Sako AV 300 Win Mag barrel questions

Discussion in 'Sako Long/Magnum Actions' started by Sakogun, Oct 17, 2014.

  1. Sakogun

    Sakogun Active Member

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    I have a few questions:
    1. On the crown, when did Sako start applying what looks like an 11 degree taper from OD of barrel to the first chamfer entering the bore?

    2. What's the typical maximum number of ID threads left showing in the receiver when the barrel is screwed in from the factory?

    3. What are the normal barrel markings on an AV 300 Win Mag?


    I ask because I bought a AV 300 win mag a few months ago and the rifle is beautiful including the rifling. Last night I started to work up a few loads so I can take it out and shoot it for the first time this weekend. When I located the lands using my hornady gauge I noticed the lands are 3.495" from the bottom of the case when using a 180 gr sierra bullet. Many of the reloading manuals indicate a max COAL of 3.340" which puts the lands 0.155" further out. I normally like to start loading 30-40 thousandths back from the lands, but for this rifle it would well exceed the recommended max COAL from the manuals. I read a little on-line and noticed it may not be that uncommon for 300 win mag bullets to be seated further back from the lands, and I also read that COAL could exceed 3.340" as long as the cartridges can still fit in the mag (I am not asking for reloading advice). However, when I look inside the receiver I can see where 2 ID threads still show (where the barrel threads into the receiver), whereas, on my other sakos I never see more than a maximum of 1 full thread remaining. I then measured the barrel length (bolt closed with cleaning rod through the bore method) and it's exactly the same length as my AIII 7mm rem mag. The crowns of the guns look different, looks like a 11 degree taper OD to ID on the AIII 7mm, and zero degree tapper OD to ID on the AV 300 but with a small chamfer right at the bore entrance. I'm wondering if the gun has been re-crowned and not threaded all the way back to normal to keep the barrel length to spec. The barrel markings all look normal including the Garcia Import except it doesn't have a heraldic lion head stamp (which might be might be normal for the AV barrel). I would appreciate comments on my observations from you the experts...Thanks!
     

  2. stonecreek

    stonecreek SCC Secretary Forum Owner SCC Board Member

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    The Sako magazine accommodates cartridges just a tad over 3.6". The .300 Win Mag was designed to work in .30-06 length magazines of 3.35", but this requires very deep seating of the bullets; it begs to have its bullets seated longer. Your .300 Win Mag appears to have about the same leade as my L61R, allowing you to seat out to almost 3.5" (depending on the ogive of the particular bullet). This is very desirable in that it allows you to use a larger charge of slower powder and in effect makes the pressure vessel a bit larger. I just checked, and my 180 Accubonds are seated even longer -- 3.54". Standard cartridge OAL is for factory cartridges meant for any rifle, not for handloads meant for a particular rifle.

    It's difficult for follow your description of the crown. Perhaps you can post a photo? The only crown I've seen on Sakos of A-V vintage and older is a flat muzzle with a bevel on the outside and another bevel at the bore.

    Since belted cartridges are designed to headspace on the belt (at least on the initial firing), it is nearly inconceivable that someone somehow removed and replaced the barrel and left a gap between it and the bolt. Cut a thin strip of electrical tape the same width as the belt on your cartridge. Wrap it around the belt of a case and chamber the case. If the tape isn't crinkled up by the lip of the chamber then there would seem to be something wrong.

    Can't say if the A-V barrel should have the Finnish Lion Head -- A-V's are a bit too recent for me to have had much dealings with them.
     
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  3. m995

    m995 Well-Known Member

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    " I'm wondering if the gun has been re-crowned and not threaded all the way back to normal to keep the barrel length to spec." If the barrel wasn't threaded tight to the action it would be loose. Sako factory barrels have a forcing cone type throat similar to revolvers, that will give you long COAL.
     
  4. 16b410

    16b410 Well-Known Member

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    My newest is an early '80's AIII. No lion's head on it either.
     
  5. Sakogun

    Sakogun Active Member

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    Stonecreek:
    The reference on your L61 seated out past 3.5" is reassuring, and I'll definitely try the tape...great idea. Thanks.

    Hopefully the attached image will help: left side is AIII 7mm & right side is AV 300. On the older models I'm always accustomed to seeing the crown beveled as you described. My 85 finnlight is just like the AIII.

    M995 - That's what I've been wondering - may be the picture will help.

    16b410 - perfect thanks.
     

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  6. m995

    m995 Well-Known Member

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    Just checked an AV in 30-06, 90 degree muzzle without lions head. My 75 in 300WM coal is 3.510 with 155 scenar"s. 3.454 with 190 MK HPBT
     
  7. m995

    m995 Well-Known Member

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    M995's & 75's have recessed crown, so if you have a late AV it very well could be factory. The AV from above post is in the 570K serial #'s
     
  8. Sakogun

    Sakogun Active Member

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    That answers all my questions and now time to go to the range tomorrow and see how well it shoots....I can't wait.

    It's always nice to learn more about Sakos. Thanks M995 and others.
     
  9. Sakogun

    Sakogun Active Member

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    The photo I previously posted shows the recessed crown you described on the left, whereas the 300 on right is 90 degree muzzle (I like your descriptions better). My AII 300 is serial #533XXX.
     
    Last edited: Oct 17, 2014
  10. Sakogun

    Sakogun Active Member

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    Two corrections (I definitely was not paying attention tonight) - the 300 is an AII and the 7mm reference is my L691....my mistake if that confused anyone.
     
  11. Clint

    Clint Member

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    I know your were not looking for loading advice, but wanted to throw someinfo I learned when loading my 300 win mag.

    As far as reloading the maximum COAL really has no bearing on what the gun manufacture decision in chambering a rifle as far as where the lands are. When Sako chambered your rifle they have to account for several bullet weights and designs which will place the ogive (the part of bullet that first engages the lands)of the bullet all over the place with different brands weights etc. To compound this problem the 300 win mag (and all belted magnums) headspace off the belt instead of the shoulder which possibly adds more stacked tolerance.

    I wouldn't worry to much about how far the bullet is from the rifling on a hunting rifle, sure you can adjust some tweaking your loads, but the 300 win mag (and all belted magnums) are designed, and made with function and reliability in mind. The only way your going to be able to have a chamber that you could seat bullets to lands would be a custom chamber cut with a specific bullet or weight of bullet in mind.

    When I was loading for 300 win mag I used Barnes X 180gr bullets which I recommend seat to reloading manual specs with function from magazine etc of main concern that will still allow you some tweaking. Use a Lee factory crimp die this will give you more consistent start load pressure which is one of the main reasons for seating bullets close to the lands. I hope this helps also you think a 300 winmag is bad a weatherby magnum headspaces off the belt then has outrageous amount of freebore to increase velocity making seating depth a moot point !!
     

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