Coal/cbto

[N2TRKYS]

How is it a "Better Use of Time" when both methods take exactly the same amount of time, and one gives more reliability on the measurement that matters?

I think it's one of those scenarios - do whatever's working for you. Hell, I've had awful luck with Nosler and am doing whatever I can to stay away from them from here on out.

I only load for 8 rifles, but I’ve never had any issues with accuracy while shooting Nosler bullets in any of them. Weird, that you’ve had bad luck with them. I hope you find something that you like.

 

[Cahunter805]

I use the VLD stem to seat all bullets. I would switch your stem if you have one.
I also only measure CBTO and find Berger’s to be pretty consistent.

 

[OXN939]

How is it a "Better Use of Time" when both methods take exactly the same amount of time, and one gives more reliability on the measurement that matters?

I think it's one of those scenarios - do whatever's working for you. Hell, I've had awful luck with Nosler and am doing whatever I can to stay away from them from here on out.

So question. Assuming your bullets have negligible variation in overall length, is there any advantage to loading to CBTO versus COAL?

 

[Brendan]

So question. Assuming your bullets have negligible variation in overall length, is there any advantage to loading to CBTO versus COAL?

Yes.

The measurement that matters is jump - bullet distance from the lands. The bullet contacts the lands at the ogive, not the tip. Therefore, you're looking for consistency in where the ogive is in your loaded rounds. On some bullets, you might be fine measuring COAL, on others you won't be.

Look at it this way - you might load bullets to a consistent COAL, but have a varying CBTO, therefore each loaded round would have a different jump / distance to the lands. Some bullets are better than others at OAL consistency, but why use a measurement that'll work fine in some cases, and not in others?

 

[Tahoe1305]

Yes.

The measurement that matters is jump - bullet distance from the lands. The bullet contacts the lands at the ogive, not the tip. Therefore, you're looking for consistency in where the ogive is in your loaded rounds. On some bullets, you might be fine measuring COAL, on others you won't be.

Look at it this way - you might load bullets to a consistent COAL, but have a varying CBTO, therefore each loaded round would have a different jump / distance to the lands. Some bullets are better than others at OAL consistency, but why use a measurement that'll work fine in some cases, and not in others?

I believe this is an accurate assessment.

 

[OXN939]

Yes.

The measurement that matters is jump - bullet distance from the lands.

Check, so. If bullets are dimensionally close to identical and you use a COAL gauge to determine how far they are off the lands, doesn't that eliminate the problem? I definitely wouldn't load soft points or bullets that have significant variation in their lengths like that, but as someone mentioned earlier, I know some manufacturers specifically recommend loading to COAL rather than CBTO

 

[Brendan]

Check, so. If bullets are dimensionally close to identical and you use a COAL gauge to determine how far they are off the lands, doesn't that eliminate the problem? I definitely wouldn't load soft points or bullets that have significant variation in their lengths like that, but as someone mentioned earlier, I know some manufacturers specifically recommend loading to COAL rather than CBTO

Yes, if you use a bullet that is consistent in all measurements, it won't matter if you measure one or the other. I haven't used either Hammer or Cutting Edge, but I'd bet bullets like those you'd get good results because they're all copper, CNC machined in a lathe. But it comes back to what I said earlier - the measurement that matters is the ogive, and when it hits the lands.

But, also want to make sure we're not criss-crossing terms. I use the Hornady tool initially to find distance to the lands. Lock it down, pull it out of the action, put on a comparator and measure CBTO, not COAL. Repeat 4-5 times for consistency and that's my starting length (You can also disassemble your bolt and look for a smooth bolt close). I then measure COAL once just to make sure it'll fit in my mag, and then start load development, probably backing off .010" or 020" to start based on the CBTO measurement. Adjust my seating die until my starting CBTO measurement is as desired based on the measurements taken off of the Hornady tool and then adjusted for jump. Might go back to touching, might just start working backwards.

