Hi everyone,

I've just taken up loading the .223 after 5 years of success with the .308. Since I'm loading for autoloaders, I've always used the Lee FCD on my .308, and extensive testing has shown that it does really improve my accuracy. This is, I'm sure, due to the extremely consistent velocities it gives me. For example, with 10 rounds tested out of my AR-10 with both 150gr FMJ and SST, the most accurate load averaged 2763fps, with the highest number being 2765, and the lowest 2761! I never had any pressure signs when load testing in .308, even going up to max loads with military brass.


With .223 out of my go-to carbine, I was getting some serious primer cratering and flattening with max loads. I know this means I should back off, but I was wondering whether applying too much crimp could be causing this; essentially making an otherwise-fine load experience pressure signs.


This concerns be also because I like to crimp on the heavy side. I don't apply so much that it compresses the bullet's jacket or core, but I have found the technique recommended online of having the die only tight enough so that the petals move a little to be insufficient. I have found on both .308 and now .224, that I have to get the petals to come together completely to notice any crimp on the case mouth. Also, before anyone asks, I am measuring this with buckets with a cannelure. I know the practice is still useful on bullets without it, but the crimp ring does not show up on it.


Thanks in advance for your help!

Yes, ANY excessive crimp can lead to over-pressure.

Was the load safe without crimping? If so, and you still want to crimp, back off the FCD until it barely closes and load 5. Incrementally increase the crimp until you have the FCD set to it's max capable crimp (or the level you see the pressure sign now) and load 5 at each increment. Mark the cases somehow for crimp ID.

Shoot the rounds, watching for pressure signs. Stop immediately at the first sign and determine what crimp stage it was. That will be your over-max; the step below will be your max crimp.

Need details of load:

What brand/model of primer?

Which powder and how much?

Good call! I use H4894, since it's the powder that works best for me on .308, and consequently I have a ton of it. I load 55gr Hornady FMJ and 55gr Sierra SBT (spitzer soft point boat tail). I am all about 55gr, because the barrel twist on my AR-180 won't stabilize anything heavier, and I want all my guns to be able to shoot my loads well.

 

For both projectiles, I start at 25gr of H4895, and max out at 26gr, which was the load that was extremely accurate but gave me pressure signs. I use a standard CCI small rifle primer and Lake City brass.

There is probably nothing wrong with the load. But don't use CCI standard small rifle primers in 5.56 loads. their cups are too thin and show premature pressure signs.

Either use CCI BR4 or Remington 7-1/2. Both have thicker cups.

Spot on, the CCI 400 can't handle higher pressures of 5.56*45 loads.

I will add to the list of primers: CCI 450, CCI 41, and KVB556M.

I agree with dryflash3.

What ever crimp that is applied so quickly and easily overcome from the pressure rise I doubt that it would make a significant difference in pressure. But when you are pushing maximum levels any small increase can show.

The way you describe using your FCD is right in line with normal practice. You are simply applying a maximum crimp. When the fingers completely close it's at max.

If you were crimping oversize lead bullets then yes you can crush the bullet within the case neck crimping for max effect.

I've seen CCI-400s and CCI-450s as well as other small rifle primers show false signs of over or high pressure in ARs. Primer reading is not very accurate to start with but it seem even less productive of usable results with small rifle.

Motor

What about Tula?  I just made 10 test loads of TAC 5.56x45 starting loads..................

 

Thanks a lot; I figure I'll try one of these harder primers. It struck me as odd that my top-quality M4, chambered in 5.56, would show problematic pressure signs on loads within the .223 pressure range. This also fits very well from what I saw; although the primers showed pressure signs, the brass showed none at all. Not only were their no bent rims or smeared head stamps, there were not even extractor or enector marks! I often get those with factory ammo.

 

I talked to CCI, and they told me to stay away from the number 41 military primers, because they deliver a magnum charge, and the load data off of which I'm working is for standard-pressure primers. Any recommendations on which is harder: CCI BR4, Remington 7.5, etc.? I am leery of Tula/Wolf primers, as I don't trust those damn Russians on anything, least of all firearms and ammunition. After experiencing how unreliable three different Arsenal Saiga AKs were compared to my AR-10 and M4 (they were pretty good, but did malfunction occasionally, which my very hard-run ARs literally NEVER have), I would much rather pay a premium to buy American.

I agree.  (though it sounds like it might just be a soft primer issue).

A crimp is going to be one of the last things to cause an overpressure situation.

You can shoot oversized bullets through bores with no issues, a crimp is easily overcome. If you suspect pressure problems, back off the load.

In my experience, the BR4 primers are not worth the extra money unless

shooting benchrest precision.

The CCI magnums (#41 and 450) have a thicker cup, that's why they are

generally better at handling higher pressure. Just back your load off a

half grain and work back up.

Tula/Wolf KVB556M are magnums, thicker cup, and have all gone

pop in the 2K I've used. They seem to be slightly wider diameter,

which I find desireable in high preasure .223/5.56*45 loads.

The Rem 7 1/2 are considered magnum primers.

So for me, running H335 ball powder and 55gr fmj Hornady bullets,

CCI 450 are number 1, Tula/Wolf KVB556M second, and CVI #41

and Rem 7 1/2 tied for third choice.

At max loads with primers cratering, what was the velocity you were getting?

That's the thing, I don't know my velocities, because there is literally no range that either rents, or even is set up for one to use chronographs in the whole northern Virginia area (and forget about DC, into the big government belly of which I have to commute for work each day). I actuallity found that the max load of 26gr of H4895 also gave me the best accuracy (sub-MOA out of my BCM ultralight midlength upper with iron sights), and it was only a bonus that this load was also the fastest. My philosophy on loading cartridges of more marginal effectiveness like the .223 or any duty pistol round, is to get as much velocity as can be attained with good accuracy and safe pressure levels. This is very different than how I feel regarding full-power rifle cartridges like the .308, where I consider them to have ample power to spare, and to be just fine with more moderate loads.

 

Man, and I thought the hemp curtain around Chapel Hill, NC where I grew up was oppressive to real Americans and our firearms; northern VA is even worse!

I also agree about a thicker cupped primer.

Double check your trimmed case length as well. If it is to long... in could be constricting your bullets ability to enter the bore as normal.

And producing pressure signs as well.... never hurts to double check.

Good suggestion there, thank you! I trim, chamfer, and measure each and every case I prep for loading, so that is one variable I have eliminated. It is very edifying and bears repeating, however, for all reloaders.

 

Nothing wrong with CCI 400 primers....

Ive run as much as 25.5gr of H335 behind a Hornady 55gr FMJBT with no issues with the 400s.

Its the Remington 6 1/2's that you want to avoid.

Using cci 400's i start to show pressure signs at 25gr of imr4895 with a hornady 55fmj, if i switch to fed 205's i won't see flat primers until 26 gr or so, 400's will work if you start and stay with the powder you worked up too with it, but if you switch to 400's from another max load you worked up from another primer watch out because they will pierce a lot easier than other primers.

55 grains in a .308??

That is extremely light.
Maybe 155 grain????

Thanks for all your help; I have brought my experiment to a very successful conclusion!

As it turns out, switching out the primers for the CCI BR4 with the thicker/harder cups worked out perfectly. I worked up another set of loads, and all the way up to the max (26gr of H4895) there were absolutely no pressure signs, and the fastest load still showed the best accuracy.