Max COAL questions

[xxtavixx]

hello everyone,

I was hoping to get some input on a few questions, after hours of looking at various threads and some semi conflicting one another I am in some ways more confused than when I started.

I'm new to reloading. I decided yesterday to load up some rounds for my 270 using 130g Nosler Partitions. I wanted to try to see if the gun liked the powders I have sitting around not being used for anything else so I loaded up some IMR 4895, IMR 4350 and some RL22 (which I bought to try in the 7mag). I set my dies up and noticed there was a little variation in the over all lengh. Nosler COAL max was 3.340, which is where I set my die up.

Since this was my first time loading for the 270 I checked every round that was produced and I noticed some would end up at 3.34, and some would be at 3.32 or 3.33. I read a few threads and discovered that the way I have been measuring COAL is not correct...who'd have thunk that measuring the total length would not be the "cartridge over all length".

A buddy loaded some with his 30/30 and I noticed the same variation, but to a larger degree. Set up after crimping to be at 2.550 (which was what was called for in the book) the cannelure was barely in the case, so we set them a bit deeper. Some would end up a total length of 2.440, and one came out around 2.420. I imagine that part of this may be due to the variation in the bullets, since he using a much less reputable bullet.

So now I am nervous. Am I just being ridiculous in lieu of being newer to reloading, or should I buy a COAL measuring tool and see where they end up?

Thanks for any help/advice!

 

[Engineering101]

No you don't need to measure COAL off the bullet ogive. If you did you would find your bullets closer to the same length than if your measurement includes the tip. Also max COAL as listed by the manufacturers is nothing more than a reference that tells you how they setup their loads. That is almost always the length that you DO NOT want to use for your ammo. Chances are your ammo will be more accurate if you seat the bullets closer to the start of the lands. The way to do this is to make some tooling for each of the rifles for which you load. The tooling is a fire formed case that has had the neck split with a hacksaw (and burrs removed with a file inside and out). This allows you to put a bullet in the case and chamber the round. Take the round out of the chamber and measure it for overall length. Do this with several samples of the bullet to get the most consistent number. The resulting number is the overall cartridge length that will just fit in your chamber with the bullet just touching the lands. Many of my loads are most accurate about 0.005" off the lands so I usually start there. I may end up putting the bullet 0.020" or 0.050" off to get best accuracy. You also have to consider magazine length if that is a concern. The trick with getting this tooling to work is relatively stiff neck tension on the bullet. You may have to resize your tooling (the case with the split neck) to tighten it up. You should be able to adjust the bullet seating depth by hand but just barely. I do this for every bullet I load. You can also use the tooling to setup your seating die. Good luck.

 

[243winxb]

What press and dies are you using? Single stage variation is .005" and a progressive is .010" maximums. This is when using good bullets, not FMJ.

The range of COL is listed at SAAMI | Sporting Arms and Ammunition Manufacturers' Institute for each cartridge.

 

[xxtavixx]

Thanks everyone.

I am using an old Lyman Turret press, and using new RCBS dies. I am curious how consistent I would be if I measured off the ogive.

Engineering101, I had actually been reading about doing that exact same thing. I am debating pulling the bullets and reseating if they should be longer. Seems like a lot of people set at either .02, .01 or .005 off.

 

[FEENIX]

Find the best compromise between COAL and CBTO (you'll need a comparator or similar tool to do so), and what your magazine allows; the following should help you better understand the concept...

Effects of COAL and CBTO | Part 1 | Berger Bullets Blog

Effects of COAL and CBTO | Part 2 | Berger Bullets Blog

 

[243winxb]

A Lee dead length seating die will remove slop for the press. The die is in contact with the shell holder when seating. It acts as a stop , controlling COL better.

Redding reloading gives a tip on there custom seater, adjust so die makes contact with the shell holder, to make COL variations smaller.

This can NOT be done with RCBS, because the seat die has a built in crimper.