Also - just so we're on the same page, measuring COAL is base of the brass to tip of the bullet in a set of calipers. No gauge needed here. CBTO on the other hand requires a comparator and mount for your calipers because you're not measuring from the tip.

 

[Cahunter805]

Measuring off the bullet tip for COAL is usually less consistent due to tips being deformed or inconsistent. I prefer measuring off the Ogive for consistent jump to the lands.
Some people will go as far as to measure bullets from base to Ogive and sort them also.

 

[N2TRKYS]

So question. Assuming your bullets have negligible variation in overall length, is there any advantage to loading to CBTO versus COAL?

No. You can measure it any way you want. Nothing is perfect, but I’ve always had great luck with the COAL. It’s never proven to give me a reason to change.

 

[OXN939]

Yes, if you use a bullet that is consistent in all measurements, it won't matter if you measure one or the other. I haven't used either Hammer or Cutting Edge, but I'd bet bullets like those you'd get good results because they're all copper, CNC machined in a lathe. But it comes back to what I said earlier - the measurement that matters is the ogive, and when it hits the lands.

But, also want to make sure we're not criss-crossing terms. I use the Hornady tool initially to find distance to the lands. Lock it down, pull it out of the action, put on a comparator and measure CBTO, not COAL. Repeat 4-5 times for consistency and that's my starting length (You can also disassemble your bolt and look for a smooth bolt close). I then measure COAL once just to make sure it'll fit in my mag, and then start load development, probably backing off .010" or 020" to start based on the CBTO measurement. Adjust my seating die until my starting CBTO measurement is as desired based on the measurements taken off of the Hornady tool and then adjusted for jump. Might go back to touching, might just start working backwards.

Also - just so we're on the same page, measuring COAL is base of the brass to tip of the bullet in a set of calipers. No gauge needed here. CBTO on the other hand requires a comparator and mount for your calipers because you're not measuring from the tip.

Rgr. All makes sense. I'm currently shooting LRXs and just got a shipment of hammers, both of which have all been within a few thousandths of each other for all of them I've measured. Hornady CBTO tool definitely on the shopping list- being a poor student, I do suppose I'll be sticking with the COAL technique for the time being. Thanks for the thorough explanation!

 

[mvrk28]

No. You can measure it any way you want. Nothing is perfect, but I’ve always had great luck with the COAL. It’s never proven to give me a reason to change.

Wrong.

 

[wind gypsy]

Just to make sure folks aren't talking past each other here... Ultimately a die with the appropriate seating stem for a given bullet should be seating bullets to be consistent BTO and have some variance in COAL based upon nose length variance. I doubt that N2TRKYS is saying he adjusts his die for each round so they measure the same COAL but rather he documents load data based off COAL rather than a BTO measurement. From N2TRKYS prior posts, he seems to primarily use rem M7s which are more constrained by COAL than most so loading to something that works at mag length is probably more practical than knowing the exact jump.

OP, trying to seat to the same COAL is a waste of time and is actually counter productive in obtaining consistent ammo. If your process is sound, you should be seating to consistent BTO which is what matters.

 

[N2TRKYS]

Wrong.

Has proven to be wrong for me.

 

[N2TRKYS]

Just to make sure folks aren't talking past each other here... Ultimately a die with the appropriate seating stem for a given bullet should be seating bullets to be consistent BTO and have some variance in COAL based upon nose length variance. I doubt that N2TRKYS is saying he adjusts his die for each round so they measure the same COAL but rather he documents load data based off COAL rather than a BTO measurement. From N2TRKYS prior posts, he seems to primarily use rem M7s which are more constrained by COAL than most so loading to something that works at mag length is probably more practical than knowing the exact jump.

OP, trying to seat to the same COAL is a waste of time and is actually counter productive in obtaining consistent ammo. If your process is sound, you should be seating to consistent BTO which is what matters.

