Educate me on bushing dies

[clrems77]

Looking for new dies for a 6.5CM rifle being built. Ive been using a Forster F/L die set with micrometer for my .308 with great success. I now see that Redding and Forster both have dies with neck bushings for adjusting neck tension. Please excuse the dumb question, but do you not get consistent neck tension with the normal expander ball in a F/L die or is the bushing set used just so you can customize the tension to your preference? Is this something worth purchasing?

This will be for a Remington bolt action 6.5CM used for weekend fun. Bartlein match 26" barrel without break, handloaded Hornady A-max bullets (To start with) in Hornady match brass with what ever decent powder I can find.

Thanks in advance!

 

[mdmp5]

Bushing dies allow you to size your neck down to a desired diameter for a neck tension of your choice. A standard die undersizes the neck, and the final diameter is dependent on the caliber of the expander ball. This is a poor method of sizing, because with some thinner types of brass, the ball will rip the mouth open too much and there will not be enough neck tension to hold the bullet. It also induces runout.

 

[witchhunter]

Expander balls are the devils work! Bushing dies are oh so smooth. Bushings are also easier on the brass. I have made some very accurate ammo with standard RCBS dies before I discovered the bushing dies by Redding though.

 

[buffybuster]

Standard non-bushing sizer dies tend to reduce to the minimum dimension, so they will work with everything....... But that leads to excessive neck tension, which can lead to erratic bullet release, etc. IMO that's not a huge deal, unless you're chasing every tenth, and continue to use a standard die for many of my rifles.

A bushing die allows the use to set the amount of neck resize by the use of different size bushings. By neck turning and/or using a specific lot/brand of brass you can more closely control how much you resize the neck. This can also be done by honing a standard sizing die (Forster provides this service for a very modest fee). Those using bushing is more convenient because bushing can be changed out easily. The thought behind this is controlling the amount of neck resizing will control the amount of neck tension. You will often hear people say "I'm running 0.001" or 0.002" of neck tension." which is suppose to be quantified statement.

In reality it is not quantified. Neck tension is more complex than merely setting the amount of neck resizing. How clean or smooth the neck is can have a dramatic impact on neck tension. New brass or brass cleaned in the wet process with SST pins can experience neck weld. Using bushing dies requires some understanding of tolerances and keeping things consistent. It does work the brass less, possibly increasing caselife.

The counterpoint, of mindlessly pulling an expander ball through the neck is not the best thing either. The expander ball can be polished or a custom diameter ground.