Renovating Dad's L579 as if by the 3 Stooges

Discussion in 'Sako Medium Actions' started by BruceHB, Jul 19, 2021.

  1. BruceHB

    BruceHB Well-Known Member

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    Continuing work on my dad’s Sako bolt action rifle, I got out to the rifle range today to finish the barrel break-in shooting factory Hornady 108 gr ELD Match cartridges for brass. Having to replace my father’s Sako OEM scope mounts after damaging them the morning started much like a 3 Stooges skit. With a very innovative design I had a slow start getting the scope aligned on target then realizing I was almost out of reticle adjustment requiring me to start over centering the adjusters mid-adjustment and using the scope mount base adjusters to get me on target.

    After some minor frustration I was getting closer but also growing impatient. Impatience and guns rarely work well together and when the scope and bases fell off the rifle because I forgot to tighten the screws after adjusting the base for windage I peered around hoping no one saw that. Then there was working with a very old scope operating differently than my new Nightforce Optics where I wasted another 30 minutes trying to figure out why everything was blurry after a simple parallax adjustment. It took 30 minutes to realize you have to lock the parallax adjustment ring after each adjustment, WTF, really?

    Haven’t shot for many months I forgot my LabRadar chronograph was set up for an air rifle and couldn’t get proper readings. Thinking this was going to be long or worse, useless day I placed a new target design up and realized the ½ inch red bull progressively became more difficult to see as you hit the red area. Realizing I need to be high anyway at 100 years I made the adjustment so I could see the red dot after 1 or 2 hits. I was shooting off my fathers dated front rest and with factory ammo was shooting about 1 MOA adding to my frustration. Compared to my Nightforce optics the scope looked like looking through a dirty window in low light.

    Hoping to stop the downward trend I switched out my fathers front rest to my new Armageddon shooting bag which turned out to be more stable. While contending with an old optic with limited power, I was able to get some ok five shoot groups shooting factory ammo. The group pictured here measures .39 center to center and had an extreme velocity deviation of 65 fps, horrible but normal for factory ammo.

    Shooing close to 125 rounds today I cleaned the gun three times while shooting, once with a copper removal agent too. I did slow fire letting the rifle cool between sets for at least 5 minutes.


    With load development and a better optic I’m hoping to improve the performance of my fathers Sako L579 which he and his friend Mas Iwamoto modified back in the day. All I’ve done is replace the Shilen 243 Ackley Improved barrel with a 26" Hawk Hill Match barrel with a custom 6mm Creedmoor chamber and APA Little Bastard muzzle brake. While my father’s rifle will never be a competitive PRS type rifle, I’m hoping to get it close in precision at least off a bench.

    Dad’s mods were a blue printed action, set in Devcon in the stock, the barrel free floated and the installation of a Canjar set trigger releasing at 2 lbs or 2 ounces.
     

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    Old Hippie likes this.

  2. Old Hippie

    Old Hippie Formerly known as bloorooster

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    Wow!
    Incredible shooting, even after all the Murphy’s Law episodes! Lol! I have days like that…at least you didn’t lock your keys up in the vehicle when you got to the range!

    Very nice rifle build!

    Old Hippie
     
  3. BruceHB

    BruceHB Well-Known Member

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    Post update

    I want to clarify my reference to shooting factory Hornady 108 gr ELD Match ammo to break in my barrel giving me once fired brass for load development. The 26" Hawk Hill barrel was chambered to non-SAAMI specs by Eric Anderson of Blue Mountain Precision (a known PRS competitor) with a slightly tighter neck (.275) and shorter freebore (.135) in a one in 7.5 twist rate.

    The significantly shorter freebore jams the factory Hornady 108 gr ELD Match ammo into the lands, so I measured the CBTO using various CBTO methods with the final check using Dykem Steel Blue on the bullets, chambering them into the chamber and checking for evidence the bullet was just touching the lands. I determined a CBTO of 2.180 was just off the lands. Reseating the factory Hornady 108 gr ELD Match ammo to this depth, I measured the CBTO again with “MY” comparator and found I had 3 groups of CBTO cartridges, the majority being 2.180 with very small groups of 2.179 and 2.178 CBTO which I used to get me on target and fouling shots.

    I noticed a small velocity increase towards the end of the day of approximately 35 to 40 fps. Extreme deviation for the day was 131 fps with the average SD being approximately 65 fps. While none of the groups are anything to brag about, the groups pictured here were towards the end of the day shooting reseated factory Hornady ammo shooting off an Armageddon bag (highly recommended) and unknown rear bag.

    These results suggest good potential for load development starting with ladder tests with Hodgdon H4350 and Vihtavuori N555 shooting Berger 105 grain Hybrid target and 103 gr Vapor Trail bullets using both production and handmade bullets from Tom Jacobs of Vapor Trail. Once an appropriate velocity node is found I’ll be sizing and seating using the dies from Short Action Custom dies and CCI BR-2 primers. I’ll spare all the case prep steps for another post.

    The target is three inches in diameter with a half inch red bulls eyes.
     

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