Got my M40 back today

Discussion in 'Maintenance / Tweaks / Technical Difficulties / So' started by RiceCakes, Sep 1, 2006.

  1. RiceCakes

    RiceCakes Guest

    287
    0
    0
    From SAI. Went in for a trigger reduction from 8+. I had already polished the firing pin parts real well, so it was pretty smooth already. They put in a new trigger bar. When I got it back, it was probably at 7. (I have weights for 6, and 8, but no 7). I went back through the trigger tune up, bent spring 13 to 90 deg. back up to 7.5-8. I looked at the trigger a little more, bent 13 to 180 deg., wham, right at 6. This spring actually counters the firing pin (from what I can tell), and I think a heavier spring there, or a more obtuse angle (past 180) will help lighten the load a little. What do the experts think? Maybe mine is just weird!
    The one potential problem I see is if it gets too heavy, it could preload past 72%.

    Oh btw, I am not a gunsmith by any means so only try what I did if you don't hold me liable. /disclaimer
     
  2. Guest

    Guest Guest

    How quick was the turnaround?

    Did you just send it in with the complaint of the trigger being too heavy and they said they'd give it a look?
     

  3. RiceCakes

    RiceCakes Guest

    287
    0
    0
    Yeah. I said my trigger was 8+. It has to go to Georgia. I sent it ground (UPS stores will tell you 2nd day air only, I boxed it and sent it ground myself, SAI said that it was legal). I think they had it for 2 days before it shipped back. So ups shipping time to and back from Georgia plus 2 days. They send it UPS back to your place (no FFL required).
     
  4. bigtaco

    bigtaco Active Member

    1,791
    10
    38
    ricecakes, i can only trust that the result you achieved is true.

    but, the post is dogged against pin #14. if you remove pin #14, the post will push the sear all the way to the rear of the channel, completely overcoing the fp spring.

    the firing pin must fall off of the post. by making the spring which holds the post up lighter, you make it easier for the sear to fall. that is the premise behind lessening the included angle of the spring, and was told to me by the old steyr repair gunsmith.

    i am now FORCED to experiment with bending the spring the other way. (guess i better get some spares). it will be interesting to see what happens.

    thanks for posting up about experimentation!!!

    my initial thougth is that by bending the spring to 90, i have increased the rate of the spring but decreased the preload.

    by bending it to 180, you have decreased the spring rate but increased the preload.

    that spring would not be hard to bend up yourself if you had a lathe, a clamp and some wire. might be neat to experiment with WAY different spring rates and preloads.
     
  5. RiceCakes

    RiceCakes Guest

    287
    0
    0
    I tried a little bit. I bent it back to 120, then reversed the spring (facing the wrong way). The problem I saw there was that the sear would not reset. I dont think it changes the number of pounds, but it may give it a slightly smaller stroke. Of course, it may also take it past 72%. Cant say for sure. But it feels better, and I shoot better with it like that, so damn the consequences!!!! :D
     
  6. Wulf

    Wulf Premium Member

    1,664
    4
    0
    Hiya *Cakes :)

    What are the consequences?..."'splain it to me, Lucy!". I'm all for a lighter trigger pull and quicker reset action...within reason. BT?...Whataya think the pos and neg consequences could be?

    Wulf
     
  7. RiceCakes

    RiceCakes Guest

    287
    0
    0
    BT can jump in anytime, he seems to know muh more about the inner workings. The only thing I can think of is that it will/could increase the preload, past 72%, effectively making it an unsafe DA. I dont know, I have no way of testing this. But there is the one major con I can think of.
     
  8. bigtaco

    bigtaco Active Member

    1,791
    10
    38
    i still say that the post dogs against pin 14. if you had a 1000 ton spring rate, you'd get 1000 tons right into pin 14. the sear isn't going any farther back unless something else pushes it back like,... the trigger bar.

    if you had a .001 pound spring rate, it wouldn't push the post back at all and the firing pin spring would actually push the sear and the post forward thereby lessening the preload on the firing pin.

    try it. take your gun apart. push the post forward and remove pin 14. you'll see the post push the sear all the way back in it's groove.