Using an RCBS 7.62x54r neck sizing die on a 7.7 Arisaka

[BJung]

I jumped the gun and purchased an RCBS 7.62x54r neck sizing die for my fireformed 7.7 Arisaka. A FL RCBS Arisaka die turned back will still swage the fireformed shoulder. Has anyone tried using this neck sizing die and did you experience excessive run-out. Lee is not making collet neck sizing dies at this time.

 

[Mark_Mark]

I jumped the gun and purchased an RCBS 7.62x54r neck sizing die for my fireformed 7.7 Arisaka. A FL RCBS Arisaka die turned back will still swage the fireformed shoulder. Has anyone tried using this neck sizing die and did you experience excessive run-out. Lee is not making collet neck sizing dies at this time.

I bought Norma 7.7 brass from members here for a average of $.65. 1/2 new and once fired.

 

[AJC1]

The die must be shorter than your chamber. You can back it out more and see if that helps. I have not compared case specs to see if this is a workable plan but I'll assume you have????

 

[BJung]

Yes, the 7.62x54r case is shorter than the 7.7 Arisaka. The case width across the shoulder is .457" for the 7.62x54r case vs .435" for the 7.7 Arisaka. Does anyone know of a machinist that can ream my 7.7 sizing die to my chamber?

 

[AJC1]

Yes, the 7.62x54r case is shorter than the 7.7 Arisaka. The case width across the shoulder is .457" for the 7.62x54r case vs .435" for the 7.7 Arisaka. Does anyone know of a machinist that can ream my 7.7 sizing die to my chamber?

For the money it most likely will be cheaper to get the 7.7 die set. If that's your desire I can help you hunt.

 

[BJung]

Thanks but.. I have an RCBS die set that sizes the case with a sharp shoulder. My fireformed cases are wider and the shoulder and the shoulder is round like a photos I see of a Weatherby case. Trying to neck size with the FL Die still swages the shoulder. Ideally, I'd settle on someone to ream out my FL dies to match my chamber but I don't know if this can be done.

 

[AJC1]

Thanks but.. I have an RCBS die set that sizes the case with a sharp shoulder. My fireformed cases are wider and the shoulder and the shoulder is round like a photos I see of a Weatherby case. Trying to neck size with the FL Die still swages the shoulder. Ideally, I'd settle on someone to ream out my FL dies to match my chamber but I don't know if this can be done.

The path normally in this case is to send in 3 cases to have a custom sizer made. The alternative would be to find a neck sizing die with enough clearance. A completed die is heat treated and hard as hell. I dont know any die makers on this board or any for hire machineests. Carlsbad on accurate shooter may take the job. He does a pile of quality bolt work and is very experienced.

 

[BJung]

Thanks for the contact. I just reviewed the Lee website and a 7.62x54r collet die is made. This might just work instead if the RCBS neck sizing die doesn't work.

 

[Bcwitt]

You said fire formed. I hope you aren't making those from 3006 or similar? I have personally ruptured a case exactly that way.

 

[BJung]

Yes. I have fireformed cases from military 30-06 brass and Norma 7.7 Arisaka brass. My accuracy loads are not near the maximum.

 

[LoonWulf]

Can we see a picture of your cases, thats dosent sound like a normal 7.7 chamber?

 

[BJung]

Here is a photo of a swaged 30-06 through my 7.7 Arisaka die and another case that was trimmed.

 

[BJung]

This is the only photo of a have with a fire formed case loaded with a Hornady 174g HPBT

 

[AJC1]

So if I'm following, and maybe I'm not, you want to use fire formed brass in your 7.7 and you want to neck size. Your forming brass with an rcbs fl sizing die. You want to neck size because your FL die is oversizing your brass. Maybe this is what you want

 

[BJung]

My FL die swages the shoulder so I'm resorting to a 7.62x54r neck sizing die. I plan to purchase a Lee 7.62x54r collet die next. Lee is not making custom 7.7 Arisaka collet dies at this time. I'm asking how other 7.7 Arisaka reloaders have resized their cases using this method and how was their accuracy.