What length do you trim your .223 for AR use

[CozMoDan]

I have seen in several different loading manuals stating 1.740 as their COL. Also I know one would chamfer after trimming but do you chamfer otherwise, i.e. each time you reload cartridge?
The Coz

 

[Red Six Bravo]

1.750 is what I trimm mine too. This is also checked in a Dillion case gauge. See this link for some good technical information.

http://www.6mmbr.com/223Rem.html

 

[Walkalong]

1.750 for me as well. Bolt, auto, doesn't matter.

Deburr and chamfer and trimming, but not every time you reload it. Even if you do have not trimmed, one deburring and chamfering can help smooth loading.

 

[jmstevens2]

Are we talking .223 or 5.56 mm? Isn't 5.56 length 1.77" ? There is a difference between the two.

 

[cfullgraf]

My Lee trimmer trims a thousandth or two above 1.750" but I would consider 1.750" as the minimum.

I just obtained a WFT trimmer to try. It will be set for the plus side of 1.750".

The only time I would see the need to trim shorter would be if you are using an RCBS X-die. The instructions for the X-die say to trim shorter than standard before using the X-die.

 

[steve4102]

Are we talking .223 or 5.56 mm? Isn't 5.56 length 1.77" ? There is a difference between the two.

Interesting, where did you find this info? Everything I can find says that the 5.56 Nato has a max case length identical to the 223, 1.760 and a "trim to" of 1.750.

 

[DaveInFloweryBranchGA]

I FL resize all my .223 brass, then trim it to 1.740" and reload it. Once the reload has been fired, I FL resize using an RCBS X-die. Haven't had to trim any of the brass done this way a second time.

Best Regards,

Dave

 

[steve4102]

I FL resize all my .223 brass, then trim it to 1.740" and reload it. Once the reload has been fired, I FL resize using an RCBS X-die.

This may be where the OP got the "trim to " of 1.740. The "trim to" when using the "X" die for the first time is .010 shorter than standard "trim to".

 

[wingman]

I set my trimmer for 1.752.

 

[BADUNAME37]

I typically trim all my brass halfway between the trim-to length and the maximum length. That way, the cases are either in the middle or anywhere up to maximum, I don't mind that small a difference. I can mic several hundred cases in less than 30 minutes and sort them, maximum or over get trimmed, between mid-way and max don't get trimmed.

I used to just throw them all through the trimmer but then realized I can operate the caliper faster than placing the case in a collette and going through the trim motions for those cases which don't need trimming!

 

[243winxb]

I chamfer only after trimming, when loading a boatail bullet. If a flat base gives you a problem, then maybe you dont have enough chamfer to start with. Brass trim length is usable from 1.760" to 1.730" Standard trim to length is 1.750" for the 223/5.56

 

[cfullgraf]

I used to just throw them all through the trimmer but then realized I can operate the caliper faster than placing the case in a collette and going through the trim motions for those cases which don't need trimming!

I do the same, but have made a "Go-No-Go" gauge for case length. Those that don't fit the gauge get trimmed.

With so many inexpensive calipers on the market these days, my gauges are a luxury. I just don't like handling precision measuring tools more than necessary.

 

[capreppy]

I trim to 1.750 and then chamfer/debur after.

 

[CHALK22]

^what he said^

 

[Waywatcher]

^Yup; trim to 1.750, then chamfer and deburr.

I use a precision mic to bump my shoulder back ONLY 0.003 to 0.005 for my AR, and my brass grows very, very slowly. (This is also in a .223 chamber AR.)

I have a batch of LC brass that has been fired 3 times, it was trimmed only once, when it was brand new--unfired. I measure length after sizing, so this brass has been sized four times. I was paranoid, so I measured every single one and they were all under 1.758, and 90% of them were 1.752.

 

[Gik-tal]

I keep mine at 1.759"

 

[HJ857]

I trim to 1.754, but only trim brass that's over 1.760. I'll allow brass from 1.748 to 1.760.

 

[CozMoDan]

Red Six, lot of info on that link, as you said.
Thanks
The Coz.

 

[GLOOB]

I trim mine to 1.748". I retrim when it gets beyond 1.756" or so. But I don't shoot much .223. If I did, I'd soon get tired of trimming so often. I chamfer only after trimming.

 

[mboylan]

Are we talking .223 or 5.56 mm? Isn't 5.56 length 1.77" ? There is a difference between the two.

Ramshot is the only manual that I know of that has 5.56 data. .223 and 5.56 case dimensions are published as identical. Chamber dimensions are different. 5.56 chambers have a longer leade to handle the higher pressure.

 

[Clark]

Most guys look in a load book and read the max case length and the trim length.

I have measured the length of the chamber neck to breech face, and subtracted off the amount that the case shoulder is pushed back relative to the chamber shoulder to breech face dimension. That is the real max case length, and it varies for each piece of brass and chamber. This is because the firing pin will push the case forward.

Choosing a trim length is more subjective.
I came up with a process to trim brass quickly in the mill, that also chamfered inside and outside the neck.

Finally, I elected to never trim 223 brass again.