Cartridge OAL

MagnumManiac · Rookie Member Joined: Apr 03, 2008 Posts: 9

Lester,
The answer you need is this.
All this about 'into' or 'just off' the lands is hogwash!

Most, if not ALL hunting bullets work best when there is a 'jump' of between .015"-.100", and quite a lot more in Weatherby rifles. (Which doesn't affect accuracy in these rifles).

The most user friendly method of determining COL for YOUR RIFLE is to place the EXACT bullet you intend on using in the chamber, muzzle down at first, place a pen or other object in behind the bullet and hold it in place.
Then, with your cleaning rod, make sure it has a flat end/attachment, put it in the barrel from the muzzle, without dislodging the bullet, place a mark flush with the crown with a fine felt tipped pen on your rod.
Remove the rod, and then the bullet, replace the bolt in your rifle and close it, insert the cleaning rod again to touch the bolt face and mark the rod again as before. This normally takes a couple of minutes to perform.

Using a vernier, measure from the OUTSIDE of your first mark to the INSIDE of your second mark, this is the MAXIMUM COL for that particular bullet, you can then use this measurement to set your dies
to place the bullet back .015", .020", ,025" etc from the lands. You will also need to check if this measurement is compatible with your magazine length, if not, follow my procedure below.

You will have to do this with ALL different bullet styles you will use.

In most cases you will need to find the measurement that your rifle likes, and remember, if you load past what your magazine will handle, all you have is a single shot.

My method is to load to within .010" of magazine length, and work backwards in .010" increments until I find the sweet spot, there is no use loading longer than the rifles magazine will allow unless the rifle is used for varmint/target work, where single loading isn't important in taking shots at game.
Cheers.
MagnumManiac.
Very Happy

English Mike · Posted: Thu Dec 11, 2008 9:46 am Post subject: Re: Cartridge OAL

The Hornady tool is the simplest to use & very accurate too.

I use it in conjunction with the Hornady bullet comparator, as minor inconsistencies in the bullet's meplat can skew the measurements.
Using it means I can easily load bullets with different ogives to the same distance from the lands.
It's how far the bullet's bearing surface is from the lands that is important & not the cartridge OAL.

ElyBoy · Posted: Thu Dec 11, 2008 10:34 pm Post subject: Re: Cartridge OAL

My method is kind of like using Kentucky Windage with a fixed sight, but it has always worked for me.

I first use the OAL listed in my reloading books, so I know that I won't kill myself.

Then I start with low powder weight to start, and work up until I get my best accuracy.

Then, by trial and error, I will find the "sweet spot" as one of the guys said, and then, it's "look out ten ring!!!"

Eric

44marty · Posted: Tue Mar 02, 2010 10:21 am Post subject: Re: Cartridge OAL

The Nosler reloading manual describes an easy way to check bullet seating depth to the lands. Take an empty, unprimed sized case (the bullet should drop easily into the case). Flatten the case mouth slightly by pressing against a table or bench. Color the bullet all over with a magic marker. Force the bullet a short way into the case mouth by hand, then chamber the round in your rifle. Extract the round. Pull the bullet out of the case. There will be a mark left where the case scraped the magic marker off the bullet. Seat the bullet by hand back into the case until this mark just lines up with the case mouth. measure the cartridge overall length. This is the length at which the bullet just contacts the lands (rifling).
CAUTIONS
- loading cartridges with bullets at, or very close to, the lands will increase
pressure.
- this procedure is specific to the particular bullet and must be repeated for each bullet profile
- before loading you MUST check to see that this cartridge overall length will feed through your magazine
- some bullets are much more accurate seated farther away from the lands
- I am not convinced that seating bullets as close as possible to the lands is really the answer to tight groups. My .300 Weatherby (Vangaurd) has an extreme amount of "freebore" (distance to the lands) BUT holds spectacularly tight groups, easily sub 1/2 MOA.

toddco · Rookie Member Joined: Sep 09, 2009 Posts: 20

Here is a way to find your chamber length to see what length you can have your brass. I did this because in my .204 savage the chamber is so long i could not load the bullets out far enough to reach .020" from the lands. So here goes. Take an old piece of brass, cut off half of the neck and save the ring, split the ring, resize the brass, put a bullet in it, then pull it in and out a few times so you now have a piece of brass that a bullet will slide in and out of fairly easily, now put the bullet in the brass, leaving it out as far as you can, put the ring over the bullet just over the ogive, put the chamber measuring cartridge in to your rifle and close the bolt. You should see that the ring has been pushed back on the bullet. Do this a few times until you get a consistent measurement. AFTER YOU HAVE AND OVERALL MEASUREMENT YOU NEED TO SHORTEN YOUR BRASS .008 TO .010 THOU TO ALLOW FOR STRETCHING WHEN YOU FIRE A ROUND OFF!!

Happy shooting