Runout caused by receiver

Discussion in 'Reloading' started by tlk, Apr 18, 2009.

  1. tlk

    tlk Well-Known Member

    Apr 11, 2008
    Question: when I load a round into the chamber the bullet tip is contacting the receiver as it leaves the magazine. This is with factory loads. Will this cause any runout on its own?

  2. nheninge

    nheninge Well-Known Member

    Oct 20, 2008
    Does it deform the tip? Soft nosed lead tips that have been deformed may change the BC of your bullet, thus altering the trajectory. I have even seen polymer tips deformed in this manner and accuracy may be impaired.

    Runout is easy enough to measure. Chamber a round and then eject it slowly, minimizing contact. Compare pre chambering vs. post chambering runout values to see if it changes

  3. boomtube

    boomtube Well-Known Member

    Oct 8, 2007
    I can't say if your concentricity if being harmed by your ammo making normal feeding contact in your rifle but I doubt it.

    I can tell you that, technically, the point you are addressing is a part of the action that's called the "feed ramp", not the receiver.
  4. woods

    woods Well-Known Member

    Jun 4, 2006
    I tried to make it happen once when someone mentioned it on a post. Could not verifiably induce runout by chambering a loaded case. I would suspect if it were possible then it would depend upon several variables all being wrong at the same time. Some of those would be the force necessary to break the case out of the magazine retainers, angle of the ramp, how the case head is picked up by the bolt face, etc.

    It would seem to me that the most important factor in inducing runout would be the softness of the brass in your neck. I use a Bersin Tool


    to straighten runout and it is possible to see how much force is necessary to push the bullet with the tool. With new brass I noticed that it takes so little force to move the neck to one side or the other that you can do it with your thumb. When the brass is soft like that, it is harder to reduce runout because it takes so little force to move the neck that you wind up moving the runout from side to side. After 3 or 4 firing when the brass becomes harder it becomes harder to move the bullet in the neck but much easier to significantly improve runout.

    So I would think that new brass or recently annealed brass would exhibit a problem of induced runout by chambering much easier than a severaly times fired case.