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Shocked at how much throat erosion

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  #1  
Unread 01-12-2008, 12:29 PM
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Shocked at how much throat erosion

I started shooting my 30-06 Ackley last November 2007. It's has a 26" SS Lilja barrel. My primer count indicated I've put about 700 rounds through it. I've got a great 180 BT/AB load and am currently working on a 200 AB/PT load for Alaska Brownie/Grizzly/Dall.

In the process of determing my Partitions distance to the lands, I decided I better see if/how much throat erosion I had. I looked at the original 180 BT/AB data since this is the original bullet I started with. I pulled the original 180 AB from it's primerless case after I remeasured it and compared the measurement w/ the data written on the side of the case. I then ran the same bullet through my process of determing OAL up against the lands. I reseated the bullet to the new OAL and HOLY COW! If I did my measurements and math correctly I've lost .13" in throat. I went back and double checked both the "before" OAL and Length to bearing surface (LtBS), then compared them both to the new OAL and LtBS;----.13"-----.

Is this normal? I figured I might get .02 to .04" but not a tenth plus.
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  •   #2  
    Unread 01-12-2008, 01:11 PM
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    Throat Erosion

    What powder are you using? I experienced severe throat erosion and firecracking in a 7MM Mag. using Reloader 22. Switched to H4831, same velocity, pressure and accuracy, no more erosion or cracking.
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      #3  
    Unread 01-12-2008, 01:16 PM
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    I'm not surprised at all. In the off season, I usually recheck all of my rifle throats the same way you did. Many of my rifles have seen .010" of erosion and sometimes more. Think of what 1,000 rounds of any magnum cartridge will do to a throat. Many barrels are "toast" by that time unless treated gingerly. You know - shooting only short strings to allow barrel cooling and careful cleaning using the usual benchrest methods.
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      #4  
    Unread 01-12-2008, 02:15 PM
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    My load is 68.5 gr of Rel 25 for the 180'ers going 2997 fps in Win cases and Fed 210M primers seated .015" off lands.
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      #5  
    Unread 01-12-2008, 06:26 PM
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    I've got about 2400 rounds through my 30-06. Throat has advanced less than .02"

    Barrel is a Douglas stainless steel, #7 contour, 1/10 twist. most of the loads have been moly'd 190-210gr match bullets, under 60-62gr RL22.

    I wonder if the moly shields the metal from some of the effects of heat/pressure?
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      #6  
    Unread 01-12-2008, 07:13 PM
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    6.5x284-throat erosion per 100 rounds? - Benchrest Central Forums

    Interesting thread on this very subject on BR central. Guys are tracking about .03 for every hundred rounds.

    BH
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      #7  
    Unread 01-12-2008, 11:48 PM
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    Quote:
    Originally Posted by Alan Griffith View Post
    I started shooting my 30-06 Ackley last November 2007. It's has a 26" SS Lilja barrel. My primer count indicated I've put about 700 rounds through it. I've got a great 180 BT/AB load and am currently working on a 200 AB/PT load for Alaska Brownie/Grizzly/Dall.

    In the process of determing my Partitions distance to the lands, I decided I better see if/how much throat erosion I had. I looked at the original 180 BT/AB data since this is the original bullet I started with. I pulled the original 180 AB from it's primerless case after I remeasured it and compared the measurement w/ the data written on the side of the case. I then ran the same bullet through my process of determing OAL up against the lands. I reseated the bullet to the new OAL and HOLY COW! If I did my measurements and math correctly I've lost .13" in throat. I went back and double checked both the "before" OAL and Length to bearing surface (LtBS), then compared them both to the new OAL and LtBS;----.13"-----.

    Is this normal? I figured I might get .02 to .04" but not a tenth plus.


    Shouldn't have been that much erosion but mileage may very. If the barrel was cleaned and not allowed to get too hot, it should have gone 1500 or so before getting rough. My 300 win mag eroded .020" after 1100 rounds. What method are you using to determine the seating depth/throat measurement?
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