I like Model Seven rifles but use and load for several different brands and models. I haven’t found that it makes enough difference between the two for me to change.

Just cause other folks have luck with one system doesn’t mean the other way is wrong. I’ve had folks tell me that you can’t get accurate ammo without neck sizing only, but that’s not proven to be true from my experience. Doesn’t mean that their way is wrong, just not what I choose to do.

 

[wind gypsy]

I like Model Seven rifles but use and load for several different brands and models. I haven’t found that it makes enough difference between the two for me to change.

Just cause other folks have luck with one system doesn’t mean the other way is wrong. I’ve had folks tell me that you can’t get accurate ammo without neck sizing only, but that’s not proven to be true from my experience. Doesn’t mean that their way is wrong, just not what I choose to do.

The OP indicated he was adjusting seating die depth for each round so they got consistent COAL measurements. Can you confirm that you leave your seating die at a given setting and don't adjust each round? That is the basis for the number of people in this thread disagreeing with you.

Measuring COAL rather than BTO is a less precise way to measure bullet jump. It can work just fine in many cases as you attested, I don't think people are arguing that.

 

[N2TRKYS]

The OP indicated he was adjusting seating die depth for each round so they got consistent COAL measurements. Can you confirm that you leave your seating die at a given setting and don't adjust each round? That is the basis for the number of people in this thread disagreeing with you.

Measuring COAL rather than BTO is a less precise way to measure bullet jump. It can work just fine in many cases as you attested, I don't think people are arguing that.

I don’t move my seating die. What I’m saying based on my testing, the bto measurement is not always the most accurate.

Now the question is, how many thousandths allowance are acceptable in your practice? One, two, three thousandths?

 

[wind gypsy]

I don’t move my seating die. What I’m saying based on my testing, the bto measurement is not always the most accurate.

Now the question is, how many thousandths allowance are acceptable in your practice? One, two, three thousandths?

BTO is certainly a more accurate way to measure bullet jump. You're measuring to the part of the bullet that contacts the lands so you don't have nose length variance at play.

As far as allowance for variance, it depends what variance you're referring to. BTO variance round to round? COAL variance round to round? Assumed jump distance based upon COAL vs actual jump due to nose length variance? As long as you're seating consistently and jumping a bit, I don't think it matters much. For example if you measure jump based on COAL and think you're jumping 0.040" but are actually jumping 0.050" or .030" who cares as long as it shoots well. If you're intending to jump say .015" or less and you're basing jump on COAL, its possible you could end up loading all the way into the lands when you thought you were jumping them.

 

[N2TRKYS]

BTO is certainly a more accurate way to measure bullet jump. You're measuring to the part of the bullet that contacts the lands so you don't have nose length variance at play.

As far as allowance for variance, it depends what variance you're referring to. BTO variance round to round? COAL variance round to round? Assumed jump distance based upon COAL vs actual jump due to nose length variance? As long as you're seating consistently and jumping a bit, I don't think it matters much. For example if you measure jump based on COAL and think you're jumping 0.040" but are actually jumping 0.050" or .030" who cares as long as it shoots well. If you're intending to jump say .015" or less and you're basing jump on COAL, its possible you could end up loading all the way into the lands when you thought you were jumping them.

I say that bto is not necessarily the more accurate way, depending on the bullets you’re shooting. My testing has shown me that, so you do what your testing has shown you.

I was referring to your bto measurements from round to round.

 

[Cahunter805]

CBTO is definitely a more accurate way of measuring. Load some bullets to all the same CBTO and then measure the COAL. The COAL is gonna be all over the place due to nose length differences, inconsistencies in tips etc. I’ve seen differences in COAL of .010 or greater.

 

[N2TRKYS]

CBTO is definitely a more accurate way of measuring. Load some bullets to all the same CBTO and then measure the COAL. The COAL is gonna be all over the place due to nose length differences, inconsistencies in tips etc. I’ve seen differences in COAL of .010 or greater.

Nope, not always.