Finding COL procedure question...

Discussion in 'Reloading' started by RickInFL, Aug 11, 2013.

  1. RickInFL

    RickInFL Active Member

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    Hi all...

    I'm new to reloading rifle but not pistol and am about to reload my first .270 Win cartridges, I have Sierra #1820 130 gr Game King, Sierra #1830 130 gr Pro Hunter and Nosler 130 gr Ballistic Tip that I'd like to compare out of my Model 70 but am having a heck of a time trying to figure out if I should use the COL listed in my manuals or measure off of the lands and exactly just *how* to measure off the lands. I've read so many different methods that my brain is now totally confused and have ordered the Hornady Lock'N Load COL gauge along with the Comparator set but they will not be delivered until late next week and I'd really like to hit the range tomorrow since I somehow managed to sneak a weekday off.

    So....

    I found a fired case that held just the right amount of tension to hold the bullets loosely and stuck the bullet into the case mouth so that the bullets were very long, chambered the rounds and gently pulled the cartridge back out and measured. I did this 15 different times using 15 different bullets from each bullet type (yes 45 times!) and averaged the COL of those 15 cartridges and then deducted .010 for my starting COL. After going through this procedure I read more info and now I am at odds to use these COLs or just start with the data in my manuals?

    Thanks.
     
  2. Varmint Hunter

    Varmint Hunter Well-Known Member

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    While you are waiting for your equipment just use the reloading book info and go have some fun.

    BTW - the distance off the lands will be different for each different box of bullets due to the different nose profiles. Averaging all the bullets together tells you nothing. Once you have your measuring equipment you can make a chart for each different bullet. Generally, any given bullet of the same manufacturer, type & weight will remain fairly consistent from box to box.

    It is not a bad idea to re-check the distance to the lands once in awhile because throat erosion will cause the dimension to change.

    Lastly, don't be fooled into thinking that rifles only shoot best with bullets loaded close to the lands. Accuracy nodes can be found at almost any distance if you actually look for them. I own several rifles, factory and custom that shoot very well with bullets loaded wayyyyy off the lands. Typically, bullets that are loaded to a length that fits into the magazine of a factory rifle will be way off the lands.

    My hunting buddy prefers Weatherby Mark V rifles. Ammo that fits in the magazine is often .250" off the rifling. You would be amazed at how well he gets those rifles to shoot with a preferred handload.

    For a hunting rifle, I would start at magazine OAL and then seat bullets progressively deeper (within reason) until I found an OAL that produced smaller groups.
     

  3. RickInFL

    RickInFL Active Member

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    Thanks Varmit, pretty much the plan I thought I'd end up going with ... I appreciate the feedback.
     
  4. Iclimb

    Iclimb Well-Known Member

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    I use a cleaning rod. Now you have to plug the end so it doesn't slip over your bullet or if you let it slip over you bullet you have to mark the bullet, Do a little math to figure out how far it's moving. I used the plastic jag and then I cut off the part for the patch basically to plug the hole in the end of the cleaning rod. Now put your Bolt in your gun and squeeze the trigger so the firing pin is not cocked (Unload it, of course) Stick the cleaning rod down the end of the barrel so it touches the bolt face and make a mark with a sharpie on the cleaning rod where the end of your barrel is. Now take the bullet that you are using with no case, remove your bolt and put the bullet in the barrel use a pencil to push it so it touches the lands. With the bullet on the lands and slight pressure on the pencil holding it their, insert the cleaning rod back down the barrel until it touches the bullet, you can push it out of the lands and push it back so you get it right where you want it, then make a mark on the cleaning rod again at the end of the barrel.

    This distance between the two marks on your cleaning rod should be your coal, to the lands. It's pretty simple, it's the same principle that the Frankfurt arsenal kit uses which in my opinion is a better setup than the Hornaday, but...

    You can do this with each type of bullet that you plan on using and that should give you a great place to start, on the lands of course.
     
  5. benchracer

    benchracer Well-Known Member

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    +1

    That is pretty much what I do and it works very well. This method will give you a base-to-tip COAL. If you want to know the base-to-ogive length, simply load a round to the base-to-tip COAL and measure it with your comparator. Mostly, I prefer to use the base-to-tip measurement anyway.
     
  6. RickInFL

    RickInFL Active Member

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    I did the cleaning rod down the muzzle measurement as well, I've done this for pistols also.

    What's a good off the lands starting point after finding the COL ... .020" or longer? These are for hunting loads.
     
  7. Iclimb

    Iclimb Well-Known Member

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    Too many variables to list; gun, bullets, barrel specifics....

    Basically it will relate specifically to your gun. It'll shoot different types of bullets differently. I suggest you click on me rifle, barrels, ballistics forum and read the sticky from berger bullets. This is a suggestion for their bullets exclusively but may give you a spot to start.
     
  8. benchracer

    benchracer Well-Known Member

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  9. RickInFL

    RickInFL Active Member

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    Excellent!

    That's exactly the information I am looking for, thanks a ton guys.