Case length-223,5.56

[jrd541280]

Polished and re-sized about 2,000 various brand 223, 5.56 range brass now and am amazed at the various case lengths. I set my trimmer at 1.755" (mid range) and find myself trimming 10 to 30 thousandths off all lc military brass. And that fc brass is minimum 5 to 20 thousandths short of that. You guys that do a lot of this run into the same thing?

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[ageingstudent]

Yes and some brands come shorter. I usually trim to 1.747ish the first time so I don't have to trim again for a couple cycles. An AR can work you to death trimming all that brass every firing.

 

[v0lcom13sn0w]

i trim to 1.750 but sometimes shoot them even after they fail my case length gauge anyway. its a pain to trim every or even everyother time

 

[ChiefStealth]

Just went through 500 mixed, once-fired. Trimmer is at 1.752. About half needed trim. Almost all the LC needed trim. About half were already shorter than the trimmer. Some were quite a bit short. I didn't really notice what brand, but they were all .223 brass. Not 5.56 brass.

 

[jrd541280]

After realizing so much variance in the case lengths I also seperated the new range brass from what I had previously trimmed. So as you said hopefully wouldn't have to trim again for a few cycles. So far, haven't had to in either my bolt gun or ar. but still wondering why so much difference in once fired case length in the first place? Lc military is way long on saami specs and fc is way short of them. Again, polished and re-sized before measuring to take chamber dimensions out of the equation. Appreciate all input.

 

[v0lcom13sn0w]

another thing i do is i separate all crimped and de crimped brass so i dont de crimp it twice. saves time.


3 way rcbs case trimmer is the big time/hand saver

 

[Member 5605]

I trim every time. It's nothing to run it through the Frankfort Arsenal prep center. I don't run in an AR either, a bolt rifle but consistency is key.

 

[v0lcom13sn0w]

I trim every time. It's nothing to run it through the Frankfort Arsenal prep center. I don't run in an AR either, a bolt rifle but consistency is key.

over achiever

 

[Member 5605]

over achiever

Slacker...

 

[v0lcom13sn0w]

Slacker...

lol u got me. i walked right into that ha ha

 

[Caveman Jim]

So how short is too short? I am sorting about 500 right now and they range from 1.734 to 1.757. I laid them all out from longest to shortest so I don't have to measure them again if there are some that should be discarded.

 

[John Gault]

Remember, anything too short can be reborn as 300 blackout casings.. assuming they're not plain worn out

 

[Caveman Jim]

Remember, anything too short can be reborn as 300 blackout casings.. assuming they're not plain worn out

True that but what is the deciding factor?

 

[Member 5605]

True that but what is the deciding factor?

IMO...

Length depends if you are crimping or not. Consistent crimp means you want the necks to be the same length. Neck length also has to do with neck tension.

I do not crimp so if I have something short (1.730-1.740) I shoot it and use it like normal. Adventually the neck will grow.

1.750" is the trim to length, but many also trim down to 1.740". 1.734" isn't too far off of that trim length.

Assuming there is no head separation and no head growth beyond what's bumpable...I say keep using them. No harm. They will grow next use

 

[Silver Hand]

i trim to 1.750 but sometimes shoot them even after they fail my case length gauge anyway. its a pain to trim every or even everyother time

Shooting long brass is a bad Idea doing so in a dirty gun is a worse Idea.

Want better accuracy
You should size your brass - [choose the quantity for best accuracy] - before you trim it, that makes the outside of the cases equal. Then separate them by head stamp to get close on the interior.
Now weigh each case and put them into lots.
Your pressure will be in controlled groups. Bench rest shooting will soon show what brand your rifle likes best.
Silver Hand

 

[Caveman Jim]

IMO...

Length depends if you are crimping or not. Consistent crimp means you want the necks to be the same length. Neck length also has to do with neck tension.

I do not crimp so if I have something short (1.730-1.740) I shoot it and use it like normal. Adventually the neck will grow.

1.750" is the trim to length, but many also trim down to 1.740". 1.734" isn't too far off of that trim length.

Assuming there is no head separation and no head growth beyond what's bumpable...I say keep using them. No harm. They will grow next use

Thanks for the clarification Dyg. I did some more searching on this to see what others have said.

"SAAMI min case length for the .223 is 1.730" is what was said on another forum as well as "YMMV"..... I think I'll save the brass that measures less than 1.740 for a future 300AAC practice project.

 

[Member 5605]

Thanks for the clarification Dyg. I did some more searching on this to see what others have said.

"SAAMI min case length for the .223 is 1.730" is what was said on another forum as well as "YMMV"..... I think I'll save the brass that measures less than 1.740 for a future 300AAC practice project.

Correct...
and SAAMI maximum 1.760", customary to trim .010-.020" of brass. As long as it's between 1.730-1.760" you are golden!

 

[Caveman Jim]

The 500 I have processed so far are ALL Federal & from what I've read that is a common trait, short.....
The PMC once fired by me are mostly 1.753-1.762..... They all have to be trimmed.
More work but it keeps me busy since it's raining out and I have become a fair weather fisherman....