Reloading 223 Remington

[Recumbent]

I'm working up some test loads for my new model 12F/TR 223 remington.
Really weird but the 77 gr. Sierra Matchkings have a COL of 2.260" and the 80 Sierra Mactchkings have
a COL of 2.550" That's a big difference. I thought maybe a misprint but not the case, I checked 3 different loading manuals and also looked on line all
say 2.550".

With the 80 grainers seated at 2.550 the bolt won't close all the way in my rifle, so I think I am going to seat them
until it closes with no marks on the bullet.

What do you think??
Bob

[SSChameleon]

Check if there is a minimum COL. When pushing the bullet deeper and that close to the lands be sure to watch for pressure indicators.

[dfrosch]

Yep. The deeper you seat it, the higher your pressures.

I would get a Stoney Point(Hornady now) OAL gauge and find out how deep you need to seat them. This will make sure that you're not jammed. Probably need to back off on the powder charge and work up.

2.260 is the standard OAL for most bullets. Your barrel isn't throated for the 80s.

[darkker]

Well, not really.
Unless you REALLY go deep, seating deeper will lower your pressure. You need to do a rather significant change to seriously affect the burning rate. What you will do, is allow more time for gas bleed-off before the bullet engraves; meaning lower operational pressure.

Also don't put much stock in "Signs", unless you believe Jesus likes appearing in toast. All they can tell you is whether or not you reached your brass' yield point, which is generally around 75,000 psi.

Here is a chart done on depth and pressure.

[Recumbent]

I made up a dummy round put a 80 grain bullet in it and chambered it. It measured 2.440 So I loaded up 5 rounds seated to 2.400 to test.
Thanks for the replies.

[dfrosch]

Well, not really.
Unless you REALLY go deep, seating deeper will lower your pressure. You need to do a rather significant change to seriously affect the burning rate. What you will do, is allow more time for gas bleed-off before the bullet engraves; meaning lower operational pressure.

Also don't put much stock in "Signs", unless you believe Jesus likes appearing in toast. All they can tell you is whether or not you reached your brass' yield point, which is generally around 75,000 psi.

Here is a chart done on depth and pressure.

I really think Dr. Brownell was thinking about the other end of the bullet here. He took a 30-06 case, which has a lot of extra capacity, and loaded a 150 grain round nose with IMR 4064. He changed his seating depth by almost .450", so he had to have plenty of room in that case. I believe this experiment was about long throats, kinda like what Roy Weatherby did.

Loading an 80 grain SMK in a 223 is going to be a little different. You're going to use a relatively slow burning powder and you're probably going to use all of your case capacity. I load a 77 grain SMK over 24 grains of Varget at about 2.32" OAL, just to keep a few thousandths off the lands. This is a compressed load. I would argue that I am already near the bottom of that curve.

And, if I see shiny spots where the brass flowed into the ejector hole, well...

[darkker]

Well played on the pic!

I agree that in any given application there is an exception, but the principal still holds. Seating deeper allows more blow-by, which is what Weatherby was after with the long throats. More gas bypass allows more bleed off, and a safety factor that way.
A compressed load is another animal. Powders will begin to get grumpy at some point, so they will no longer act in as linear and predictable fashion; so not quite the same discussion.

My point about "signs" is that it isn't close to rated cartridge pressure, and isn't consistent. Using that as your stopping point for safe pressures, is a bit like listening to your lifters hammer to decide if you need to change your oil. Lack of lubrication will cause then to clatter, but waiting that long isn't a great idea of you want the motor to last.
I used to think that my brass, primers, and extraction were really good at letting me know where pressure was. Then we began testing with a Pressure Trace, and I quickly learned I really didn't know nearly what I thought I did.
If you match book Velocity you may already be over pressure, when you exceed it you really exceeded SAAMI pressure.
Here is an example


High pressure? Nope, just another soft-headed Federal POS case. This one actually came apart in a rifle with the pressure trace, and went across the chrono.
Below, the case on the right, actually was a run away, that hit 75,000 psi at two different points when the bullet was still in the barrel.

[Texas10]

This might answer some questions you have about COL and the 80 g SMK.
http://www.savageshooters.com/showth...in-224-changed

[Fotheringill]

I have the same rifle as the OP.

"With the 80 grainers seated at 2.550 the bolt won't close all the way in my rifle, so I think I am going to seat them
until it closes with no marks on the bullet."

I have the same issue and the longest I can get in and close the bolt without issues is a 73gr Berger. Don't worry about OAL since the rifle has no magazine. Shorter is ok and so is longer. My measurement with the 73's base to ogive for seating purposes is 1.9455".

When you are loading, listen for the crunch while seating.

[Scott Evans]

Reloading manuals (USA) use SAAMI specs, procedures, and data, thus the 2.260" max OAL for majority of 223 data. One source for non-SAAMI data for 223/5.56 is Western Powders, which also has a section for CIP/NATO, and 'custom long throat' (heavy 75g+ bullets). You can learn a few things by studying the differences.