to do to tune this set up:
    1. Extend/Retract the trigger sear rod (the one you cut in step3) as necessary so that when gassed up it is <1/8 loose, to just up against, the trigger -and-
    2. Notch the top of the trigger as necessary in order to use the "forward travel stop" pin... without notching the top of the trigger, you will not be able to use this pin and the trigger will have freedom of movement forward. Once this has been notched deep enough, the pin can be used and moved in/out as normal to get the sear pin to seat fully against the top (ABOVE THE "HUMP" IN THE "DIMPLE" left behind from the old "HOLE" in the trigger) and the trigger will not have ANY freedom of movement when gassed up.

    • I added a picture of my final result, the one with the blue CF ULE frame for an example of alternate trigger handling.
    • You can use this PM5 frame on a short rail with just a smidgen of grinding off the nose - an angled VASA is best. I took off less than 1/8 at deepest angle of cut using a belt sander then finished out by hand. I touched up with a black oxide chemical solution, it looks great.
    • Sorry pics are jacked up - will try to fix that
    Attached Images Attached Images           
    Last edited by Mueller; 09-14-2018 at 10:29 AM.

  2. #2
    this would be good to archive for the home gamers.
    if the powers that be deem so.
    good kicking off point for people."You play stupid games, you get stupid prizes." RU

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