Base to ogive inconsistency?

[cornfedkiller]

Typically when I reload, I just check my COAL every 10-15 rounds just to make sure I'm still pretty close to what I'm going for and go out and shoot (I'm not a bench guy, so if I can kill animals at 500 and under, that's all I care about). Last night I was doing a little reloading and had some time to kill so I busted out my comparator and decided to just check every bullet for the heck of it.

Most bullets would be within .005 (between 2.215 and 2.22), but every once in a while I'd get a bullet that would be 2.245 or higher.

Whats the reason for that inconsistency? The bullet? My dies? My press?

Nothing I'm losing sleep over, just curious...

 

[Pickettpuncher]

I would make sure that the calipers are not faulty. I would also run those back thru the seating die in case for some reason you didn’t seat them far enough. Mine usually run about .002 max. I wouldn’t expect the bullets to vary that much unless you got a bad batch of seconds

 

[Wrench]

Many things add up. You have tolerance in your metrology. You have tolerance in the die stem, neck tension, press ram....etc. powder crush can be an issue.

As a rule, I don't trust a dial (or digital) caliper to be more than. 002" accurate. The flex in the jaws and slide can be that much or more.

Most of the screw on fixtures such as the hornady can stack another. 001" easily.....so just in tolerance stack you're half of the deviation.

 

[packer58]

Could also be that the necks on some of your brass is work hardened more that others if you don't anneal regularly. The harder the brass the more force it takes to seat the bullet .......and the additional force required creates some level of flex in your equipment.

 

[doverpack12]

I set long and short aside and use them for fouling shots or practice but having them separate ensures I can observe how they impact and not have to wonder if something strange happens.

 

[Vandy321]

I have noticed an inconsistent coal when crunching powder...sometimes had to seat that bullet twice. It's funny how the same powder charge can sit different in a case due to the shape of the grains. With light neck tension that could be one explanation.

You mention BTO but also COAL...if it's BTO that's inconsistent, that rules out the above and narrows it down to calipers/comparator gauge or tolerances from the manufacturer.

 

[Roksliding]

Spin the cartridge make sure it’s sitting flush in the comparator and jaw of the caliper (I’m sure it is)

I rotate the case 3 times while seating, run case up 1/3ish bring back down rotate 30 degrees, run back up 2/3ish back down rotate 30 degrees and then run case all the way up.

Also double check that the primers are slightly below cartridge base

Take the comparator off zero your caliper, and set it all up again, zero it on a known loaded case.

Take a napkin and clean out the inside of your seating die

Sometimes I have a couple .001-.003 long, I just run them through the seating die again and make sure I am bottoming out.

 

[Dos XX]

Take 10 or 20 bullets from your box of bullets and measure the bto on the bullets. Then you will know if the variation is in the bullets.

Also, if they are vld type bullets, you need a vld seating stem in your die

 

[BRTreedogs]

Guessing maybe you're seating stem is shorter then the tips of your bullets. And its pressing on the tips instead of ogive.
Tips are inconsistent anywho and I would suggest measuring cbto other then checking mag length.

Are you running a high bc long ogive bullet?

Pull your seating stem and check with a bullet if its making it to the ogive.

 

[4ester]

Measuring COAL is your problem more then likely. Your seating die doesn’t touch the tip of your bullet….. so why are you using it as a measurement.

Measure BTO (base to ogive) will tell you what’s really going on. If you still have issues after that….then we regroup.


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[cornfedkiller]

Guessing maybe you're seating stem is shorter then the tips of your bullets. And its pressing on the tips instead of ogive.

I have the one from hornady that's made for those bullets.

Measuring COAL is your problem more then likely. Your seating die doesn’t touch the tip of your bullet….. so why are you using it as a measurement.

The question doesn't come from measuring the COAL - I know there's a bunch of variation there, I just mentioned that's how I typically did it because I didn't own a comparator, but now that I do, I see a little variation in the CBTO from time to time and it just made me curious.

 

[BRTreedogs]

I have the one from hornady that's made for those bullets.



The question doesn't come from measuring the COAL - I know there's a bunch of variation there, I just mentioned that's how I typically did it because I didn't own a comparator, but now that I do, I see a little variation in the CBTO from time to time and it just made me curious.

Do you have you die setup for a slight cam over?

 

[4ester]

I have the one from hornady that's made for those bullets.



The question doesn't come from measuring the COAL - I know there's a bunch of variation there, I just mentioned that's how I typically did it because I didn't own a comparator, but now that I do, I see a little variation in the CBTO from time to time and it just made me curious.

Ok, I was confused by your term comparator.

Do your bullets come out of a red or black box?

Compressed loads? I had issues with ELDX tips hitting the seater before it touched the seating ring…..

Usually I’m within +/- .0005 with the yellow boxes.


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[Wrench]

Ok, I was confused by your term comparator.

Do your bullets come out of a red or black box?

Compressed loads? I had issues with ELDX tips hitting the seater before it touched the seating ring…..

Usually I’m within +/- .0005 with the yellow boxes.


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How are you measuring 5 tenths? I have a 50 millionths indicator and me breathing on the stylus can bring one to two tenths just in temp change.

 

[cornfedkiller]

Do you have you die setup for a slight cam over?

I'm not exactly sure what that means. I have it set so that I run my lever all the way down? Is that not the correct way to do it?

Do your bullets come out of a red or black box?

Red

 

[BRTreedogs]

Start at minute 3

 

[4ester]

How are you measuring 5 tenths? I have a 50 millionths indicator and me breathing on the stylus can bring one to two tenths just in temp change.

Most digital calipers go to .0005 resolution. (1/2 a thou). And I’m using LE Wilson Chamber Type on some.


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[4ester]

I'm not exactly sure what that means. I have it set so that I run my lever all the way down? Is that not the correct way to do it?



Red

I would check to make sure the bullet tips arent jamming into the die. Sometimes you can take a small drill bit and add some clearance.

I have seen a few Hornady lots that have that much variation in the same box.


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[LaHunter]

Remember, the bullet seater makes contact with the bullet in one location, your comparator makes contact with the bullet in a 2nd/different location. Neither of these are the same as the bearing surface of the bullet. Most likely your bullets have some variability to them along with the other suggestions already posted

 

[cornfedkiller]

Remember, the bullet seater makes contact with the bullet in one location, your comparator makes contact with the bullet in a 2nd/different location. Neither of these are the same as the bearing surface of the bullet. Most likely your bullets have some variability to them along with the other suggestions already posted

Makes sense. As I mentioned in the original post, its nothing I am concerned about as my accuracy is always good enough for me, but it was just something that made me curious.. wasn't sure if its something more expensive dies would take care of, better brass, better calipers, etc..

I have no interest in being a benchrest shooter at this point in my life, but understanding all the little details and what affects what interests me, which is why I asked..

Thanks for all the answers!