Neck length important?

[mousegunner]

I have some Speer .223 brass that i try to trim to .750 but some of it is actually shorter than this and others trim just right. This after full length resizing. This is once fired LEO brass out of M4s. I've used the LEO Win brass and it's very consistent and trims to .750.

Anywho I want to use this brass for 55 Hornady FMJs and get a good load for my carbine. Should I trim to under .750 to a point where all brass is the same size, separate the short ones or load all the same regardless of trim length? Yes I know if I had a Giraud I wouldnt have a problem but I have the RCBS trim pro. Thanks for looking.

 

[nicholst55]

I doubt that it will make any appreciable difference, as long as there isn't a huge difference. Those bullets wouldn't be my personal choice for an accuracy load.

 

[mousegunner]

For accuracy I have my AR NM service rifle and an AR match rifle, this is for plinking and some 3-gun. I have a boat load of 55 FMJ so I want to use them up but get as accurate as I can given the bullets, barrel, etc.

 

[Dusty Stevens]

Trim em all to the shortest one within reason and watch for carbon in front of the case mouth or youll get a crimp when you dont want it

 

[243winxb]

Max is 1.760" SAAMI . Minimum trim is -.030" or 1.730"

But shorter produces less neck tension. Watch for bullet movement on chambering.

I would just let it grow to maximum, then trim.

The bullet may leave the case mouth before powder starts to burn fully.

No crimp needed with good neck tension.

 

[NorCalMikie]

Don't trim till you know the EXACT MEASURED length of your chamber. May not have to trim for a long time.

 

[Texas10]

I find many new 223 brass is made to minimum length, sometimes shorter. I set my trimmer to mid range and if the brass is shorter or hasn't grown enough to get trimmed, no big deal. Watch for carbon buildup like Dusty advises. A carbon pinch can be quite entertaining on the firing line.

 

[T-shooter]

For accuracy I have my AR NM service rifle and an AR match rifle, this is for plinking and some 3-gun. I have a boat load of 55 FMJ so I want to use them up but get as accurate as I can given the bullets, barrel, etc.

A cheap plinking bullet I've had a lot better luck with is Hornady's 62 grain BTHP (lower right). The 69 grain Sierra's seem to be a little more accurate.

 

[mousegunner]

How's the 62 BTHP out of a 1-9 barrel?

 

[JMayo]

If you're not shooting competitions, as in seriously getting everything the same, don't worry with it.

 

[tenring]

How's the 62 BTHP out of a 1-9 barrel?

The Sierra 62 gr. shown above shoots well in my factory Savage .223.
If I don't know my chamber length, I trim .005-.010" under SAMMI.

Never heard of Speer .223 brass. Where did you find it?

 

[Ned Ludd]

I would trim as many as you can to the desired length, leaving the short ones as they are. Hopefully within a firing/resizing cycle or two, most of them will grow enough to trim at the desired length, assuming they're not short by more than a couple thousandths or so. I strongly doubt you will ever notice any difference between slightly short versus desired length cases in a carbine load.

BTW - if you're actually trimming to 0.750", I'd be shocked that some cases are too short to be trimmed .

 

[mousegunner]

The Sierra 62 gr. shown above shoots well in my factory Savage .223.
If I don't know my chamber length, I trim .005-.010" under SAMMI.

Never heard of Speer .223 brass. Where did you find it?

Range pick up from LEO range.

 

[mauser284]

Accuracy is about tuned ammo that is the best it can be for n=1. So that said no matter what precision and consistency is a must. That is why we do idiotically anal-retentive stuff like weight cases right out of the plastic box and size new brass. Unlike society were diversity and difference can at times be a good thing it is the scourge of accuracy in ballistics. You want all your brass, bullets, primers and charges to be as uniform and close to perfection that a human can attain! I would use those for plinking, varminting on non-critical situations like shooting fat ground hogs at the end of you driveway! LOL When I sort brass all the brass at both ends of the bell curve are turned into ammo for hunting or plinking only not fit for competition but still good for everything else.