Question on .223 case length

[Harbinger]

Gents,

I'm trimming a huge box of once-fired .223 and finding that many of the commercial cases are well below the standard 'trim-to' length for .223 (1.750). Nearly ALL the Radway, Lake City and WCC needs a good trim, but for the most part, the FC and R-P stuff has been at 1.74 or below (lowest I saw was 1.70).

I realize that if I'm loading for accuracy or need a good crimp, I need to separate by length. My question is: what is the 'minimum' case length allowable for .223 or 5.56? These 'short' rounds cycled were obviously fired successfully, so they may have been even SHORTER before firing and resizing.

Thanks in advance,

Mike

[J-cat]

Trim length has nothing to do with accuracy. The round headspaces off the shoulder. You don't need to crimp rifle ammo. Just clean off all the carbon from the inside of the neck, remove any residual sizing lube, and use .002" of neck tension on the bullet.

[Harbinger]

Thanks for responding, J-cat.

Should I not crimp... even if I want to avoid set-back in a semi-auto? Last time I loaded, I did an extremely light crimp. It was JUST enough to avoid set-back, from what I could tell.

Mike

Trim length has nothing to do with accuracy. The round headspaces off the shoulder. You don't need to crimp rifle ammo. Just clean off all the carbon from the inside of the neck, remove any residual sizing lube, and use .002" of neck tension on the bullet.

[-hanko]

Gents,

I'm trimming a huge box of once-fired .223 and finding that many of the commercial cases are well below the standard 'trim-to' length for .223 (1.750). Nearly ALL the Radway, Lake City and WCC needs a good trim, but for the most part, the FC and R-P stuff has been at 1.74 or below (lowest I saw was 1.70).

I realize that if I'm loading for accuracy or need a good crimp, I need to separate by length. My question is: what is the 'minimum' case length allowable for .223 or 5.56? These 'short' rounds cycled were obviously fired successfully, so they may have been even SHORTER before firing and resizing.

Thanks in advance,

Mike

Are your measuring after re-sizing or before?? Measure after re-sizing and trim as required.

-hanko

[Harbinger]

This is all after resizing. Some of the rounds were very short. So, in my 'trimmed' bin, I now have a bunch of 1.750 rounds and some that fall between 1.700 and 1.754.

I was just wondering if that's an issue, beyond crimping consistency and accuracy (which seems to not be a problem, according to J-cat).

Mike

Are your measuring after re-sizing or before?? Measure after re-sizing and trim as required.

-hanko

[jandmtv]

Just set your trimmer to 1.750" and trim them all, the cases that are shorter, don't worry about it, they will stretch out on the next reloading.

If loading for accuracy, you should make sure all the brass has the same head stamp, and all from the same lot.

[J-cat]

Thanks for responding, J-cat.

Should I not crimp... even if I want to avoid set-back in a semi-auto? Last time I loaded, I did an extremely light crimp. It was JUST enough to avoid set-back, from what I could tell.

Mike

Crimp does not prevent setback in self-loaders. Bullets are retained by case tension alone. There is not one rifle on the market where the bullet strikes the feedramp on the way to the chamber. The bullets usually deflect off the side of the chamber on the way in. This impact is indirect and should not set back a correctly assembled round.

What causes setback is poor handloading practices. For example, people leave carbon residue in the neck. It acts like lube between the bullet and the case. You want metal on metal contact there. Also, people leave lube in the neck after sizing the case. Lube is necessary when using an expander ball in the neck. Tumbling does not remove all the lube. You should use brake cleaner on a q-tip or something to make sure all lube is gone from the neck.

I use a Lee Collet Neck Die with a Redding Body Die that does not require any lube in the neck. I also run a bronse brush chucked in a drill to remove all the carbon. I end up with a "like new" neck with .002" tension on the bullet and (believe it or not) this is enough to keep the bullet in place without crimping.

Crimping without a cannelure can and often does buckle the case just behind the shoulder
and causes most instances of "stuck case."

[Harbinger]

The primary reason I am worried about setback is because I've actually seen it with factory Winchester 40gr .223 varmint rounds. The crimped/sharp nature of their proprietary 40gr hollow-points makes them prone to get caught on feed ramps and mag lips. This happened on two SU16 rifles and one 20" AR15.

It sounds like, from a case length perspective, I have nothing to worry about.

Mike

[ar15barrels]

Crimp does not prevent setback in self-loaders. Bullets are retained by case tension alone. There is not one rifle on the market where the bullet strikes the feedramp on the way to the chamber. The bullets usually deflect off the side of the chamber on the way in. This impact is indirect and should not set back a correctly assembled round.

I would disagree with much of this.
First, crimping into a cannelure is an excellent method to eliminate setback during feeding.
Look at most AR feedramps and you will find evidence of copper, not brass.
The copper comes from the bullet striking the feedramp during feeding.
This is normal and also the reason that some bullets have cannelures.

[J-cat]

But not from the bullet tip directly. The bullet hits at an oblique angle to the feedramp, so the top side of the bullet rubs off, not the pointy tip.

Second, in my testing, crimping did absolutely nothing for preventing setback. The cannelure does not have sharp edges that can catch the case mouth. The case mouth just rides out of the cannelure as the bullet gets pushed in.

Crimping a POS round results in nothing better than a POS round.

[bruceflinch]

Now to throw in another variable.... for accuracy in a bolt gun. bullet seating depth is very important. Seating the bullet as shallow as possible so the bullet is chambered just as close to the lands & grooves as possible to eliminate "bulllet jump". Like about .00010 of an inch +or- .

[bohoki]

hmm is the origional poster weighing each bullet?

as to crimp

i dont think it is needed bullets slide in the chamber if they nosedive they cause a jam and you probably wont shoot that one without checking it

the possiblity of the bullet being slightly skewed in the case would only be a problem with light bullets like 50gn and less that have small bearing areas

[J-cat]

Now to throw in another variable.... for accuracy in a bolt gun. bullet seating depth is very important. Seating the bullet as shallow as possible so the bullet is chambered just as close to the lands & grooves as possible to eliminate "bulllet jump". Like about .00010 of an inch +or- .

You won't get anywhere near the throat when loading mag-length ammo. When single feeding, bullet setback is a non-issue.

[diginit]

i noticed that in my SU-16, the bullet has 2 marks from the feed ramp. ALWAYS. This includs rem factory and military ammo at 2245 to 2255. I'm losding a 2250 OAL with 55 gr sierra bullets. WTF? Would Winchesters' suggested OAL of 2200 miss the ramp? Seems pretty short to me.