Acceptable COAL variance

[Uffdaphil]

Fist time out newb. Seating 190g Nosler Custom Competition OTM the caliper length varies a little. Die is snugged down and some measure the correct 2.215. (300BLK subs for AR) I suspect the small open tips are not all that square. Many are .2145 or .2155. A few .2140 and .2160.

All fit 300BLK Pmags and are not for competition use. Are these numbers okay? What is a good +/- range?

 

[kmw1954]

Unfamiliar with that combo but if I have a target length of 2.250" I will allow a 2.253" or a 2.245" and not fret about it. That's what I'm doing right now with a 68gr 223.

 

[NedNederlander]

+ or - .003" is my acceptability range. I'm just using inexpensive equipment and components, also not measuring anything other than COAL. If I were to use expensive competition dies, presses, and components while using measurement tools for things like ogive and such, I'd want tighter numbers than .003"

 

[Uffdaphil]

Thanks. I probably should also get a new caliper. Mine is cheap and old.

 

[.308 Norma]

Die is snugged down and some measure the correct 2.215. (300BLK subs for AR) I suspect the small open tips are not all that square. Many are .2145 or .2155. A few .2140 and .2160.

I think you must have got your finger on the decimal point key at the wrong time there, Uffdaphill. The difference between 2.215" and .2145" is over 2 inches.
I suspect you meant 2.145", not .2145", and the difference 2.145" and 2.215" is only .070 inches. But seeing as how I don't load for the 300BLK, I don't know if I'd be comfortable with that or not. Maybe someone else that does load for the 300BLK will chime in and say whether or not 7/100ths of an inch is acceptable tolerance for COALs.

 

[Blue68f100]

Use your seating stem to see how consistent the OAL is. This will eliminate the varying tips.

 

[243winxb]

Single stage .005" Progressive .010" maximum. Best to measure on the bullets ogive.

Use your seating stem to see how consistent the OAL is. This will eliminate the varying tips.

This works after taking the stem out of the die.

 

[AJC1]

You will need a tool to correctly measure variation or consistency. Most bullets seat by ojive and that is also what makes contact with the leed. In match bullets I want perfect but will accept. 002. I do the same in pistol. If your making blamo for messing around maybe. 005. Neck tension and brass variations between headstamp and number of times fired will give you a wider window.

 

[Uffdaphil]

I think you must have got your finger on the decimal point key at the wrong time there, Uffdaphill. The difference between 2.215" and .2145" is over 2 inches.
I suspect you meant 2.145", not .2145", and the difference 2.145" and 2.215" is only .070 inches. But seeing as how I don't load for the 300BLK, I don't know if I'd be comfortable with that or not. Maybe someone else that does load for the 300BLK will chime in and say whether or not 7/100ths of an inch is acceptable tolerance for COALs.

Sheesh, did I ever mess up those numbers. The right measurements to compare are:
2.2140
2.2145
2.2150 - goal
2.2155
2.2160

 

[lordpaxman]

For my 5.56 AR I prefer +/- .005, and I know at the max I’m still .020” away from the lands. Do you know your max COL for your .300? That’s one of the considerations for determining +/-. For bolt or PR it’s a tighter tolerance, striving for +/- .003”. For plinking ammo +/- .010, given you’re not at max load, wouldn’t cause me to re-do those, but I’d try to determine what would be causing the variation. If you seat and crimp in one operation and have differing case lengths, it may be part of the problem. Neck tension can also affect seating depth to some degree. Good luck.

 

[Uffdaphil]

Looks like I will accept =/-.005 for now until I figure out the ogive measuring. Blammo is good enough for my first batch on the Rockchuker. I’ll set my sights higher next round. Thanks all for the input.

 

[Uffdaphil]

For my 5.56 AR I prefer +/- .005, and I know at the max I’m still .020” away from the lands. Do you know your max COL for your .300? That’s one of the considerations for determining +/-. For bolt or PR it’s a tighter tolerance, striving for +/- .003”. For plinking ammo +/- .010, given you’re not at max load, wouldn’t cause me to re-do those, but I’d try to determine what would be causing the variation. If you seat and crimp in one operation and have differing case lengths, it may be part of the problem. Neck tension can also affect seating depth to some degree. Good luck.

The cases were primed and trimmed beforehand by an experienced reloader near me. Case lengths are consistent. Neck tension I can’t judge. My test loads will be well below max until I build confidence on how to read pressure signs. Is not max COL in an AR the magazine length? My longest round -2.2160- still fits in the mag without binding.

