Case Length and Bullet Seat Question

I am new to reloading and I have a question on case length. (Forgive me if this is a dumb question!). In the Lyman's 50th edition reloading manual, for .223 for example, it lists a trim to length of 1.750" for the cases.

If I have cases that are between 1.740"-1.745", and the COAL for a specific load is 2.250", am I still fine to seat the bullet to the 2.250" overall length?

In doing so it seems the bullet would be seated .010" less than if all the cases were all the proper length of 1.750". Am I supposed to adjust the COAL down accordingly for the length of the brass?

Thanks for your help, this has me confused!

Powerstroke said:

I am new to reloading and I have a question on case length. (Forgive me if this is a dumb question!). In the Lyman's 50th edition reloading manual, for .223 for example, it lists a trim to length of 1.750" for the cases.

If I have cases that are between 1.740"-1.745", and the COAL for a specific load is 2.250", am I still fine to seat the bullet to the 2.250" overall length?

In doing so it seems the bullet would be seated .010" less than if all the cases were all the proper length of 1.750". Am I supposed to adjust the COAL down accordingly for the length of the brass?

Thanks for your help, this has me confused!

Click to expand...

It can be a little confusing at first. Case length has no affect on COAL. The bullet slides into the case mouth, so when seated, there is a fixed distance between the shell holder and the seating stem of the bullet seater die. How are the bullet is seated is determined by the distance from the base of the case - not the neck.

To illustrate this, take a junk case and trim it back so it has just enough neck to hold the bullet. Seat a bullet into that case, then seat a bullet into one of your 1.740"-1.745" cases. The COAL will be the same (provided the bullets are the same).

For what it's worth, COAL is not very precise as normal variation in the bullet tip will affect the COAL measurement. You need to know the COAL to ensure the bullet will fit within a magazine, and it's a good place to start when developing a new cartridge load, but after that better to invest in a comparator gauge, and measure from the cartridge base to ogive (CBTO). The bullet ogive is far more consistent that the bullet tip (which is prone to small deformities).

Powerstroke said:

I am new to reloading and I have a question on case length. (Forgive me if this is a dumb question!). In the Lyman's 50th edition reloading manual, for .223 for example, it lists a trim to length of 1.750" for the cases.

If I have cases that are between 1.740"-1.745", and the COAL for a specific load is 2.250", am I still fine to seat the bullet to the 2.250" overall length?

In doing so it seems the bullet would be seated .010" less than if all the cases were all the proper length of 1.750". Am I supposed to adjust the COAL down accordingly for the length of the brass?

Thanks for your help, this has me confused!

Click to expand...

Not saying 1.740 is a safe case length for .223, but if it is, still load to recommended COAL. That way, the internal case volume stays the same.

If you seat the bullet 0.10" deeper, you will increase case pressure.

SAAMI case length specs are published as 1.74 inch minimum, not to exceed 1.76 inch maximum. You're within spec. Follow your manual's 2.25 inch OAL spec for bullet seating.

Good on you for paying attention to details, and questioning variations. That practice will serve you well. In this instance, you're fine OP.

Before doing too many rounds, I like to cycle a couple in the gun they will be fired from to make sure there are no problems.

My dad did some loads that were so long that the bullet contacted the lands so that I could not eject an unfired round without pulling the case and bullet apart. I discovered this when the range was made safe and I could not eject the round in my gun's chamber. A RSO stayed with my gun during the break and I had to clear the weapon by firing the round before they would let the range go hot again.

Now that I am loading my rounds and am still learning, I just take the time to check the first few rounds and spot check some for OAL as I seat the bullets.

Are you measring unsized or sized cases? That will affect the measurement.

If you are seating a cannulared bullet to a specific point in the cannular, C.O.L. will be effected by case length when you adjust the seating die. All subsequent rounds, however, will be the same depth.

outrider58 said:

Not saying 1.740 is a safe case length for .223, but if it is, still load to recommended COAL. That way, the internal case volume stays the same.

If you seat the bullet 0.10" deeper, you will increase case pressure.

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I thought that only happened when bullet weight was increased without adjusting the charge accordingly in the same rifle.
In a normal load with the bullet seated to just miss contact with the leade, pressure builds smoothly and evenly throughout the powder burning period and velocity will be "normal" for a particular rifle.
Seating the bullet to allow it to travel further before the leade is contacted permits the bullet to start and then allow the expanding gas more room at a higher rate to expand without resistance never reaching the same pressure or velocity of the first "normal" load.
Seating bullets towards the leade with the same load and all other things being the same can have the same effect but in reverse. Velocity and pressure increases especially higher if the bullet begins to contact the origin of the rifling without reducing the charge.
This is how you can maintain velocity in rifles with a worn leade, by seating the bullet closer to the leade without increasing the powder charge outside of published data. It may even have to be reduced if mixed lots of brass are being used.

Magnumite said:

Are you measring unsized or sized cases? That will affect the measurement.

If you are seating a cannulared bullet to a specific point in the cannular, C.O.L. will be effected by case length when you adjust the seating die. All subsequent rounds, however, will be the same depth.

Click to expand...

Measuring after sizing. What is the cannular? Sorry, I have not heard that term before.

Powerstroke said:

Measuring after sizing. What is the cannular? Sorry, I have not heard that term before.

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I don't mean to come off as a smart ass but the safest thing for you to do is to buy a reloading manual. The Lyman #50 is a good general loading manual which will explain all that you need to know about reloading.

That said, the cannelure is the serrated line made around the diameter of some bullets. Not all bullets have them. You can crimp the case mouth in the cannelure but you don't have to.

Some cases have a cannelure to keep bullets from backing into the case during recoil.

Powerstroke,
In addition to your Lyman manual, you can also get data from Hodgdon powder website, Accurate powder website, Ramshot powder website, Vihtavouri website, and Alliant website. Accurate powder has loads that they dont publish in their normal data for wildcats. They will answer emails and have been a big help to me with 45 Super and some Ackley improved load data