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Thread: Bullet Seating Question

  1. #1

    Bullet Seating Question

    Hi guys,
    a bit of advise required, Ive started working out my new .308 reloads, ive measured the OAL and got 2.348", im not particularly concerned about having the bullet right upto the lands but there is only aprox 100 thou of the bearing surface in the case neck at full length, i was wondering this so i know when fiddeling with OAL if the groups are a bit poor what max length I can go to, what is the minimum amount of contact needed for, 1. the bullets to be secure in the case and 2, get enough grip for sufficient pressure to give proper ignition and combustion of the powder, point 2 may not be an issue but I had it in mind that if the bullet pops out of the neck too easily it may be a problem, the rifle is a rem 700, bullets are 165 speer boat tail soft points, powder is varget, primers are fed gmm

    mike

  2. #2
    This may be a typo. on your part, but your maximum OAL of 2.348" is only 59.6mm. The .308 cartridge OAL is normally about 2.800"/71mm.

    I get the readings on Vernier calipers wrong so often myself that I measure both in Imperial and Metric just to double check. To return to your point, if you have a rifle with a long lede or deep throat it's sometimes difficult to get near the rifling with boat-tailed bullets, so consider standard flat-based SP's instead. There's really no advantage in using boat-tails over short ranges .... say within 250 yards.

    If you full length resize cases usually you can get by with only 5-6mm of 'grip' on any FBSP bullet. Even with the shorter 125-130gr weights this will get you to just 2mm short of the rifling in most rifles.
    If I'm going to be accused of it then it's just as well I did it.

  3. #3
    thansk for the reply, I didnt put that I was measuring with a bullet compariter so the measurement is to the ogive not to the tip of the bullet, if i measure to the tip its 2.980, I dont have a full length resize die, just a neck die, so if i aim to get 5mm + of contact i'll be ok?

    mike

  4. #4
    I like one caliber's worth of neck bearing on the bullet for general use/hunting cartridges.~Muir

    PS: Worrying about neck tension as it relates to ignition and pressure is a very intelligent avenue of thought. More important than many people give credit for...
    Last edited by Muir; 09-12-2011 at 13:52.

  5. #5
    have you tried seating the bullets 'deeper' in the case? You'd be surprised by how that might tighten the groups, even though the BR girls all argue the bullet should be almost falling out of the neck. Also, you don't want to seat them so far out that you can accidentally knock the bullet out whilst out stalking, or even worse, pulling the bolt back with a primed and filled case, powder spilling out in the magazine, and bullet sitting happily in the throat

  6. #6
    [QUOTE=Muir;292985]I like one caliber's worth of neck bearing on the bullet for general use/hunting cartridgesQUOTE]

    that's my principle too, works a treat, and I like to start my loads at around 90% of max, then work upwards...usually find that 90% and 1 diameter deep is about as good as a group as you get...don't know why though...and I'm not recommending others try that process (disclaimer!)

  7. #7
    thanks guys for the replys, most constructive, I am planning to start with aprox .275 bearing surface in the case neck and work shorter once ive worked up the load, a little shorter than 1x.308 depth but the next box of bulets will be flat base which will give me plenty of length in the case although I assume i will need to work up the load again as there will be a greater length gripped by the case neck so pressure will be greater

    mike

  8. #8
    get yourself an oal gauge,cvomparator and modified case for your 308,its simple to use and you know exactly how far head is of the lands,its much more accurate way of measuring cartridges

  9. #9
    Quote Originally Posted by swarovski View Post
    get yourself an oal gauge,cvomparator and modified case for your 308,its simple to use and you know exactly how far head is of the lands,its much more accurate way of measuring cartridges
    ive got one

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