L579 243 Win info required

Discussion in 'Sako Medium Actions' started by Roeltru, Nov 6, 2013.

  1. Roeltru

    Roeltru Member

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    Hi guys,


    I'm new here, awesome site! I am from South Africa and have 2 Sako's. A M85 in 30-06Spr which shoots 0.5MOA if I do my bit and a L579 in 243Win, which is causing me some troubles. The L579 I inherited from my grandfather who passed away when I was 7. The rifle serial number is 349XX (5 digit number)

    I have 2 questions, if you guys can please assist me.

    1. When was the rifle manufactured (from the reference section, it seems around 1964?) ?

    2. What is the rate of twist for the barrel (I can't get a decent measurement using a cleaning rod and patch)?

    I see general consensus on the site is that it should be 1 in 10, but I don't know if Sako ever deviated from this. I can't get decent groupings with Nosler Ballistic Tip 95gr bullets (the only bullet I can get in bulk at a decent price in South Africa).

    Thanks for the great site!

    Roeltru

    Ps. Sorry for the semi disjointed post, it's a bit about me and my rifles and my problem child rifle! :)
     

  2. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

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    The early to mid 1960's would be a reasonable guess on your rifle's date of manufacture. The L579, introduced in 1959, started numbering approximately where the L57's left off in the mid-10,000's, so yours would be 20,000 or so into the run.

    Sako made some barrels for the .244 Remington on which the twist was about 1-11.25" (or the near metric equivalent). It is certainly possible that your gun has a barrel intended for a .244, but which got a .243 chamber instead. The only way to know for sure is to retry the cleaning rod trick. I find that pulling the rod through rather than pushing it usually gets you a more accurate read. Try this: Insert your rod from the muzzle. Place a tight-fitting patch on the end now sticking out in the loading port. Withdraw it until it is a few inches into the barrel and seems to be turning with the rifling. Now place a piece of masking tape around the rod even with the muzzle. Place an index mark on the tape. Withdraw the rod from the muzzle end until the index mark on the tape has made exactly one revolution. Measure the distance from the muzzle to the bottom of the tape. Repeat a couple of times and average your measurements. This should get you about as close as possible without more sophisticated instrumentation.

    If your rifle does have the ".244" barrel, then the 95 Ballistic Tip is right on the edge of stability. I have used 90 grain Ballistic Tips in a .244 Sako successfully, however, so the small difference in length might make a bigger difference in stability. So, if this is your problem and if you can get the 90 grainers you might be able to improve things with them (and they'll do whatever the 95's will do).

    However, before blaming the rifling twist (which isn't likely your problem), look at some other factors. If your action screws are not properly tightened it can cause bullets to walk all over the target. I like to tighten the front action screw as tight as practical, then follow that with tightening the rear screw just snug. I found my own Sako .243, which had been a very tight shooter, wandering around in puzzling manner when I went to check the zero on it after having let it sit unused in the safe for several years. I was greatly distressed until I thought to check the action screws, which turned out to be rather loose (wood tends to shrink over the years). After cinching them down properly it went back to shooting nice, neat groups just like it had before.
     
    Last edited: Nov 6, 2013
  3. Roeltru

    Roeltru Member

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    Thanks stonecreek. Will try the reverse method to measure twist! The main problem is I don't know what the twist is, so I have no idea what weight bullets I actually need to use! :oops:
     
  4. Roeltru

    Roeltru Member

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    A quick clean with Hoppe's #9 and the measurement was easy. Definitely 1 in 10! The quest continues!
     
  5. misako50

    misako50 Sako-addicted

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    Roeltru- By any chance did the bullets make oblong holes in your targets? The reason I ask this is due to an experience I had with some 105 Gr .243 cal. bullets. I noticed on a very calm evening that they seemed to be making a very strange noise in flight and were not terribly accurate. When I took them out to the range again, I noticed the oblong holes and not round, as they should be. I tried backing off the load to slow it down and that helped but it still wasn't what I had in mind. Dropped the bullets and went to lighter noslers and that did the trick.-Misako
     
  6. terenceh

    terenceh Member

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    I had exactly the same (key-holing?) problem when I tried 105 Gr bullets in my mid-1960s "Bofors" Sako Forester in 0.243 Winchester (1 in 10 twist), yet it handles 100 GR perfectly.
     
  7. misako50

    misako50 Sako-addicted

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    Terenceh- We must both be suffering a terrible sensitivity to recoil?:nod2: Seriously, what name brand bullets are the 100s that you use.?----Misako
     
  8. terenceh

    terenceh Member

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    Hi Misako,

    The current 100s are Hornady, but I tend to use 70 GR SMKs or 85 GR Sierra SPs, as these seem to suit the Forester better (and my shoulder|). The 105s which appeared to key hole were Speer SPs (a partial box, given me by someone, and they appeared to have been pulled. I soon found out why!)....Terenceh
     
  9. misako50

    misako50 Sako-addicted

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    My 105s were speers also . I like to use Nozzies as much as possible but they aren't in stock at times due to whatever drives the "machine".-Misako
     
  10. terenceh

    terenceh Member

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    Noslers aren't as readily available as Sierra and Hornady over here, but I once bought some 100 Gr Nosler Partitions from a gun shop in Glenrock, Wyoming (the only ones he stocked in 6 mm back then). They worked fine in the Forester, but apart from being relatively expensive, they were really "over constructed" for my particular needs at the time..........Terenceh.
     
  11. Roeltru

    Roeltru Member

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    Hi guys,

    Misako, no I don't get key holes. I'm starting to think maybe the rifle simply doesn't like the 95gr Ballistic Tips.

    I'm going to try some 87gr Vmax in the next few weeks. Unfortunately the handle on my Lee Auto Prime broke when I was loading on Tuesday and getting replacements is near impossible here in South Africa. I want to convert the unit with a drill and tap so I can screw it into my press and then use my press to prime.
     
  12. misako50

    misako50 Sako-addicted

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    The bullets I have had the best luck with, for accuracy in a .243, are "Bergers" but I like to use stouter bullets for deer and antelope. I will try to find some 90s or 100s that my 1 in 10s like but I don't have enough time this year to try many of them before I settle on one for a deer load.-Misako
     

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