Forming from 6.5G with Mighty Armory die

[StoneHendge]

Question for those of you who have made 6 ARC brass from 6.5 Grendel brass using a Mighty Armory die:

My early Hornady 6 ARC die would crush untrimmed 6.5G cases because the mouth of the brass would hit the top of the inside of the die. A few others also had the same problem, and trimming before sizing solves it.  I was just wondering if anyone who has formed ARC brass from Grendel using a Mighty Armory sizing die has run into this problem. I would prefer to trim after sizing. I will be using Starline brass FWIW.

[CZ527 Guy]

I have formed at least 200 6.5 Grendel to 6mm ARC, using the Mighty Armory die. I do not trim until after brass has been formed to 6mm ARC. I am using a light application of the home brew, lanolin spray lube. Great repeatable results with a buttery smooth stroke.

For what it is worth, I really like the Mighty armory full length die. Also really like the Whidden shoulder gauge linked below.

https://www.whiddengunworks.com/product/case-gauge-3/

[popgun]

I started converting before I got the Mighty Armory and just continued doing the same thing. I trim before sizing and within a couple of pieces I can get it so there's no need to trim a second time. Within a couple thou of 1.483". But if you can do it afterwards it would probably be better.

[markr6754]

I went straight from 6.5 Grendel to 6mm ARC using my Hornady sizing die. No issues whatsoever. There isn’t a top on the inside of a Hornady die, per se, it’s a hollow tube. I’m wondering if you were hitting the decapping rod.

You already have a better sizing die in the Mighty Armory, but should someone else make the same attempt with a Hornady die…size first with the decapping rod/expander ball out of the die. Then trim to length, then run it through with the expanse ball in place.

Another recommendation is to anneal the Grendel brass prior to re-forming to 6mm ARC.

[CZ527 Guy]

I am not sure I would agree, regarding annealing prior to re-forming, on the other hand there may be merit to annealing prior to fire forming.

Thinking you may be on to something regarding the decapping rod collet, providing the interference that would give a situation that may be where crushing cases may become problems.

[Old Bob]

If you resize the Grendel brass in a Hornady 6 ARC die without the de-capping rod/neck expander installed, the case necks will be undersized for the trimmer pilots used in piloted case trimmers like RCBS or Lyman. Little Crow or L.E. Wilson trimmers are what you'd need for trimming. Or, you could reinstall the de-capping rod/expander & run your brass over it to expand the case necks while being careful not to crush the shoulders. Just don't run the cases back up into the neck area of the die. Another way would be to use a neck expander die with a .241" mandrel. That's what I'm doing now. You can get mandrels in other diameters. It depends on how much case-neck/bullet tension you desire.

[StoneHendge]

I've got 200 pieces of Starline formed thus far and using this die is like sizing butter. Far easier than the many pieces of 6.5G Hornady brass that I formed into 243 LBC using a Redding 6.5g bushing die (which didn't involve a 0.03" shoulder bump) and also the 400 of Nickel plated Starline that I formed into 6 arc using a Hornady 6 arc die. In both those cases, I used the RCBS lube you use on a pad and used a cotton swab to apply it to the brass shoulder and the inside of the neck

I've been almost exclusively using a mix of standard 100% lanolin and 99% isopropyl as a lube since the scamdemic started. I think its a 10/90 mix - I honestly forget and go by the markings I have on my spray bottle when I fill it. I gave that a try before changing to what Mighty Armory recommends (including the pricier PEG 75 lanolin) and it works just fine (as well as costing less than 20% of the Hornady spray lube!). I also didn't bother to let it dry for 30 minutes like Mighty Armory suggests - I just sized like I always do by wiping the shoulder and neck with a rag wrapped around my hand prior to putting the brass into the press to prevent hydraulic sizing. Results were perfect and I didn't crush a single piece of brass nor did I get any dimpling on the shoulder. I'll note that after sizing, I do run it in a tumbler with corn cob media (or a mix of corn cob and rice) to remove excess lube. That also leaves primer pockets clean with fired brass, although some do need to get quickly run through a decapping die to remove media that may get stuck.