Grendel/Sako STR Questions

Discussion in 'General Sako Discussions' started by Dave Buffington, Nov 28, 2019.

  1. Dave Buffington

    Dave Buffington Active Member

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    Well, I finally tore down the Grendel and may have identified the source of the feeding problem:

    [​IMG]

    While the rest of the gun is quite well built and cleverly engineered, the follower spring seems like an afterthought. It doesn't support the front of the follower, allowing it to dip and dive and bind in the box. Any thoughts?

    Thanks!
    Dave

     

  2. CVCOBRA1

    CVCOBRA1 Well-Known Member

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    Do you know if that is even the correct follower spring? Looks like something somebody made up in their basement out of a cut up coffee can.
     
  3. icebear

    icebear Well-Known Member

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    Does that spring slot into the follower, or does it just rest on the bottom of the follower? Can you post a picture of the spring and follower assembly removed from the rifle? I am thinking that I have had more than one magazine feeding problem caused by a follower spring of that type being installed backwards, or upside down, or not properly slotted into the bottom of the follower. Without knowing exactly how the spring and follower interact, I can't go any further than that, but it's something to think about.
     
    FLT and CVCOBRA1 like this.
  4. Dave Buffington

    Dave Buffington Active Member

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    It actually looks worse than that in real life, and no, I have no idea if that was the original and/or correct follower or spring. As mentioned earlier in the thread, there are some small hints elsewhere on the internet that feed problems existed with this gun and that and upgraded follower and/or spring was available.

    Having said that, there is no obvious indication that this gun was taken apart before, and given the unique construction of the gun, it would be very easy to create visible damage if you weren't patient about taking it apart.

    Now, for Icebear, here are some photos of the spring and follower that came with the gun. First, the upper side of the follower:

    [​IMG]
    Now the underside:

    [​IMG]
    Now the spring. The tape, which I put there, indicates the top front edge of the spring:

    [​IMG]

    That does fit, a bit loosely, into the round and angled bits on the underside of the follower.

    Again, all thoughts, suggestions and ideas are welcome!

    Thanks!
    Dave
     
  5. icebear

    icebear Well-Known Member

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    The design of that spring should keep the follower level. If the follower is binding, I would examine the follower and the inside of the magazine box carefully for burrs or high spots that could bind, and carefully polish friction surfaces (without taking any significant amount of material off the follower). I've done several fixes like this on detachable magazines, especially those Godawful 40-round aftermarket Valmet mags and that sort of thing. It can take a very long time to sort out a follower that binds. Light lubrication can also help, making sure that the chosen lubricant is compatible with the plastic stock. Anhydrous graphite is absolutely safe on plastic, but messy. CLP should be safe as well, or Moly might be worth a try.
     
  6. Dave Buffington

    Dave Buffington Active Member

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    Thanks! Now that I have the follower out and can examine it closely, it appears that someone already tried taking some material off the sides of the follower. There are a variety of filing marks, all rough enough that they may have caused as many problems as they solved.

    So I'm going to try to clean it up without taking much at all off the sides, and I'll see if that makes an improvement.

    Thanks!
    Dave
     
  7. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

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    It just occurred to me that even if you had a factory A-II magazine follower that it wouldn't help address the problem because the entire magazine/box/spring/follower is a proprietary assembly which was substituted by Grendel for the factory assembly. Therefore, nothing in it is necessarily a match for the factory parts.

    It looks to me from the photos that Grendel's magazine spring should have "longer loops", that is, it should fill more of the box than it does in order to exert even upward pressure on the follower. Solving the problem may require you to invent something.
     

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