 

[243winxb]

The seating stem/plug should not contact the bullets nose when seating. Should make contact on the ogive. Some bullet designs (VLD) may need a custum stem/plug .

Lee , but may work for other brands?* -

The Bullet Seater plug that comes with the die set is as close to generic as we can make it. If you find that the bullet seater plug deforms the nose of the bullet you are trying to seat, we can make a custom bullet seater plug to fit your bullet. For this we would need a sample bullet, payment of $8 plus any applicable taxes and Shipping/Handling. Current lead time is 4 to 6 weeks.

*Many times, you can fix this yourself through the use of a drill press. Secure the seater plug under a 3/32" bit and drill further into it. The distance should never be increased by more than 1/4". If this does not solve the issue, we recommend sending it to us.

A custom bullet seating plug can be ordered online.

Send the sample bullet to our address:

Lee Precision, Inc.
4275 Highway "U"
Hartford, WI 53027

https://support.leeprecision.net/en/knowledgebase

 

[AJC1]

The cases were primed and trimmed beforehand by an experienced reloader near me. Case lengths are consistent. Neck tension I can’t judge. My test loads will be well below max until I build confidence on how to read pressure signs. Is not max COL in an AR the magazine length? My longest round -2.2160- still fits in the mag without binding.

Measuring neck tension or seating force is a down the road skill. Just knowing it is the cause of variation is enough for now. Any of the comparator tools will work well. The hornaday tool seems readily available and reasonably priced... Sinclair makes basically the same thing... be careful to get the bullet pilots not the shoulder ones. Both can be used in the same tool.

 

[NMexJim]

Lock-N-Load® Bullet Comparator - Hornady Manufacturing, Inc

I quote Hornady:
"Measuring cartridge lengths across the bullet tips is not a reliable (or repeatable) method for measuring loaded rounds. Its common for variations of up to .025" to exist from one round to the next. Our Bullet Comparator measures rounds from the ogive to provide consistent, precise measurements. You can also use it to check uniformity of bullets from base to ogive."

Not counting the cost of a caliper, this set costs $34 and shipping. Don't drive yourself crazy measuring off the bullet tip. It's bad enough at the ogive.

 

[barnfrog]

Looks like I will accept =/-.005 for now until I figure out the ogive measuring. Blammo is good enough for my first batch on the Rockchuker. I’ll set my sights higher next round. Thanks all for the input.

No offense, but are you really bad at math? If your goal is 2.2150" and you are hitting between 2.2140" and 2.2160" then your variation is +/- 0.001". Think that over for a moment: you're only off by ONE THOUSANDTH of an inch in either direction. When folks are looking for the right seating depth they usually try increments of anywhere from ten to forty thousandths, and might fine tune increments of two or three thousandths. Competitive shooters might try to get finer than that, but for hunting rounds and the average shooter getting some trigger time, +/- 0.001" is just fine. Granted, you are measuring to the tip instead of the ogive, but you're still seating your bullets very consistently, which one should expect with the Rockchucker.

Take a sample of the bullets (not the finished cartridges) and see how much they actually vary. That's going to be a bigger source of variation than your technique or equipment if you're measuring to the tips.

Within the range of seating depths you are achieving I don't believe you will notice any reduction in accuracy unless you are shooting out to extreme distances.

And you can spend money on a comparator, but you don't necessarily need to. Google "measuring distance to lands" and you'll find ways to measure without spending the extra dough. Again, unless you are shooting extreme ranges, you'll be plenty precise.

 

[NMexJim]

No offense, but are you really bad at math? If your goal is 2.2150" and you are hitting between 2.2140" and 2.2160" then your variation is +/- 0.001". Think that over for a moment: you're only off by ONE THOUSANDTH of an inch in either direction. When folks are looking for the right seating depth they usually try increments of anywhere from ten to forty thousandths, and might fine tune increments of two or three thousandths. Competitive shooters might try to get finer than that, but for hunting rounds and the average shooter getting some trigger time, +/- 0.001" is just fine. Granted, you are measuring to the tip instead of the ogive, but you're still seating your bullets very consistently, which one should expect with the Rockchucker.

Take a sample of the bullets (not the finished cartridges) and see how much they actually vary. That's going to be a bigger source of variation than your technique or equipment if you're measuring to the tips.

Within the range of seating depths you are achieving I don't believe you will notice any reduction in accuracy unless you are shooting out to extreme distances.

And you can spend money on a comparator, but you don't necessarily need to. Google "measuring distance to lands" and you'll find ways to measure without spending the extra dough. Again, unless you are shooting extreme ranges, you'll be plenty precise.

