bullet seating and COAL

[Darklyte27]

So of course, bullets arent perfect, the tips on 175 SMKs and pretty much any bullet arent some stick up higher and some are flat like they should be. I set my 308 bullet seater for 2.800
some measure 2.820 2.830 etc what do you do?

I am sure if they were flat they would measure 2.80

[ocabj]

This has been covered many times. The answer to 'what do you do' is 'nothing'. If you are simply basing your seating depth on the base to tip length, then just set the seater to where you get a decent average close to 2.800" and be happy.

[Darklyte27]

thats what i was doing and i know the tip will vary but was just wondering if anyone else does it differently.

[ocabj]

The only time you should care what the base to tip measurement is if you are running close to exceeding the magazine's dimensions. Otherwise, you should simply be making sure that the base to ogive measurement is coming out the same all the time. That's the measurement that matters the most.

[Jicko]

Use a quality seating die, many of us use Redding's Competition Micrometer Seating die.... great die...

And then just keep a consistant setting, you will be fine...

If you take a batch of raw bullets, just measure them, you will see length variance too...

Lastly, to comfort yourself... measure your COAL NOT by the tip of the bullet, but from the OGIVE... and you will see quite consistant correlated COAL.

[Darklyte27]

ya i have the s die randall was talking about. how do you measure the ogive?

[1lostinspace]

So of course, bullets arent perfect, the tips on 175 SMKs and pretty much any bullet arent some stick up higher and some are flat like they should be. I set my 308 bullet seater for 2.800
some measure 2.820 2.830 etc what do you do?

I am sure if they were flat they would measure 2.80

measure the bullet OL then the brass OL then subtract the diameter of the bullet.
Dies have nothing to do with it.

[Timberwolf]

ya i have the s die randall was talking about. how do you measure the ogive?

with a comparator

http://www.cabelas.com/spod-1/0044517.shtml

[Timberwolf]

measure the bullet OL then the brass OL then subtract the diameter of the bullet.
Dies have nothing to do with it.

And what would that show?

[swerv512]

are you guys saying that COAL is measured from the ogive, not tip to base?? in my spper manual it does give COAL but it doesnt say how it's measured.

[1lostinspace]

And what would that show?

the COL that a bullet should be.

[1lostinspace]

This has been covered many times. The answer to 'what do you do' is 'nothing'. If you are simply basing your seating depth on the base to tip length, then just set the seater to where you get a decent average close to 2.800" and be happy.

+1 on that it takes too long to waste time trying to get things perfect odds are it's still more accurate then the shooter.

[xrMike]

are you guys saying that COAL is measured from the ogive, not tip to base?? in my spper manual it does give COAL but it doesnt say how it's measured.

No, Cartridge OverAll Length means from base to tip. Any measurement you see in a reloading manual is going to be that one (COAL). It's only important if you're concerned with loading rounds that will fit into a magazine. And yeah, it's also helpful to know COAL so that you don't seat your bullets too deep, which could cause overpressure problems...

But the more serious and careful reloaders are more concerned with measuring from base to ogive. Because the ogive is the first part of the bullet to contact the rifling in the barrel. And by adjusting that distance (from ogive to rifling) you can produce rounds that are best suited for your particular gun. More accurate than store bought, or more accurate than ammo that was loaded to the max. recommended COAL (per reloading manuals).

[swerv512]

i guess i have to get one of those bullet seating tools because i cant figure out my rifle's ogive to base measurement... any suggestions.

[30Cal]

i guess i have to get one of those bullet seating tools because i cant figure out my rifle's ogive to base measurement... any suggestions.

Seat a bullet long in a resized case. Stuff it into your chamber using your thumb. If you need to use a thumbnail or a tool to get the cartridge back out, the bullet's touching the rifling--seat deeper by 0.005" and try again. When the cartridge falls out of the chamber from gravity alone, you're clear of the rifling, but still very close. Measure you COAL. Now you can adjust the jump for that type of bullet by adjusting COAL by the same amount (I would actually put the dummy cartridge aside so that you don't have to do this every time you go back to that same bullet).

This is the simplest, cheapest and by far the most repeatable way to measure where the lands are that I know of.

Adjusting jump is a lot easier & quicker with either a micrometer seating die or a bullet comparitor that goes on your caliper. The longer way around is:

1. set the die for zero jump (either by doing the above or using the dummy you saved from last time) and make a cartridge to match. Measure COAL and decide what you want for jump (say 0.020")
2. Use your bullet puller to move the bullet out farther than your desired jump (that original COAL + 0.020" or longer)
3. Move the seating plug up
4. Now you can adjust the seating plug down till you get the COAL that gives you the jump you want.