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OAL -- how do you measure it?

plains scoutplains scout Member Posts: 4,563
edited January 2005 in Perry Shooter Competition Shooting and Reloading Forum
I have used the tool that is suppose to measure it, and it does a pretty good job. However, how I did it before was to seat it longer than factory then run it (empty casing and no primer) into my rifle. Then pull it out and under good light and with a magnifying glass study to see if I could ascertain any "marks" on the bullet from rifling. If I saw some I would set the next bullet a hair deeper until I reached that point where I could see marks on one bullet and then on the next one I seated I could see none. Just a RCH micro measurement from the rifling. That is where I would then set the die permantly for that rifle. IT worked very well.

How do you set the optimum OAL for your rifle?



How vain it is to sit down to write when you have not stood up to live.
Henry David Thoreau

My friend is one... who takes me for what I am.
Henry David Thoreau
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Comments

  • ContacFrontContacFront Member Posts: 1,113 ✭✭✭✭✭
    edited November -1
    I have not begun to mess with seating my bullets out close to the lands. I figure I would come up with a load that shoots good first before messing with OAL.

    I plan to use the same method you described Plain.

    Do you measure OGIVE or OAL? I use a lot of sierra match king bullets and I find them VERY inconsistant due to the hollow point and plan to start measuring the OGIVE instead of just OAL.
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    Buy the sinclair seating tool,..it will give you an exact "at the land measurement" and you can back off from that if you wish.

    OAL will vary greatly with the HPBT pills as the jacket is drawn around the core and then cut off? The only way to make these the exact same length is with a meplat trimming tool. You are far better off buying a comparator and using the ogive as your measuring point.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • ruger270manruger270man Member Posts: 9,361 ✭✭
    edited November -1
    im just gonna use the method plains mentioned, its what I read about in the manuals so far, sounds like the best best for getting it closest to the bore.

    sniper.gifhappy.gifanim_sniper.gif

    "I will no longer debate a liberal because I feel they are beneath contempt. Just communicating with one contaminates a person." - whiteclouder
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  • rimfire72rimfire72 Member Posts: 901 ✭✭✭✭
    edited November -1
    quote:Originally posted by JustC
    Buy the sinclair seating tool,..it will give you an exact "at the land measurement" and you can back off from that if you wish.

    OAL will vary greatly with the HPBT pills as the jacket is drawn around the core and then cut off? The only way to make these the exact same length is with a meplat trimming tool. You are far better off buying a comparator and using the ogive as your measuring point.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
    I second that,its easy to use. If you have any problems just call the people at Sinclair and they will help you. Everyone I've dealt with there has been knowledgable and very friendly.

    buycoolshirts_1825_31216154.jpg
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  • ruger270manruger270man Member Posts: 9,361 ✭✭
    edited November -1
    is the sinclair tool the one that goes inside of a case, then you chamber it to get the measurement?

    sniper.gifhappy.gifanim_sniper.gif

    "I will no longer debate a liberal because I feel they are beneath contempt. Just communicating with one contaminates a person." - whiteclouder
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  • hardtymshardtyms Member Posts: 140 ✭✭✭
    edited November -1
    use a black sharpie marker on the bullet you are seating you can see your little marks much better you dont want it to touch if it does your pressure will raised dramatically just make sure your bolt does not close to tight also once you get a load you prefere I digital caliper everything and keep a log, caliper the OAL of the bullet/shell write down the powder and charge/grains and which bullet and put it into your recipe book before long you will have 5 different powders and 10 different bullets and weights and you wont have to scratch your head if you dont reload for a lengthy amount of time

    Load on Sunday shoot all week!!!
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  • D.K.D.K. Member Posts: 291 ✭✭✭
    edited November -1
    I simply use the recommended C.O.L. in the reloading
    manuals for the specific bullet in question. COL is
    measured from the tip of the bullet to the flat at the base
    of the brass. It's the total length from one end to the other
    and is best measured with a caliper.

    You guys are not really discussing C.O.L. but rather the distance
    from the bullet to the rifling. And yes, doing this will result
    in a longer COL. It's also dangerous...because most reloading
    info in the load books presuppose a given amount of freebore,
    and that's what you change each time you mess with C.O.L.!

