The Last 5.7mm Johnson Post (maybe)

[hdwhit]

I am still working on reloading for a 5.7mm Johnson carbine. This is a 30 Carbine case necked down to 22. I bought the dies to form the cases from RCBS. The die set contains a 1) Forming die, 2) Trim Die, and 3) Full-length Sizer. Each of the three dies forms a part of the case shoulder and neck. I set up the dies according to the instructions I got from RCBS, but the resulting cases evidence head separation on first firing.

I know this means I am setting the shoulder too far back. What I need some guidance on is which die should I adjust first and how should I adjust the subsequent dies to get the shoulder dimension correct.

Thank you, in advance, for your constructive posts.

 

[LoonWulf]

Could we get some pictures of your cases at each step?

If the trim die finishes the shoulder I'd be inclined to adjust it out untill a case won't chamber, then back in till it just chambers without resistance. Do a few and see if they also chamber without resistance.

 

[JT-AR-MG42]

I'll second LoonWulfs suggestion.
Or you could also try a few without using the trim die at all ( use a hand trimmer such as a Wilson instead), and let the sizing die
set the shoulder back for chambering.

JT

 

[FROGO207]

My first step would be a chamber cast with Cerrosafe making sure the entire chamber was done then take the calipers and measure length. Next measure the length and set dies to only size that far (or a smidge longer) before trimming anything. If you get it too long it can be bumped back a bit at a time until it fits. Do this last bit with the expander ball/decapper removed when sizing with standard sizing die until you find the correct length. Note your case necks might be too tight and will require turning to work with a standard 5.7MM bullet. This outer neck dimension will be shown when you chamber cast if you go past the neck into the leade area of the barrel a small bit. This will be needed if the bullet expands the neck past the chamber cast diameter. This may play a part in the case head separations if the bullet is getting pinched in the neck area when fired as it starts to move and the brass move backwards.

 

[hdwhit]

Loon Wolf asked:
Could we get some pictures of your cases at each step?

At this point, no.

The dies, the press - in fact all of my reloading equipment - has been packed for relocation to my new home.

The process is Forming Die, Trim Die and then Sizing Die.

Each die plays a role in forming and setting the shoulder of the case.

The "initial set" is performed by the Forming Die.

 

[hdwhit]

Sorry everyone.

I didn't mean for this to be a "drive-by" posting, but between the time I made the original post and today, my father-in-law had a stroke and a short time in hospice before passing away. He was 91. He's the one who - on the shotgun forums you can read about giving me his Browning Auto-5 as collateral for a "loan" I assumed would never be repaid. I had already gotten his oldest daughter as my wife and as far as I'm concerned she was more than worth any shotgun on earth.

 

[Walkalong]

Without seeing the results of each die, my first thought it you are ok on the forming and trim die, but need to adjust the final sizing die. Adjust it up and try a case in the gun, if it chambers measure where the shoulder is, then load and fire it, then measure the shoulder position on it vs where it started after coming out of the sizer. That will show you where you are. If it doesn't chamber, keep adjusting the sizer down an 1/8 turn at a time until it does, then fire a round to get a case formed close to the chamber.

 

[hdwhit]

The 5.7mm Johnson, supposedly, used 0.224 bullets. Some of the barrels used on rifles assembled by Iver Johnson were, when cast, determined to be "somewhere between" 0.224 and 0.223; call them 0.2335.

I have already dealt with the 0.224/0.223 problem with the cartridge.

What I am asking about has to do with reloading the cartridge. The RCBS Form die, RCBS Trim die and RCBS Full-length seater die each perform part of the work of creating and then setting the neck on the cartridge. As presently, adjusted, the three dies together form a neck that is several thousandths of an inch too short.

What I need to know is the order in which to adjust the three dies so as to get to a length that is appropriate for the chamber.

Thanks.

 

[hdwhit]

walkalong wrote:
"...measure where the shoulder is..."

To my knowledge, nobody makes a case gauge for the 5.7mm Johnson. In the absence of a gauge, any determination of where the shoulder "is" or "begins" must be made by visual comparison with respect to chamber castings and that is - at best - a subjective measurement.

 

[Walkalong]

What I need to know is the order in which to adjust the three dies so as to get to a length that is appropriate for the chamber.

That is what I thought I addressed. I guess I didn't do a good job. Sorry.

To my knowledge, nobody makes a case gauge for the 5.7mm Johnson.

You don't need a case gauge. Be creative. 243winxb posted a pic here once where he used a .223 case with the neck cut off to measure .223 brass shoulder position. Slide the neckless case over the neck of the sized brass and up to the shoulder.

Imagine a neckless case in place of my home made gauge. Measure the same way.

 

[Walkalong]

Tell me the angle of the shoulder on the 5.7MM Johnson and I will make you a gauge like pictured.

It doesn't have to be fancy to measure shoulder position.

https://www.ctstrimmer.com/case-gauges/21-case-gauge.html
.

 

[hdwhit]

walkalong wrote: "Tell me the angle of the shoulder on the 5.7MM Johnson and I will make you a gauge like pictured."

Thank you.

All of my dies, cartridges and castings are packed for relocation, but I will post then as soon as I am un-packed - proabably in February/March 2019.