COAL Book vs. actual

[7887mm08]

So i decided im going to work up some loads on my rem788 in 222, want something different.
I have the sinclair cartridge length tool. Bullet im going to try is the speer 52 hp varmint.
Using the tool (which is a rod with 2 stops) it comes out to a max coal of 2.145" Book coal is 2.130"
Is it really possible that my chamber is that short?"
All other guns and calibers that i have used this method on were miles apart. Thanks and Happy New Year!

 

[Herzo]

In this case, the COAL is based on the length of the bullet, where the ogive begins (at the full diameter) and adequate support in the neck of the cartridge. Heavier bullets generally have a longer ogive and subsequently more of the bullet extends beyond the point of contact with the lands so COAL will be substantially longer.

 

[piie]

COAL = cartridge overall length- measured from bottom of the brass case (ehere headstamp is) to tip of bullet- measure with callipers- relevance is mostly to rnsure round fits in magazine.

CBTO = cartridge base to ogive, measured with some kind of tool that fits over the bullet tip close to ogive. Relevance is mostly to ensure the loaded round length will fit in your chamber and not jam the bullet into the lands

Dont mix/compare these measurements. Ony COAL measurement can be “shared” with someone else- CBTO is usually a relative measurement used for comparative purposes only and different from tool to tool due to contact on bullet ogive.

 

[fkimble@charter.net]

The twp most critical OAL's are not too long to fit mag and not too long to chamber. Bullet shape can affect fitment.

Frank

 

[HTSmith]

comes out to a max coal of 2.145" Book coal is 2.130"

Maybe I'm not understanding. Looks like your chamber (throat) is a little long to me?? Which would not be at all unusual for factory chamber. Will the length cartridge fit and feed?

 

[dhagerty40]

just remember, Book COAL's are based to fit the magazine, not the chamber..

 

[Herzo]

The "book COAL" is irrelevant to any particular rifle, rather it is a safe dimension for the casual reloader. A 0.015" variance should not be of concern.

 

[dellet]

Building on what others have said, 2.130” is maximum length based on the cartridge specifications when sent to SAAMI for approval, Generally longest allowed by magazine constraints.

If you load for very long, or step outside of the manuals and load bullets not listed, you will sooner or later find butlers that can not be loaded to magazine length, and will be listed with a shorter COAL.

This happens for two reasons. Either the bullet has a nose that is short and fat, hits the lands before 2.130”, or is so short that the bullet falls out of the case neck, or leaves so little in the case neck that it’s not practical to load.

Doing the measurement you are, finding the lands with each bullet, is what keeps you safe when working outside a book load. Keep doing that, because sometimes the books are wrong. I have seen that more than once, book COAL, has the bullet in a hard jam, at the specified length generally max SAAMI.

 

[topclass2017]

I use the Sinclair tool as described by the OP as well to determine theoretical max COAL for a particular bullet. When I come up with a number, my gut check is to figure out if I load to that length (minus whatever I dial in for jump), how much of the bullet will be in the neck, and how far the bullet will extend into the powder column. Both have kept me from using some bullets in certain rifles.

 

[Doom]

I am assuming that you measured the COAL at 2.145" with the bullet seated in the lands using this tool.

https://feeds.brownells.com/userdocs/learn/SinclairSeatingDepthGage.pdf

If the bullet is seated at 2.130" COAL you will be 0.015" off the lands.

This is not surprising as considering the vintage of the 222 cartridge.

A note on the use of "book" COAL. As others noted the 2.130" dimension is a specified maximum length for the Cartridge. It is part of the SAAMI specification for the 222 Remington. Reloading data may or may not be based on this dimension depending on the bullet/powder data. In fact, the dimension may be different for the same bullet in different load data sources.

 

[7887mm08]

FIRST, I realize what book coal is. It has been my experience that i can't use the max coal dimensions for 2 reasons: 1-magazine length or 2- chamber length is so long that case does not have enough bearing surface to grab bullet. In this case i have plenty of mag length and the lands are only .015" longer than book coal. Just seemed odd to me. Thanks for the replies.
'

 

[K22]

First thing I do before I load a bullet I haven't used before in a specific rifle is measure the base to ogive of a least three bullets in a given lot then use the longest as my starting point to work up a seating depth. I use a Frankfort Arsenal type tool for this purpose.

I have learned that the book value doesn't always work for a given rifle / bullet combo. For example, Sierra list the maximum COL for the 243 Win as 2.710. Their test load for the 85 BTHP was seated to 2.650. This will chamber easily in my Remington's which have long throats but will not chamber in my Tikka or Browning X bolt.

 

[Bill Norris]

First thing I do before I load a bullet I haven't used before in a specific rifle is measure the base to ogive of a least three bullets in a given lot then use the longest as my starting point to work up a seating depth. I use a Frankfort Arsenal type tool for this purpose.

I have learned that the book value doesn't always work for a given rifle / bullet combo. For example, Sierra list the maximum COL for the 243 Win as 2.710. Their test load for the 85 BTHP was seated to 2.650. This will chamber easily in my Remington's which have long throats but will not chamber in my Tikka or Browning X bolt.

Agree 100%. Those "book numbers" are simply just that and was the measurement obtained with that particular bullet and chamber at that testing. Other than mag. length info I never pay attention to those numbers.

 

[Dave M.]

First thing I do before I load a bullet I haven't used before in a specific rifle is measure the base to ogive of a least three bullets in a given lot then use the longest as my starting point to work up a seating depth. I use a Frankfort Arsenal type tool for this purpose.

I have learned that the book value doesn't always work for a given rifle / bullet combo. For example, Sierra list the maximum COL for the 243 Win as 2.710. Their test load for the 85 BTHP was seated to 2.650. This will chamber easily in my Remington's which have long throats but will not chamber in my Tikka or Browning X bolt.

^^^^^^ BINGO

 

[7887mm08]

Well, i guess from the replies to this it appears everyone thinks i am using book coal. That is not true!
I am just trying to point out the fact that the book coal for a given bullet and the ACTUAL max coal for this bullet in my gun are relatively close (.015"). I have with other rifles seen as much as .100". I look at book coal just to see what the jump would be if i had to use that coal because of mag length.
Thanks

 

[williepete]

So i decided im going to work up some loads on my rem788 in 222, want something different.
I have the sinclair cartridge length tool. Bullet im going to try is the speer 52 hp varmint.
Using the tool (which is a rod with 2 stops) it comes out to a max coal of 2.145" Book coal is 2.130"
Is it really possible that my chamber is that short?"
All other guns and calibers that i have used this method on were miles apart. Thanks and Happy New Year!

The Sinclair tool as you know just measures the chamber length
I use it all the time and yes it is possible that your chamber is that short.
Play it safe and trim your brass to the book 2.130 if you let the brass get longer and have a carbon ring
you risk the chance of over pressure when the carbon ring wont let the case mouth expand
properly. just my 2 cents happy new year all.

 

[Mark611]

You might try another overall length gage to confirm your measurement, I use the Hornady gage with a modified case, I'll check the measurement until I see consistent numbers JMO,

 

[dellet]

Well, i guess from the replies to this it appears everyone thinks i am using book coal. That is not true!
I am just trying to point out the fact that the book coal for a given bullet and the ACTUAL max coal for this bullet in my gun are relatively close (.015"). I have with other rifles seen as much as .100". I look at book coal just to see what the jump would be if i had to use that coal because of mag length.
Thanks

What you have likely found, is a bullet shaped very closely to what was used when the chamber was designed. Or just the opposite, a bullet designed for the cartridge.