Forster seating dies

From Google:
The Forster .303 British seating die may not be directly compatible with the 7.7mm Arisaka. While both cartridges share similarities, including the .311-.312 bullet diameter, there are important differences. Here’s what you need to consider:

Case Length and Shoulder Angle:
The 7.7mm Arisaka has a longer case length and a different shoulder angle compared to the .303 British.
Attempting to use a .303 seating die on the 7.7mm Arisaka could lead to improper seating depth due to the different case dimensions.
Neck Sizing Die:
Some reloaders recommend using a .303 neck sizing die for the 7.7mm Arisaka because of their similarities.
However, it’s essential to verify that the neck sizing die aligns properly with the Arisaka case neck.
Load Data:
Be cautious when using old load data, especially from sources that don’t provide pressure figures.
The 7.7x58mm Arisaka is stronger than the .303 British, so load data should be specific to the Arisaka cartridge1.
Invest in current reloading manuals or consult reliable online sources for up-to-date information
 
Made my own tool

Thanks for your information. I went to the hardware store with the intent of making my own tool to line up my .312 bullet onto an Arisaka case mouth. I find two. The first is aluminum cable clamp. I only have to drill holes on each end. One end to line up the case and the other side large enough for the bullet to slide through. Then I found nylon space for 57 cents. The bullet fits through it perfectly. I plan to drill a larger hold into one end so the spacer slides over the case so the smaller holes runs in line with it. I expect the seating stem to at least start the seating process.
 
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