    The proper method is to determine your C.O.L. for the distance from
    the rifling you want your bullet to have, then work up from a LOWER starting load to prevent excessive pressures! Since bulets of
    of different manufacturers have different shapes, a bullet
    collimater from SINCLAIR or other supplier will measure this
    for you. If you don't have the proper tools, don't wing it, because it just isn't safe! Hopefully you guys have discovered and are using a method of keeping pressures at a safe level.

    Respectfully,

    D.K.
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    as the bullet is seated out toward the lands, the internal powder capacity is increased and therefore pressure is slightly reduced. This is up until the bullet is seated to make contact with the rifling whereas no movement prior to engaging the lands takes place. However,..in all my time seating bullets at and INTO the lands, the charges are always higher when the accuracy load is found, due to the internal powder capacity being increased. As long as you havn't way overcharged the case,..pressure increases will be within acceptable limits. This is how 99% of all BenchRest competitors seat their rounds, as it also helps to square up the round inside the chamber and align it with the centerline of the bore.

    ruger270, no this is NOT the threaded case system like the stony point tool. The sinclair tool uses a fired case from your rifle with the primer still installed. The first stop is set by dropping a bullet down the bore until it contacts the rifling and then the tool is inserted and the stop is locked in place. next,..a fired case is inserted in the chamber, and the tool is reinserted, and allowed to butt up to the case head/primer. Now the second stop is slid into position and locked in place. The calipers take the outside measurement of these 2 stops,..and then add the bullet length (because the tool measured to THE BASE of the bullet while it was engaging the lands). It's simple and repeatable. You will find your rifles EXACT length to the lands every time. At this point,..you can take a '"comparator" and get the measurement from the casehead to the ogive. Now,..no matter what different bullet you wish to load,..you simply seat that bullet until you have the same measurement from casehead to the ogive of the new bullet,..and that bullet will also be seated at the lands.

    If you wish to leave a small gap,..then back that measurement down by .010-.020" and you will be seated just away from the lands.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • easygo6easygo6 Member Posts: 1,465 ✭✭✭✭✭
    edited November -1
    The Sinclair tool sounds sweeet!

    I've been using the method described by plains scout with great success.

    Problem is having to re-adjust the dies if you change bullets. I keep an empty case with the bullet inserted at the proper depth as a gauge to re-set my dies. I write the OAL of the guage down so that if in the process of using it as a gauge I could bump/shorten the OAL.

    I need the precision shooting die so I can write down a measurement for each production run of bullets I buy. Then just 'dial it in'!!
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    easygo,..that is the MAJOR benefit of micrometer seaters and sizers. When your throat erodes some,..just seat the bullet a few .001"s longer and you are back at the lands again. And as you stated,..you write down the marks for each and every bullet,..and the die can be used for multiple loads in multiple rifles with NO set-up time after the initial work. That in itself makes their price worth it.

    why chase the game when the bullet can get em from here?....
    Got Balistics?
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  • n/an/a Member Posts: 168,427 ✭
    edited November -1
    quote:Originally posted by easygo6
    The Sinclair tool sounds sweeet!

    I've been using the method described by plains scout with great success.

    Problem is having to re-adjust the dies if you change bullets. I keep an empty case with the bullet inserted at the proper depth as a gauge to re-set my dies. I write the OAL of the guage down so that if in the process of using it as a gauge I could bump/shorten the OAL.

    I need the precision shooting die so I can write down a measurement for each production run of bullets I buy. Then just 'dial it in'!!




    EZ...you should not have to change up your dies with different bullets. RCBS dies contact the bullet down on the taper of the bullet at the same diameter as the rifling for that caliber round. If you are using a bullet with a longer or shorter taper, it will just extend either further or shorter into the bore. The distance between where your bullet's outside diameter (same as the diameter of the rifling)contacts the rifling will still be the same distance. I'm not sure if that last sentence makes any sense...

    Eric

    All American Arms Company

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  • IconoclastIconoclast Member Posts: 10,515 ✭✭✭
    edited November -1
    Us old folks used to smoke the bullets and decrease the OAL by a smidgeon until a chambered round showed no signs of contact w/ the rifling. Obviously much slower than a dedicated tool, it does have the advantage of being pretty much free.

    One of my buddies used some sort of blue / purple layout ink found in machine shops.

    I would submit that not 1 shooter in 500 is going to realize any practical value from such extra steps. The exceptions being the BR types and those who *actually* hunt at loooooooonnnnnnngggggggg ranges. JMHO. But it has some psychological benefits, I suppose.

    "There is nothing lower than the human race - except the french." (Mark Twain)
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