FL Die Adjustment for a 7.7 Arisaka fireformed case

[BJung]

How do you set your resizing die for your fireformed cases?

I am reloading for a 7.7 Arisaka and the case shoulder is round than with a sharp angle. My FL resizing die will swage the shoulder to be sharp and the diameter of the case narrower. Do you neck size or do you adjust the die down to where it bumps the should back slightly?

Information

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[Bruce McAskill]

As your brass is fited to the chamber more or less you only have to neck size the case.

[BJung]

In the past, it was believed that neck sizing is adequate. I use to use a custom Lee Collet Neck sizing die until I broke it. And so, I have an RCBS neck sizing die for my 7.7 Arisaka now. With three rounds left with cases necks sized with the Lee die, I can compare runout with loads having cases neck sized.

There are many online claims that FL sizing is more accurate that neck sizing. I'm thinking that the case is not run all the way into the die but just enough to bump the shoulder back 0.001". But, this isn't the case with the fireformed case to the chamber to the RCBS sizing die. It could pretty much deform the shape of the fire formed shoulder that's round.

I want to shoot 300 and more with my Arisaka and need the most accurate load. The sights don't help.

[CINDERS]

You'll find after a while just neck sizing the case after many repeated firings will become hard to chamber, if your just neck sizing from possibly a couple of things if you do not neck right to the end of the neck.
You can get a doughnut effect as the brass flows this part of the neck will not fit into the chamber neck.
The other is the brass grows moving the shoulder forward causing hard chambering, I use a body die on my 6.5/284 to adjust the shoulder so the bolt has a certain feel on closing like camming the round into the chamber shoulder ever so slightly but that's an F open 1/3 - 1/2 MOA rifle.

I used to neck my 303's then say after 4 or 5 reloads I'd FLS them but really gave that away and went with doing it every time as then I do not have to worry about mixed brass having 4 shooters, I do however check length and TTL if required I also anneal them every firing.
Plenty of info on the net with reloading but as always work up slowly I'd suggest doing a ladder test find a powder/projie combo that works and stick with that you can then play around with that load to wring even more accuracy out of it but again only change one thing at a time.
Trust me I have done allot of loadings finding what worked in all my 303's and for me now its AR2209 and 174Gn SMK's I have some new Taipan 174Gn FBHP's .312's to try out, I used them years ago when Malcolm Bone was making them and they were absolute lasers as far as accuracy went with the 303's just cleaned up and these look like the goods.

[Bruce_in_Oz]

Mass-produced rifles firing even more mass-produced ammo?

NO consideration given to reloading. The ONLY objective was to ensure the rounds chambered and went "bang", whilst sending a bullet down-range.

I somehow doubt that Japanese troopies were scrabbling around, recovering their brass so they could reload it after the day's "activities"

You just have to live with the "generous" chambers if you insist on firing these historical pieces. These are NOT "bench-rest" rifles..

I would pretty much guarantee that if you have an early 99 and a late (but not "last-ditch" 99), there will be chamber variations.

[tiriaq]

After being fireformed, the headspace relationship is correct for that case/chamber combination. If resizing pushes the shoulder back more than a very few thousandths, you will be creating an excess headspace situation. The neck needs to be sized to securely hold the bullet. The shoulder and body only enough to insure easy chambering. Adjust your FL die accordingly.
Excess headspace can result in case separations. If you are forming your cases from a parent case that is slightly smaller in diameter than 7.7 factory, you don't want separations.

[rugersworld]

Basically how it is done...
raise the ram on your press all the way.
screw in the die so that there is about a dime's worth of space between the ram and the die bottom. tighten the lock ring.
if you are also depriming, make sure the pin protrudes enough to knock out the primer.
lube your case neck in and out.
Run case into sizing die then look at the neck to see how much lube has been wiped off. you should see a lube line.
check case for length and trim if needed.
good luck have fun.

adjust the die up or down as necessary for the amount of neck you want sized.

[BJung]

Yes, that's how I have necks sized. But how to you FL size? I suppose you turn the die in so the shoulder is bumped. I never thought I was having problems necks sizing my case necks with a FL die the way you said. But now, there are those that claim FL sizing is the best. If Lee could make a custom FL die, I would buy one of these or maybe even another Collet neck sizing die but their custom shop is closed because of the pandemic.

[BJung]

Attachment 121611

I found a youtube video comparing necks sizing to the Lee Collet neck sizing die and neck sizing vs. FL sizing. For the rifle I have, I've concluded the difference, if any is very minor. Here is an image of my attempt to neck size using an RCBS 7.62x54r neck size only die and an RCBS 7.7 Arisaka die partially screwed down to neck size only. Case on the far left is the fireformed case. It appears that the partially screwed in FL die can neck size my fire formed case without bumping the shoulder back while the 7.62x54r neck sizing case swaged the shoulder down by the time I neck sized the 7.7 case. I thought that the width of the 7.62x54r case was wide enough to clear the 7.7 Arisaka case shoulder. Apparently not.