Die Shims

[Lesloan]

Sinclair sells die shim sets in varying thicknesses. What are they for, and how are they used? I'm guessing they are intended to prevent pushing the case shoulder back when FL resizing for a specific rifle where FL resizing is necessary; for example, an AR-15 or other semi-auto. Am I correct?

 

[fdshuster]

I use them for loading for multiple chambers, same cartridge. Example: 6BR, have 5 chamberings, 2 with identical headspace lengths,(cut with my reamer), 2 others same headspace cut with another one of my reamers, and the fifth cut with my gunsmiths reamer. So, three different headspace lengths to deal with.

Without the shims I would have to constantly change the adjustment(s) on my Redding FL neck bushing die, by re-adjusting the die lock ring, a pain in the a**.

I have the die adjusted for the shortest headspace length, 1.152", and add the appropriate shim for the 1.155" and 1.159" lengths.

Would also work fine for the AR-15 example you used. The sizer die could be adjusted for tighter headspace on a bolt-action 223, and add a .002" or .003" for sizing cases for an AR-15. I've done that also.

 

[bigedp51]

I use Skip's shims on my beer keg tap to prevent excess headspace. :

The shims help when reloading my glass,.......below the worst type of excess headspace imaginable.

NOTICE: No beer was harmed or injured during the filming of this posting. ;D

 

[Lesloan]

I use them for loading for multiple chambers, same cartridge. Example: 6BR, have 5 chamberings, 2 with identical headspace lengths,(cut with my reamer), 2 others same headspace cut with another one of my reamers, and the fifth cut with my gunsmiths reamer. So, three different headspace lengths to deal with.

Without the shims I would have to constantly change the adjustment(s) on my Redding FL neck bushing die, by re-adjusting the die lock ring, a pain in the a**.

I have the die adjusted for the shortest headspace length, 1.152", and add the appropriate shim for the 1.155" and 1.159" lengths.

Would also work fine for the AR-15 example you used. The sizer die could be adjusted for tighter headspace on a bolt-action 223, and add a .002" or .003" for sizing cases for an AR-15. I've done that also.

The only rifle cartridge I currently reload is .223 Rem. I have 2 of these, a Savage Mod. 12 VLP single shot and a just-purchased AR-15. For the Savage, I neck size (using a Lee Collet neck sizing die) till cases start getting hard to chamber, then FL resize (Hornady dies.) For the AR, I know I'll have to FL resize all the time. I bought a set of the shims, planning to use them with the FL resizing die by stacking all the shims between the press & die, sizing, then looking at how far down the case neck the sizing actually occurred. Then removing the shims one at a time till the sizing is just off the case shoulder. I can do this, I think, for each rifle then record the shims to be used when reloading for each.

What do you think? Is this feasible? I've never loaded for semi-autos before, and have only done neck sizing and FL resizing as needed for bolt actions and, years ago, lever actions. I'd like to keep case forming to the minimum necessary & thought this might be a way to do it.

 

[Lesloan]

I use Skip's shims on my beer keg tap to prevent excess headspace. :

Now that's what I call thinking out of the box!

 

[bigedp51]

Lesloan

Don't guess, get a Hornady cartridge headspace gauge and shim your dies accordingly. Remember you can push the case shoulder forward with too many shims and over resize with to few shims. You will need to experiment till you find the sweet spot.

Above I use a GO gauge as a "zero" reference point when using the Hornady case gauge and setting up the dies.

Full length resizing
Bolt action rifles should have the shoulder pushed back .001 to .002
Semi rifles should have the shoulder pushed back .002 to .005

 

[Lesloan]

I'm confused. Seems to me that too few shims would result in the shoulder being pushed back too far, not forward. The only way I can think of for moving the shoulder forward is to fire the round. Can you clarify? Thanks.

BTW--I've never used a headspace guage in anything but a Browning .50 cal. M2 machine gun, aka "Ma Deuce" and this was just "go" and "no go." I'm pretty sure this is not what you're talking about. : I assume the Hornady unit comes with instructions?

 

[jo191145]

10.5 0n the excess head Ed


Took me awhile to wrap my head around this (no pun intended) Carolina Sweet Tea at work Less head more kick in the tail.
I believe Ed is referring to THE FACT that while Full length sizeing a case diligently you will indeed watch the the shoulders move forward in measurment.
By constricting the body of the brass( this happens first as first contact between die and brass) the brass itself has nowhere else to go but push the shoulders forward.
Its a small sweetspot that lets the contienous measureer know they're about to contact the shoulders.
If your not carefully/slowly setting up a FL die for .001"-.002" bump with constant measurments you may never witness it.