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Thread: COL

  1. #1
    Member shimano 33's Avatar
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    Question COL

    I believe I have read enough threads on COL to keep my head spinning for a week..but I believe I fully understand the concept of it, as well as its limitations (magazine length, pressure changes, ect..)

    My question(s) is once you do figure out your length from the lands and get started on your quest for that perfect bullet seating depth how do you go about ensuring you hit this exact number every time you seat a bullet? Do you NEED to have a comparator for this action? Also, would you measure after each and every seating to ensure this length isn't changing, or would the die do its job on putting the bullet where it needs to go every time?

    Something else I would like to figure out, is what is the best method to actually figure out when your on the lands? Could this be achieved by getting a case to barely accept a bullet and then slowly close the bolt until the action seats the bullet for you?..and then measure what you get?

    Im sill new to this and figured Id better ask before it gets any warmer out

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    There are several ways of going about this from special gauges to closing the bolt on a case with a loose fitting bullet. Once you have set your die, it is good to go for that bullet.

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    You can do without a Comparator, and establish the COL, (using one of the Several ways) to the lands, then measure to the Tip, minus it, but use the same bullet for adjusting your seating die

    Better, to measure the completed length with a Comparator, and record that reference point to the lands, minus it, and set the seating die, because thereafter, you can use the comparator for other bullets.

    Yes, on your last paragraph, but keep in mind, that there are variances, in your measurements, and in seating individual cartridges, as well as diffs in Ogives.

    For my purposes the important thing, is that I'm OFF the lands, which is why I like .030, then go from there, maybe more, but not much less. This stuff sounds very EXACT, but IME, it ain't.

    For a comparator, I recommend the Sinclair Hex type. It looks like a Hex Nut, with different bore caliber holes in the flats, and can be placed over the bullet, and the cartridge can be measured on your calipers, Opposite Flat, to case head Simple, and BOOTIFUL .

    Smitty of the North
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    Yeah, I doubt if your are getting more than close from bullet to bullet from the same box as most bullets aren't that exact. Many times the magazine will limit OAL before you get to the lands anyway.

  5. #5
    Member shimano 33's Avatar
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    Thanks Smitty and Rbuck. I figured I would first just seat a bullet that would barely fit in my mag and go from there.

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    I used the loose fitting bullet in empty case method to find the lands in my meat rifle.

    Be advised that many bullets from the same lot, same mfr, same box will have a variance, bullet to bullet, between the ogive point you measure with a comparator and the tip of the bullet.

    Think about that a minute.

    I can pretty well tell you my favorite Sierra bullet comes out of a machine that makes 20 bullets at a time.

    I will also say cheaper bullets will have more variance between the ogive point and bullet tip than more expensive bullets.

    How fussy is your rifle? What is your minimum group size really?

    If you are a national level bench rest competitor, yep, measure every bullet. If you are gunning for moose with a mid priced hunting bullet with a production rifle, maybe not. If you are going for mountain sheep and want to reach 300 yards with a production rifle, probably measure all your bullets, sort them by length and only load the ones at the most common length +/- .001".

    For hunting food I think trigger time at the range from field positions without a lead sled is more important than dialing your load in to the sixth decimal place.

  7. #7
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    Quote Originally Posted by swmn View Post
    For hunting food I think trigger time at the range from field positions without a lead sled is more important than dialing your load in to the sixth decimal place.
    I agree.

    How well you can shoot your rifle, from "field positions" is more important to success than small groups. Off Hand practice, for example, is humbling. I KNOW, and I have the opportunity to shoot off-hand regularly.

    It's also important that your rifle is sighted in, and that you have some idea of elevation at various ranges.

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

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