Nosler has listed a COL of 3.320"

 

[FEENIX]

Nosler has listed a COL of 3.320"

Must be typo as SAAMI's is 3.34" in all on my reloading manuals including my Nosler 6th ed. Having said that, my COAL for 150 NBT is 3.43".

 

[243winxb]

The 3.340" is just a SAAMI maximum standard. Nothing more.

 

[xxtavixx]

Feenix, those are some GREAT reads. Really got me thinking.

So by COAL standards, I am OK. But I am potentially giving up some accuracy until I figure out where my lands are and then measure CBTO. Seems like the easiest way to do if you are using the same bullet is the process described earlier, which basically seats the bullet against the lands. Once you have that total length, you seat the bullet just a .010 (or whatever desired distance) back further than the round you chambered. Using this method, is there really a point in getting something like the Hornady Chamber all tool?

Working from that logic, would I be best to shoot the rounds I have already loaded to see what powder and what weight shoots best with current COAL, and then start to work on my distance to the lands?

 

[xxtavixx]

No you don't need to measure COAL off the bullet ogive. If you did you would find your bullets closer to the same length than if your measurement includes the tip. Also max COAL as listed by the manufacturers is nothing more than a reference that tells you how they setup their loads. That is almost always the length that you DO NOT want to use for your ammo. Chances are your ammo will be more accurate if you seat the bullets closer to the start of the lands. The way to do this is to make some tooling for each of the rifles for which you load. The tooling is a fire formed case that has had the neck split with a hacksaw (and burrs removed with a file inside and out). This allows you to put a bullet in the case and chamber the round. Take the round out of the chamber and measure it for overall length. Do this with several samples of the bullet to get the most consistent number. The resulting number is the overall cartridge length that will just fit in your chamber with the bullet just touching the lands. Many of my loads are most accurate about 0.005" off the lands so I usually start there. I may end up putting the bullet 0.020" or 0.050" off to get best accuracy. You also have to consider magazine length if that is a concern. The trick with getting this tooling to work is relatively stiff neck tension on the bullet. You may have to resize your tooling (the case with the split neck) to tighten it up. You should be able to adjust the bullet seating depth by hand but just barely. I do this for every bullet I load. You can also use the tooling to setup your seating die. Good luck.

So question about doing this. If you do this how are you measuring consistently? Based off of reading the two articles from berger bullets The actual bullet link that can vary quite a bit, and you were not measuring at the ogive because of that. So it seems like this is where you need a tool to constantly measure the ogive.

 

[243winxb]

some would end up at 3.34, and some would be at 3.32 or 3.33

Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Seating Depth Variations - Powered by Kayako Help Desk Software

Trying to get close to the rifling in a factory chamber is mostly over rated and applys more to custom benchrest rifles.

Go shoot what you have already loaded.

 

[N2TRKYS]

A Lee dead length seating die will remove slop for the press. The die is in contact with the shell holder when seating. It acts as a stop , controlling COL better.

Redding reloading gives a tip on there custom seater, adjust so die makes contact with the shell holder, to make COL variations smaller.

This can NOT be done with RCBS, because the seat die has a built in crimper.

Nosler has listed a COL of 3.320"

The 3.320" COL is their tested COL. 3.340" is the max COL.

 

[N2TRKYS]

I always load to Nosler's tested COL and have been spot on in 5 different rifles and calibers. I notice some differences in COL, but not enough to affect my accuracy. Heck, all of the bullets don't weigh the same, either.

 

[LaHunter]

Assuming you are not 'magazine limited', Cartridge Overall Length is not a very useful measurement for precision handloading.
As you are finding, there can be a lot of variance in this measurement, and it really provides no useful info as long as you are not limited by overall cartridge length.

The Cartridge Base To Ogive (CBTO) measurement is what you need to be measuring. This is a very useful and important measurement. With quality tools, a solid brass prep process, and high quality bullets you should be able to stay within +/- .002" in your CBTO measurement.
Hornady makes a tool that you can use with your digital caliper to get this measurement.

This is the measurement that you need to use when determining bullet seating depth.

Good Luck