That's true - you can make your own. If you have the time or inclination.

 

[Uffdaphil]

No offense, but are you really bad at math? If your goal is 2.2150" and you are hitting between 2.2140" and 2.2160" then your variation is +/- 0.001". Think that over for a moment: you're only off by ONE THOUSANDTH of an inch in either direction. When folks are looking for the right seating depth they usually try increments of anywhere from ten to forty thousandths, and might fine tune increments of two or three thousandths. Competitive shooters might try to get finer than that, but for hunting rounds and the average shooter getting some trigger time, +/- 0.001" is just fine. Granted, you are measuring to the tip instead of the ogive, but you're still seating your bullets very consistently, which one should expect with the Rockchucker.

Take a sample of the bullets (not the finished cartridges) and see how much they actually vary. That's going to be a bigger source of variation than your technique or equipment if you're measuring to the tips.

Within the range of seating depths you are achieving I don't believe you will notice any reduction in accuracy unless you are shooting out to extreme distances.

And you can spend money on a comparator, but you don't necessarily need to. Google "measuring distance to lands" and you'll find ways to measure without spending the extra dough. Again, unless you are shooting extreme ranges, you'll be plenty precise.

LOL. It’s not so much that I’m that bad at math, but that I’m not sure which precise measurements are important in reloading. The effect of just a +/- grain of powder seemed kinda nuts to me too at first.

 

[barnfrog]

LOL. It’s not so much that I’m that bad at math, but that I’m not sure which precise measurements are important in reloading. The effect of just a +/- grain of powder seemed kinda nuts to me too at first.

I guess my point in the bad at math comment was that you were saying you would "accept" +/- 0.005" when you were already getting +/- 0.001".

 

[Uffdaphil]

I guess my point in the bad at math comment was that you were saying you would "accept" +/- 0.005" when you were already getting +/- 0.001".[/QUOT

You are so right. Why do I think any jury would convict me of a math crime? My high school aptitude tests said math was my strong point!.

 

[NMexJim]

Are you a noob to this forum or to reloading? Or both? I'm just trying to gauge an experience level, so that we can start to make some hopefully helpful suggestions.

Are you wanting to shoot long range or something like 3-gun?

Any other reloading beside the Blackout? What kind of reloading equipments?

There is a ton of experienced based knowledge here.

 

[koni]

Thanks. I probably should also get a new caliper. Mine is cheap and old.

I would suggest a Scarlett or Mitutoyo for a caliper. Both are on the higher end of the spectrum ($100+ ish) but it’s a buy it for life item. I’ve also used the igaging ($40-60ish) but didn’t last more then 3years. That was everyday industrial use not reloading. I think the igaging would be just fine for reloading. +/- .001 tolerances for the igaging +/- .0001 for the others.
I currently use the Mituyoto 0-6” 500-196-30.

 

[Uffdaphil]

New to reloading. I’ve been reading this forum for years when info searches led me here, but mainly active on a couple of AR forums (not ARF). I bought a Rockchucker Supreme press about 4 years ago and got beaucoup primers, dies. powder and other loading kit when I found deals. While ammo was cheap the last few years I stocked up. With the current panic, ammo replacement cost finally made reloading really worth my time. My old eyes are too bad for precision competition. 3-gun? Maybe if they have an over 70, slow saunter division with lots of rest breaks. I want to load for the AR’s I like to build and shoot - .223, 308,300BLK and 6.8SPC. And save my primo factory ammo for defense and SHTF. Hopefully it won’t be needed and my heirs will get a pleasant surprise. I don’t shoot pistols, revolvers or my lever .357 enough to bother loading those.

 

[Uffdaphil]

I would suggest a Scarlett or Mitutoyo for a caliper. Both are on the higher end of the spectrum ($100+ ish) but it’s a buy it for life item. I’ve also used the igaging ($40-60ish) but didn’t last more then 3years. That was everyday industrial use not reloading. I think the igaging would be just fine for reloading. +/- .001 tolerances for the igaging +/- .0001 for the others.
I currently use the Mituyoto 0-6” 500-196-30.

Igaging is what I have. At least 10 years old and been banged around. Funny, that Mituyoto is the one I decided on an hour ago. Love the certified calibration option for + $20.

 

[koni]

Igaging is what I have. At least 10 years old and been banged around. Funny, that Mituyoto is the one I decided on an hour ago. Love the certified calibration option for + $20.

If you bought for Amazon be sure to check for counterfeits. There has been some posts about 3rd party sellers ripping people off. I hope you like it!