New looking Die (to me at least)

Gary

SE Kansas
While browsing through a precision shooter/reloader website today I came across this thread about full length sizing and the pro's and con's of such maneuver. One fella has a die that ONLY sized the base of the brass and I got to thinking that it might be a good way to go if you use bump dies, ect. Anyhow, the die is a straight bore with a fine polish finish that is made to the specs of a single chamber, as I understand. Supposed to eliminate a sticky bolt after firing.

11914

As can be clearly seen in the photo only the base was touched. Follow that with a bump die and you should be golden. I would then use my Wilson Seating Die to finish the round.1575172023088.png
 

fiver

Well-Known Member
hmm.
put a 40* shoulder on the case and you could probably just neck size and not messs with the shoulder.
 

RBHarter

West Central AR
That would be roughly equal to having a small base Ackley die for a standard cartridge . Briefly I dabbled with minimal sizing for a hard to get Mag cartridge . As luck would have it I had a 458 WM die set that only sized about 1/4" above the belt and down to it . Short sizing was the answer there once fire formed to the barrel burner .

I have always , learn by example, been of the opinion that the more of the case left undisturbed and then consistently moved the more likely one is to have the same fit every time .

I have read of guys shooting a whole match with a single case and loading it for each shot at the bench and it marked for index , chamber , dies and press . All done in an effort to minimize shot to shot variations .

I would think that an AI die would do what you described as far as base and neck sizing with a shoulder bump .

The bench rest shooters are a whole new level of strange rituals in reloading . It's not uncommon for them to own a set of reamers that includes a roughing , chamber and die reamer with chamber and die laps made of hardened steel . They will often have or have access to tooling to correct ID run-out to 5-6 decimals vs production that's in spec at plus or minus .0005 for precision arms and sizing dies .
 

Brad

Benevolent Overlord and site owner
Staff member
Why laps of hardened steel? I thought softer lapped harder. Wouldn’t that also tend to cause the abrasive grit to embed in the softer barrel steel?
 

RBHarter

West Central AR
To eliminate wear for the final polish .
So much reading it may have been an example of one seeking an exact repeatable result when he cut 2" off the barrel with 827 shots fired ........... The eccentricities of the rail gun shooter seeking groups under .1 . The idea may have been to oil lap the last .0003 or some such . At the time it made sense .
 

RicinYakima

High Steppes of Eastern Washington
That is a new one to me also. Usually we used harden steel burnishers to do the surface finish on chambers. Never saw that it helped, but if it made the shooter more confident, well it worked.