The instructions for my RCBS X-Die say to trim brass to 0.02" under max length, which is 1.74" for 223 / 5.56mm brass. This seems a little short.

Is this the length that others are using with the X-Dies? How is it working out?

Thanks in advance.

Mike

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NRA Certified Pistol Inst.

I have used RCBS X-dies for 30-06, .308 Win, 260 Rem and 223 . I would recommend following the RCBS instructions. The cases will grow a little upon repeated firing to stabilize a little under the normal trim-to-length given in reloading manuals.

Trimming becomes a one time thing (yea !!!!). With annealing before every 3rd or 4th reload, brass lasts almost forever.

IMO, the exact length isn't as important as getting them all the same & then setting the die up for that minimum length. You can certainly get away with 0.010" shorter than max.

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NRA Cert. Inst. IDPA CSO

I've switched over to X-Dies in all calibers possible. Fredj338 is correct. It really doesn't matter how short you trim, but I've found that 0.010" below max sometimes allows the brass to grow too long. I tend to trim around 0.015" below max and have never experienced excessive growth.

Every reloading manual I have shows 1.75" as the trim length. I guess maybe I don't understand how the X-die works, but I thought the mandrel will be set at the brass length I settle on. If I then size a brass case, won't the top of the neck hit the mandrel and stop at that pre-set length?

If that is the case, then I don't understand how the brass would continue to grow unless there is some "spring-back" after sizing.

Mike

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NRA Certified Pistol Inst.

I follow the directions for my X-dies, 223 and 308, both are small base with no problems and good results.

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S&WHF 366

You need to reach some sort of equilibrium between brass growth and pressure of the neck against the mandrel. In my experience it take anywhere from one to four reloading cycles before that point is reached. I believe that's the reason that RCBS recommends shortening the case as much as they do.

I've used X-dies in .220 Swift and .30-06 for about ten years or so. They work very well. It's true the recommended trim length is quite short, but with all cases at a uniform length, all works out fine and you may never have to trim a case during its useful life span.

I just want to be sure before I dive into the huge pile of cases I have collected. I have found it is easy to take a little more off, but more difficult to put it back on

I have about 2,000 cases to process. I guess I will trim them all to 1.74". It sounds like that length is working for you guys.

The case edge still lands in the right place on cannelures at 1.74"?

Mike

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NRA Certified Pistol Inst.

They may or may not be in the right place with the trimmed brass. You'll just have to try it.

I don't use cannelured bullets or crimp .223s / 5.56s. With adequate neck tension, a crimp is not needed, though if done judiciously, a crimp probably does no harm.

Seating depth determines where the cannelure hits the case. I dont crimp 223, no real need, so seat to mag length less 0.020", works in all my aR. Trim 10 cases & get the sizing die dialed in before trimming 2000!?!

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NRA Cert. Inst. IDPA CSO

Messing around with my trimmer, I think I have decided on 1.742" nominal. My Redding 2400 trimmer does not trim every piece to exactly the same length and they can vary by as much as 0.0015". So at this setting they will be between 1.7405" and 1.7435". I had to go shorter than 1.75" because many pieces of the range pickup brass I am processing are already shorter than that, which means they were likely reloads.

I will let you know how they work out.

Mike

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NRA Certified Pistol Inst.

Ive found quite a bit of once fired brass to be shorter than 1.750". Look at 0.0015", its half a thickness of a sheet of paper, non issue. Its reloading, not micro surgery. Dont get too consumed by the measurements. After your first sizing in the X, they'll be fine.

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NRA Cert. Inst. IDPA CSO