Please help me understand bushing die set up

[MJY65]

I'm getting ready to start loading for my TRG22 and want to set it up right. I've loaded plenty of ammo over the years, but this is my first time with a bushing die. I purchased brand new Lapua brass and an RCBS bushing die. I made up a sample cartridge with my chosen bullet, 175 SMK, and got the correct diameter bushings per RCBS instructions. I removed the expander ball and replaced it with the undersized decapping pin holder supplied with the dies.

I now have two questions:

First, at the risk of sounding stupid, I'm guessing the set up with the undersized pin holder can only be used once the brass has actually been fired in my rifle since there is no expander ball to round out the case mouths. Is that correct?

Second, How much of the neck do you leave unsized, or put another way, how far down the neck do you set the bushing?

Thanks for your help.

Mike

 

[waste_knot]

If it's a FL die you set the shoulder length dimension a couple of thou less than headspace. If it's a neck sizer set the die down to the shell holder. The intent is to size the entire neck.

 

[MJY65]

In the instructions it talks about setting up a "double diameter" on the neck so that the portion near the shoulder is not getting resized and will add support in the chamber. I guess I don't understand the purpose of the floating bushing if the whole neck is getting resized.

 

[JB02]

Some shooters like to experiment with how far down the neck they want to increase the neck tension. Some only go between 1/2-3/4 down the neck. Redding even sells dies with a micrometer adjustment for this feature.

I don't bother messing with this. I have uniform neck tension all the way down to the shoulder.

I removed the expander ball in my neck die because the bushing sets the neck tension. If part of your case mouth is bent inwards, you might need to put it back it to get uniform inner diameter concentricity.

Since I use a decapping die, I removed the decapping pin on my Redding die; however I just received a Redding Full length sizer with an S type bushing. This die will allow me to bump back the shoulder, punch out the spent primer, and size the neck with desired neck tension all in one stroke.

 

[waste_knot]

In the instructions it talks about setting up a "double diameter" on the neck so that the portion near the shoulder is not getting resized and will add support in the chamber. I guess I don't understand the purpose of the floating bushing if the whole neck is getting resized.

Quote from RCBS instructions:
"The amount of the case neck that is resized is adjustable by adjusting the Neck Bushing retainer upwards. This allows the Neck Bushing to move upwards before neck resizing begins. A full turn is approximately .0712", this creates a double diameter neck with the base of the case neck further helping to center the cartridge in the chamber of the firearm."

Double dia. means the bottom section of the neck is not sized down from the last firing so that section fits the chamber exactly and acts as a centering guide. The top portion of the neck is only sized down to grip the bullet. If you have a large neck diameter in the chamber (as in factory) this double dia. may help increase accuracy. The neck dia in one of my match chambers produces 0.338 brass and the thicker wall brass will actually grip bullets after it is fired.

 

[ChrisGarrett]

Quote from RCBS instructions:
"The amount of the case neck that is resized is adjustable by adjusting the Neck Bushing retainer upwards. This allows the Neck Bushing to move upwards before neck resizing begins. A full turn is approximately .0712", this creates a double diameter neck with the base of the case neck further helping to center the cartridge in the chamber of the firearm."

Double dia. means the bottom section of the neck is not sized down from the last firing so that section fits the chamber exactly and acts as a centering guide. The top portion of the neck is only sized down to grip the bullet. If you have a large neck diameter in the chamber (as in factory) this double dia. may help increase accuracy. The neck dia in one of my match chambers produces 0.338 brass and the thicker wall brass will actually grip bullets after it is fired.

I started playing with neck sizing depth with my 338LM loads in the beginning. Going halfway, then two thirds. I would get the false shoulder and all that, but ended up stopping the practice. Case necks looked stupid and personally, the carts will be self centered by the case body as well, not just by that double step in the neck region.

With my Redding bushing neck/FL sizing dies, I go down as far as I can, while still retaining some 'free float' for the bushing itself.

If I want to have less tension on the bullet, which is one of the reasons for partial neck sizing, I'll just pick a bigger bushing, as I generally keep more than one size per cartridge.

Chris