C.O.L. A.O.L. B.T.O. ??

[maggragg]

Hello

I´m quiet new to reloading and there are some thing that are confusing me.

When I want to measure loaded cartridge I thougt that the best way it to measure from the base of the cartridge to the ogive of the bullet to get the most uniformity for each cartridge. Is that not the B.T.O. lengt?

And as I understand, then O.A.L or the over all length is from the base of the cartridge to the tip of the bullet?

What is then C.O.L.?

Seating depth is then what, wich measurement, the B.T.O?

Chamber length is the length from the action to the lands?

These things are confusing me a little. To find the freebore I have to find the max lengt of the loaded cartridge that will allow me to close the bolt and measure the cartridge then, That lengt is then the lengt that gives me freebore zero?

And what is then the Headspace exactly and how do I measure it?

And also the shoulder diameter and the base diameter?
And what is Leade?

What tools should I have to measure all these sizes.

I have a S-T industries digital Caliber

Hope somone can give mi some help with this /ubbthreads/images/graemlins/crazy.gif

 

[abinok]

Ive only got a second... so hopefully others will fill in the gaps.
COL is the length from meplat(bullet tip) to head of case.
AOL is the length from case mouth, to head, or alternately an evil empire responsible for the "dumbing down" of the internet... however, their free cds make excellent shotgun targets.
BTO is base to ogive... in this instance however, the base in question is on the bullet, not the cartridge.
headspace on most cartridges is measured from the datum point (or middle point) on the shoulder to the head. Theres a number of ways to measure it, but the most accessable is the stoney point gauge.
base diameter is the max diamerer in front of the extractor grove.
Shoulder diameter is the diameter at the junction of the shoulder, and case body.
Freebore, throat, leade.... all area in front of the case mouth, and while not interchangeable... are all talking, mostly about the same area. The # you are looking for, is the bullet Jam length... or the measurement from the head to the ogive at which the ogive of the bullet makes light contact with the lands.
Freebore would be the distance you seated your bullets back (deeper into the case) from this #
The leade is the angle area at the very origin of the lands.

Get the stoney point headspace gauge, and ogive inserts for the calibers youre loading for, and you will be good to go.

 

[Buffalobob]

If you are new to reloading I suggest that most of the stuff you mentioned does not need to be measured at your point on the learning curve. You should not have to measure headspace, shoulder diameter nor base diameter. A decent set of reloading dies takes care of all of the brass measurements except case lenght and trim to lenght. Measuring bullet bearing surfaces, lenghts, weights etc is not very critical for shooting animals under 1000 yards.

Seating depth is important. There are many Rube Goldberg methods of determining when a bullet actually contacts the lands that do not require buying any measuring tools. Once you know that you can pretty much work with the COL or keep a dummy round available for setting your seating die.

 

[maggragg]

Thanks Abinok

Answered most of my questions, knew most of this, but was´n sure.

I know I don´t use everything in this, but I always want to know everything perfect and realoading is included.

I was wondering this because I wanted to know which tool I should buy me. Including the stoney point tool.

There are always good answers on this forum.

For under 1000y shooting, which factors are most important in realoding conserning accuracy?

 

[Buffalobob]

The most important thing is to select two or three bullets that have the correct characteristics for the shooting that you do. These bullets should have a reputation for accuracy. For example Nosler partitions have a reputation for penetration and controlled expansion but not accuracy. For shooting a moose at 100 yards a partition would be a great choice but at 900 yards it might not be so great. A lot of people use match bullets at long range because of the accuracy factor

Then select a couple of powders and a couple of primers. I usually test bullets and powder first and find the best bullet powder combination. I then may test that load with a different primer. Finally, I work on seating depth of the bullet. I measure both horizontal and vertical dimensions of each group. I don't pay much attention to horizontal dispersion. I stop tinkering when I find an accuracy and velocity that is acceptable to me. Often times I do not test different primers and seating depths because I am satisfied with what I have found and do not need more accuracy for what I am hunting. If I am hunting antelope at 1000 yards then I pretty much need a load that is less than 0.5 MOA. If I am hunting elk at 1000 yards then I can get by with something less than 1.0 MOA. If I am hunting buffalo at 50 yards then accuracy means nothing and all I care about is bullet mass, penetration and speed. Try to remember what you have set out to do and that is not shoot bughole groups but to place a bullet accurately in an animal.

As far as the brass goes, if you buy quality brass such as Norma or Lapua you don't need to do much to it. Remington brass will need flashholes uniformed and primer pockets uniformed. Different pieces of brass grow at different rates and I detest having a few pieces of brass that are too long and the rest being the right length. That is probably the only thing I really get weird about is the brass length and trimming brass. I think it is very important. I think weighing powder is important although most evidence suggests that a tenth of a grain here or there is not so important. I think that sizing the brass the same way every time is important.

You should understand that I am only a hunter, and I am pretty stoneage when it comes to reloading. Most people spend way more time on it than I do.

 

[maggragg]

Thanks for this buffalobob

Here we shot polarfox, marders and sometimes seals.

They are the most difficult to shoot, they stick theyr head out of the sea for about a minute and then back down again, so headshot is the only option, so there is better to have a good accuracy.

And I also plan to shoot at paper at long range but I think I will buy me a Tikka T3 Tactical riffle in .308 for that and for the hunting.

Some of the realoding stuff like neck trimming I don't think is importand with a factory rifle, but maybe?

Iwant to get the most out of the riffle so I try to learn what is important and what is not so important.