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Thread: Seating depth?

  1. #1

    Seating depth?

    Ok, so getting close to starting reloading and wondering about seating depth.....

    my lyman book gives an oal of 2.735" for my particular bullet (.308 with a hornady interlock 150gn). Having just tried a bullet at this length in a fired case it looks a bit short? The cannelure is pretty much totally in the case neck at this length. Should I keep it at book length as a starting load or go a little longer?

  2. #2
    hi i have recently been loading .308w 150gn interlocks, i found that 44gns of n140 is a nice light load and produced the best results, i then measured the OAL of a sako hammerhead 150 grain round and seated my honadays to the same depth of 2.65 inches, this produced a very accurate round, the cannelure is inside the case and can not be seen,

  3. #3
    Unless you're doing loads customised/optimised for your chamber/throat dimensions, you shouldn't e able to see the canelure on the bullet. Remember, it's designed as a crimping groove, so the top edge of the canelure should be just covered up by the case mouth.
    You can't say muntjac without saying, Mmmmmm.

  4. #4
    I use interlocks in a few calibres and ignore the canelure completely even when crimping
    fine if it works in your rifle but I have mine seated about a mm below the groove for best results

    do what is best in your rifle
    try the stated OAL
    if it is fine leave it alone
    if not...play around with seating depth

  5. #5
    Quote Originally Posted by Harry mac View Post
    Remember, it's designed as a crimping groove, so the top edge of the canelure should be just covered up by the case mouth.
    This is not necessarily true. It is a structural feature. It is the "Interlock": What locks the core to the jacket. With some rounds it is meant for crimping as cartridges designed for a tubular magazine or revolvers. A good rule of thumb is that if the bullet you are loading has a point on it (VS flat nose) it was never intended to be used as a crimp groove. Likewise smaller bores like 6mm, 7mm, 6.5mm. When reloading for a high velocity rifle that has no mechanical need for a crimp you ignore it.~Muir

  6. #6
    Quote Originally Posted by Muir View Post
    This is not necessarily true. It is a structural feature. It is the "Interlock": What locks the core to the jacket. With some rounds it is meant for crimping as cartridges designed for a tubular magazine or revolvers. A good rule of thumb is that if the bullet you are loading has a point on it (VS flat nose) it was never intended to be used as a crimp groove. Likewise smaller bores like 6mm, 7mm, 6.5mm. When reloading for a high velocity rifle that has no mechanical need for a crimp you ignore it.~Muir
    Thanks guys, think I'll load them at book length to start with then and hopefully leave it at that.

  7. #7
    Quote Originally Posted by palmer_mike View Post
    Thanks guys, think I'll load them at book length to start with then and hopefully leave it at that.
    I load those 150 grain spire points and just loaded them to book length which was 2.735 as per what you are doing. I'm using Reloader 15 just for info.

    A long time back I did waste some part of my life messing about with seating depth but it made no significant difference that I could see (though sometimes I thought there was a difference and got all excited but it was never repeatable nor statistically significant) and I have two loads with those bullets - book min which I use as a practise and plinking type load and book max which I used to use as my deer load - and both those loads shoot way better than I ever could. My money says all the loads in between will perform just as well.

    So, unless you've time on your hands and enjoy the load development process, and many do, then I'd say load them to 2.735 and get shooting.
    For self catering accommodation on the Isle of Lewis please visit:
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  8. #8
    Quote Originally Posted by Muir View Post
    This is not necessarily true. It is a structural feature. It is the "Interlock": What locks the core to the jacket. With some rounds it is meant for crimping as cartridges designed for a tubular magazine or revolvers. A good rule of thumb is that if the bullet you are loading has a point on it (VS flat nose) it was never intended to be used as a crimp groove. Likewise smaller bores like 6mm, 7mm, 6.5mm. When reloading for a high velocity rifle that has no mechanical need for a crimp you ignore it.~Muir
    +1 for very good info.

  9. #9
    Quote Originally Posted by Muir View Post
    This is not necessarily true. It is a structural feature. It is the "Interlock": What locks the core to the jacket. With some rounds it is meant for crimping as cartridges designed for a tubular magazine or revolvers. A good rule of thumb is that if the bullet you are loading has a point on it (VS flat nose) it was never intended to be used as a crimp groove. Likewise smaller bores like 6mm, 7mm, 6.5mm. When reloading for a high velocity rifle that has no mechanical need for a crimp you ignore it.~Muir
    I don't mean that you have to use it, but even Hornady's own advertising blurb describes the canelure as a crimping groove. According to them, it works in conjunction with the interlock ring to help retain the core.
    You can't say muntjac without saying, Mmmmmm.

  10. #10
    +1
    yup thats what its for , but some do and can use this as a point that just happens to give them a nice load and group if this do's then happy days .
    if you are near someone that can tell you by way of a aol gage then get it measured if not then go with what you data says, you could go down the route of blacking a bullet and use'g this in a dummy case to get your oal , this will leave a mark in the black ink at the point that the bullet hits the lands at the ogive of the bullet, then use your callipers to tell you how long your chamber or how long the round is from the tip to head now then say start at 10 thou back off and work back until you find that sweet node spot for your loaded round ,my sako likes a jump with 150's but that's mine.


    Quote Originally Posted by SA shooter View Post
    +1 for very good info.
    Originally Posted by Muir
    This is not necessarily true. It is a structural feature. It is the "Interlock": What locks the core to the jacket. With some rounds it is meant for crimping as cartridges designed for a tubular magazine or revolvers. A good rule of thumb is that if the bullet you are loading has a point on it (VS flat nose) it was never intended to be used as a crimp groove. Likewise smaller bores like 6mm, 7mm, 6.5mm. When reloading for a high velocity rifle that has nomechanical need for a crimp you ignore it.~Muir

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