Good-Day To All:

The other day I was re-sizing some 9.3 brass. I had ordered from the Lee custom shop, the case trim-to-length guage in 9.3x74R.

After rezising the brass, I tried to trim the cases to length however, the guage would not fit into the case mouth.

I measured the guage and it is .364" diameter. Then I measured the inside case neck of the cartridges and they are .361-.362" diameter.

I measure the expander ball on my RCBS die and it is .3645" diameter.

Figuring my expander ball was the wrong size, I phone RCBS and explain the situation. They tell me they will put a new expander ball in the mail, free of charge.

I contact a buddy of mine who also reloads for 9.3x74R and borrow his RCBS sizing die. I measure the expander ball and it comes out .3645" diameter.

I am still waiting for the new expander ball from RCBS. It's been two weeks and will probably be another two weeks before it gets here. Anything coming from the USA to Canada usually takes a while.

Would those of you who reload for 9.3x74R measure your expander balls and and let me know here, who makes the die and what diameter the expander ball is.

I have been reloading for decades and have never encountered a situation like this with all the other calibres I reload for.

Comments, questions and concerns always welcome.

Kindest regards,

Carpediem

Mine are RCBS and the expander measures .3635.
These dies are about 12-15 yrs old and have loaded lots of ammo. For Chapuis,Valmet and Ruger. Have had absolutely no problems with them.

I had the same problem years ago. I put my trimmer pilot in an electric drill and just polished it down a little bit, using sand paper backed up by a file.
My "custom" trimmer pilot hasn't given me any trouble since...

I would be very careful not to over-expand case necks. Your measurements look normal IMO and could possibly need to be reduced slightly. As a general rule I tend to reduce the expander .002 under bullet size. Proper neck tension is critical to prevent the bullet from coming out of the case in recoil. This is much more critical in a double rifle than any other type of firearm since there is no magazine to prevent the bullet from sliding out of the case on the second round. Proper neck tension and a light crimp is the method I prefer. Lack of neck tension requires a heavy crimp, which leads to a whole different list of issues. I would focus on the trim gauge and not the expander die.

Good luck

I have a Hornady trimmer and use a Hornady pilot. No trouble so far.

Further investigation showed the neck tension on the 9.3 brass, after sizing, to be .oo4". I checked other calibres and the average was .004". This average tension was produced by several different die manufactures: Lee, RCBS, C&H, Hornady.

Everything I have ever read, indicated .002" neck tension was what you wanted, so as to exert proper pressure and not distort the bullet. Especially if you are using cast bullets.

While measuring neck tension, I am also measuring other Lee trim-to-length guages. On average, the guage was.005" smaller than the calibre. I measure and try my 9.3 guage again and try fitting it into the case; this time backwards. Well, the damn thing fits perfectly. BUT, it will only slide into the case approximately one third of the way. Obviously, the nimrod at Lee making this thing DID NOT try the guage before shipping and he/she tapered the guage .

So, the next question is how much neck tension is enough and should the mouth of the case be slightly flared to accept the bullet prior to seating in place? Much like what the Lyman M die will accomplish.

KIndest regards,

Carpediem

I just checked a new set of RCBS dies I got last week .3645. But who know's how long they were on the shelf before I got them. Craig

coyote wacker:

That is what mine measured.

Now, I took this thing one step further. Today, I removed the primer decapping rod from the sizer die and resized the cases. I used a fired case with a neck diameter of .368"

Since there is no sizer ball, I am getting the amount of swaging the neck is getting before it gets resized by the expander ball.

My case necks were compressed to .353" diameter .

I then screwed the deprimer rod and expander ball back into the die and expanded the neck.

The case neck was expanded to .362" diameter.

I am thinking that .009" resizing of the neck everytime I resize my case is excessive. Would the other 9.3 reloaders try this little test and let me now what you get.

Kind regards,

Carpediem

I think many dies made oversize the case neck. My current 308 RCBS dies, size the neck down about .012" on my R-P brass and I have other dies that do just about as much. Way too much sizing, I think, on the necks

RCBS dies. Expander ball .3643" Sized case neck .3782" dia. With exp. ball in place .3838"

Older Lyman dies. Expander ball .3636". Sized case .3748" dia. and with exp. ball .3832"

Sized down about .005" more than they need to be.

quote:

Originally posted by carpediem4570:
coyote wacker:

That is what mine measured.

Now, I took this thing one step further. Today, I removed the primer decapping rod from the sizer die and resized the cases. I used a fired case with a neck diameter of .368"

Since there is no sizer ball, I am getting the amount of swaging the neck is getting before it gets resized by the expander ball.

My case necks were compressed to .353" diameter .

I then screwed the deprimer rod and expander ball back into the die and expanded the neck.

The case neck was expanded to .362" diameter.

I am thinking that .009" resizing of the neck everytime I resize my case is excessive. Would the other 9.3 reloaders try this little test and let me now what you get.

Kind regards,

Carpediem

I checked my RCBS dies and came up with the same numbers. What I think I'am going to do is make chamber casts of my DR. And work backwards from there. If I need to I will send the dies and fired cases to RCBS to correct the problem.
Craig