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Thread: Advice Please - Bullet seating depth

  1. #1

    Advice Please - Bullet seating depth


    I'm in the process of working up a load using Hornady .308 150 grain SSTs. I also have some Hornady Superformance 150 grain SST factory cartridges.

    I've done the measurements and the factory loaded bullets are seated 0.152" off the lands. They're seated down to the crimp ring. The COL is 2.742".

    I'd like to reduce this jump to 0.070" which will give me a COL of 2.825" I've checked visually and it looks like this length will fit in the rifle magazine. I'll seat some bullets tomorrow and confirm this.

    However, the Hornady Handbook states a COL with this bullet of 2.735". Most other data sources (i.e. Nosler website for a jacketed 150gr BT) show a COL of 2.8".

    My questions are:
    1. Assuming the rounds fit in the magazine, will exceeding the COL stated in the Hornady Handbook and elsewhere present any problems?

    2. Should these bullets be seated down to the crimp ring?


  2. #2
    Why would you like to lengthen the oal by 70 fow, it may not shoot at that oal, my advice would be to load to 2,800 oal as this is a good place to start, more than likely they will shoot very well

  3. #3
    Seating a bullet further out increases case volume so for the same powder charge you would be lowering the pressure & also the muzzle velocity.
    It does enable you to get more powder in the case if you so wish to compensate & get the power back up. So answer to your question 1 is "Probably not".
    Answer to no. 2 --- You needn't seat down to the crimp ring - you can seat to the length that you choose & crimp anywhere along the parallel length. - just don't over crush it in the process. (I never crimp into a canelure, prefering to have the solid support to the crimp & not deforming the case excessively by going into the canelure. I use a light crimp so as not to crush the bullet jacket).
    What is important is that the case neck bears fully on the parallel sides of the bullet. The start of the boat tail should be inside the case void - not the neck.


  4. #4
    The bullet doesn't need crimping, fl resizing will have more than enough neck tension, crimping can damage the bullet and best used for semi auto rifles apparently

  5. #5
    If you load them to the 'crimp ring' and use the seating die to give a slight taper crimp, it will help with smooth feeding.
    Are you competing in bench rest ?
    If not, why worry about loading any closer to the lands ? Just load them to where hornady's designers meant them to get loaded to.
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  6. #6
    Quote Originally Posted by swarovski View Post
    The bullet doesn't need crimping, fl resizing will have more than enough neck tension, crimping can damage the bullet and best used for semi auto rifles apparently
    A point I will gladly contest. ~Muir

  7. #7
    I thought you might andy , crimping can make fps more consistant but not nessasarily more accurate apparently but ive never or will ever bother, i shoot my ammo out to 1000yds to very good effect and my loads usually shoot consistently less than 20fps, more often than not less with very basic kit.
    Last edited by swarovski; 26-12-2014 at 20:59.

  8. #8
    Thanks all for your answers:


    I don't plan to increase the overall length by .070". I want to seat the bullet so it's 070" (or thereabouts) off the lands. This means I'll exceed the published OAL. I plan to fl resize and not crimp.


    I'm going to be using N135 which I think is on the fast side for this bullet design. Some of the published charge weights look quite high, more like those I've used before for a lighter bullet with a smaller bearing surface. With this in mind, increasing the case void may not be a bad thing if it keeps the pressure down.


    No, I'm not a bench rest shooter, I just want to get the best results I can. A jump of .152" in my rifle seems excessive to my mind and perhaps if I can reduce this I can achieve great things


  9. #9
    CH -- One thing to remember is that if your bullets are seated long, the tips will end up closer to the end of your magazine --- Keep an eye open for slamming due to the recoil dislodging the bullets, especially if you don't crimp.
    Do let us know how you get on with the load with N135. - 308 is usually a very forgiving cal & 150 grain bullets nearly always work very well & are tolerant to variables. For years I always used N140 & got very consistent results.


  10. #10
    CH. Have a look at the thread 'Blackened Cases .243', that I started on 6/6/14. It is a bit of a drag to read as there are 46 posts. However, if you can stick it out, there are several issues that I learned, which you could find relevant and hopefully helpful.
    A pessimist is an optimist with experience.

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