Neck Reaming - 7.62X25


April 21, 2014, 05:53 PM
I've been reforming .556 down to 7.62X25. In an earlier thread I recounted problems with neck thickness. I've found with reaming with a .3125 reamer leaves me with a neck thickness of about .013. I seated a couple .308 jacketed bullets and they chambered.

Does that thickness sound adequate?

In the archives, I also learned that some were using .223 brass and didn't have thickness problems. Can anyone verify that?

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April 21, 2014, 06:49 PM
Sounds good. A bit thicker than some necks. A chamber cast would tell you for sure what you need. Measure the neck of a loaded round. What is the SAMMI spec for a 7.62X25 chamber?

Since it chambers, fire one. Check to see how easily a new bullet will slide into the fired neck. If you have plenty of slop, your golden.

April 21, 2014, 09:06 PM
Thanks, I'll give it a try.

Can anyone comment on the use of the .223s instead of the .556?

April 21, 2014, 09:24 PM
Check to see how easily a new bullet will slide into the fired neck. If you have plenty of slop, your golden.Yes, do that!

If a new bullet will fall in a fired case, you are fine!

If the necks are still too thick, a new bullet would be a tight fit in a fired case.

And you sure don't want that!!


May 3, 2014, 11:40 PM

Following some of the info in the archives, I bought a Forster trimmer and their neck reamer for .308 bullets. It works fairly well and leaves the neck inside nice and smooth.

The problem now is the reamer, per Forster, is .002"-.003" larger than the bullet and the bullet falls into the case even after a run through the sizing die. The rim thickness is about .009". I found I can overcome this by very, very slightly "crimping" a small edge of the neck to hold the bullet in place for the seating process. The necks are smooth when seated.

Anyone see a problem here?

May 4, 2014, 09:23 AM
They make different size reamers. Get the right one. You really do want good neck tension.

May 4, 2014, 08:13 PM
I bought the one Forster offered for the .308. I can crimp the bullet tightly.

May 4, 2014, 08:45 PM
"neck reaming should be done after the case has been fired with a full load
and before the neck or full length sizing operation. " Neck diameter
8.48 mm (0.334 in You should ask Forster how that works when forming brass from 223??

May 4, 2014, 09:30 PM
It's sort of hard to fire a case when you are reforming.

There are several threads in archives regarding this reforming. At least one, maybe two, reference using the Forster reamer.

May 4, 2014, 09:54 PM
Outside neck turning may work better , but it depends on how much needs to be removed? ? The neck reaming i did held the case in a die while reaming. This gives a more exact wall thickness then using a fired case. Use a reamer thats smaller than needed. This leaves a little extra wall thickness. So after reaming, its best to make a final cut by outside neck turning.

May 4, 2014, 10:09 PM
Your on the right track. 223 definitely needs to be reamed. I have both the .309 and .311 reamers and use have settled on the .311 , because I wanted a little bit thinner neck.

I only shoot cast bullets, so it allows me to use a larger reamer because of going a tad over the slugged barrel diameter. I have a number of CZ52s and TOKs and a .308 reamer would be too small for all of mine, as with a larger diameter bullet, the neck would still be too thick to chamber good.

If you're using the LEE die set, you can usually get a good enough crimp on the bullet with the factory crimp die for that first firing. After that, you might be OK.

Another thing you can try is to run it back through the sizing die after reaming. sometimes I have seen where some brass may actually open back up in the neck in this process due to the brass being thicker there when you size it after trimming, and because brass is usually harder in the main body of the brass where you are getting the new neck from. The thinned brass sometimes will size down just a bit.

I have found the Forester trimmer is the ticket for me. I made a small device that I use to measure and mark the brass for cutting, then I use a small tube cutter and a Lee Zip Trim with a 3 jaw chuck to cut it with a small tube cutter and also use steel wool to polish it while in the zip trim. Then I size it and then into the Forster for trimming and reaming all in one shot. Then back into the zip trim for a quick champfering with a small Lee champfer / de-burring tool, and walla, a nice piece of brass in less than a minute.

You're definitely on the right track. Just keep messing with it until you get the end result you need. Keep us posted if you will. I've never used .556 brass. Is there much of a difference? If I get some, your info might help save some messing around if there is a bit of a difference.

May 4, 2014, 10:26 PM Huntington wants $234.98 for case forming dies. :eek:

May 4, 2014, 10:34 PM
I wish they had a picture of that high priced gadget. Surely it can't be as simple as a sizing die! Wowsa!

You can really crank them out pretty quick with what I said above, but a drill and three jaw chuck would also work.

Didn't RCBS market something similar? I thought they did a few years back, but I can't say I ever saw one of those puppies either.

May 4, 2014, 10:48 PM
RCBS & Huntington are right next door to each other. I forget the connection, but Huntington is RCBS for the most part. Googled it - RCBS, Inc. was founded by Fred Huntington in 1943 in Oroville, California

May 5, 2014, 12:59 AM
I've tried sizing after the reaming, but there's no apparent change because the metal I've removed was on the inside. I found that just a very slight "crimp" (maybe 1/16") to a small portion of the neck edge holds the bullet sufficiently for the seating/crimp. The loaded rounds fit the chamber nicely.

I think I'll fire some of the loaded cartridges and see what comes out the other side.

PS: I've done both 5.56 and .223 and there doesn't seem to be any difference.

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