Trimming the bottom on the sizing die

[yew plucker]

I bought a 10 Short Action with a 4.27 screw spacing. I wanted to build a budget target rifle. I installed a Shaw .308 Varmint barrel. I set the headspace at a minimum. Virgin brass and unfired .308 rounds chamber perfectly. Some of the brass I sized, like 10% of it, chamber perfectly or with a slightly tight bolt. The rest won't chamber at all.

Setting the Die: I use a Dillon 550. I screwed the die down until it contacted the ram, then backed the ram down and turned the die another 1/8 to 1/4 turn, so that the ram actually cams over when fully raised. The brass is still at least .005 too long to the shoulder. I use a Dillon Headspace gauge to check and also attempt to chamber in my tight chambered rifle. Some of them won't size down no matter what, and remain fifteen thou too long, so I just chunk them. The ones which are close are so close that its a tease. Oh the frustration!

I finally got with a friend who has a machine shop. After comparing a factory unfired round, a military round, and a fired case which I sized, we decided to chuck up the die in his lathe and trim a couple thou off the bottom on the die. We tried .005 at first and decided to go ahead and take off 10 thou. When I sized a fired case after that, the Dillon gauge showed the brass going just below the upper step of the gauge and flush with the lower step cut. Perfect!

Moral here? Don't be afraid to make a correction. Fired brass has a certain amount of elasticity and some will spring back to former dimension even after your best attempt has been made to size within spec. In this case, going slightly below SAAMI spec with the sizing die caused the brass to size about right.

This worked for me. I can't say what will work for you. But if you have had the same challenge, trim that die!

Anyone else done this or similar? Discuss.

[CarolinaShooter]

I had a similar issue reloading 7mag. However it turned out I just wasn't pressing down hard enough when resizing. I was just about to shim my shell holder when I realized one of the pieces that would chamber looked slightly different at the shoulder. That extra pressure was needed to actually bump the shoulder.

[BillPa]

Speaking strictly rimless bottleneck cartridges the shell holder deck height ( floor to the top) determines how far a case can enter a die. The spec is .125" but I've checked some as short as .123" or a long as .126", even those made by the same manufacturer. Instead of shortening a die I surface ground some SHs for .115" deck height and use die shims. If I need or want more or less shoulder bump I'll use thinner or thicker shim under the die lock nut-ring to raise or lower the die in relationship to the SH without having to adjust it.

That setup also comes in handy when loading for multiple rifles chambered for the same cartridge. I keep a list in each die box which rifle uses which shim.

http://www.sinclairintl.com/reloading-equipment/reloading-dies/replacement-parts-amp-upgrades/skip-s-die-shim-kit-7-8-14--prod33197.aspx

Bill

[Robinhood]

I just back the barrel of .002.

[yew plucker]

I just back the barrel of .002

It isn't about one rifle. It is about making range pick-up or once-fired brass function in a tight chambered rifle. If factory ammo, and military ammo will chamber perfectly, I should be able to set the die so that any ammo I load would chamber also. I have a friend I load for and by coincidence his rifle has a custom Lilja barrel on it. His gun smith set the headspace tight. This also extends the life of the brass, all brass, shot in the rifle.

[CarolinaShooter]

Yeah the brass I resized had been fired in a factory 7mag barrel that had such throat erosion looking through the chamber was like looking down a rifled musket barrel. I had since installed a shilen match barrel so you can imagine why the brass wouldn't allow me to close the bolt and get stuck.

[LHitchcox]

A cheaper route would have been to take the extra off the top of the shell holder. It is easy to place it face down on a belt sander and let the belt dress off a bit of metal. shell holders are cheaper than dies if you overdo it too. The only times I have had to do that were with a .243 WSSM which has really thick brass that wants to spring back and on a .300 Ultra Mag. It is a good idea to mark the shell holder so that it isn't used for any other dies.

[Robinhood]

Anneal.


Because of this

brass that wants to spring back

[short round]

You cannot do the shell holder thinning procedure on Dillon 550, due to design.

[yew plucker]

Anneal.

Indeed.

[Twinsen]

You cannot do the shell holder thinning procedure on Dillon 550, due to design.

My Dillon 308 die requires a lot of cam over. I cannot do more than a slight shoulder bump.

I was thinking either buy a new die or shave the shell holder. I don't have it in front of me, but why could you not shave the Dillon shell holder?

[short round]

After giving some thought to the 550, it could be shaved, but you have four stations to deal with. It would be more involved than one shell holder & possibly involve a milling machine.

[yew plucker]

Seemed simpler to trim the die just a half a hair.

[Bunky-Shooter]

Easy fix !! Use a single stage press with Redding Competition shellholder set to bump shoulder back. The set comes with 5 shellholders in increments .002 to .010 that will decrease the case to chamber headspace. I have gone through this problem using once shot brass in 308 and 30-06.. This would be easier than trying to modify the Dillion 550. Once shoulders are bumped back put em back in the Dillion 550 and business as usual..

[eddiesindian]

I bought a 10 Short Action with a 4.27 screw spacing. I wanted to build a budget target rifle. I installed a Shaw .308 Varmint barrel. I set the headspace at a minimum. Virgin brass and unfired .308 rounds chamber perfectly. Some of the brass I sized, like 10% of it, chamber perfectly or with a slightly tight bolt. The rest won't chamber at all.

Setting the Die: I use a Dillon 550. I screwed the die down until it contacted the ram, then backed the ram down and turned the die another 1/8 to 1/4 turn, so that the ram actually cams over when fully raised. The brass is still at least .005 too long to the shoulder. I use a Dillon Headspace gauge to check and also attempt to chamber in my tight chambered rifle. Some of them won't size down no matter what, and remain fifteen thou too long, so I just chunk them. The ones which are close are so close that its a tease. Oh the frustration!

I finally got with a friend who has a machine shop. After comparing a factory unfired round, a military round, and a fired case which I sized, we decided to chuck up the die in his lathe and trim a couple thou off the bottom on the die. We tried .005 at first and decided to go ahead and take off 10 thou. When I sized a fired case after that, the Dillon gauge showed the brass going just below the upper step of the gauge and flush with the lower step cut. Perfect!

Moral here? Don't be afraid to make a correction. Fired brass has a certain amount of elasticity and some will spring back to former dimension even after your best attempt has been made to size within spec. In this case, going slightly below SAAMI spec with the sizing die caused the brass to size about right.

This worked for me. I can't say what will work for you. But if you have had the same challenge, trim that die!

Anyone else done this or similar? Discuss.
Good idea........if it works for you?.........run with it.
I thought about doing just that but never got around to giving the die to my buddy who has a lathe. I ended up shaving some from the shell holder.

[fgw_in_fla]

I'm a "shell holder shaver" as well although, there was a certain Lee .243 die that was not going to co-operate and had to be sent back to Lee along with a couple pieces of brass. They trimmed a few thousandths off the bottom and all was well.

Then I went out and bought a bunch of RCBS dies.
Lately the quality of Lee dies has gone down a bit.

[yew plucker]

[QUOTE]Good idea........if it works for you?.........run with it.
I thought about doing just that but never got around to giving the die to my buddy who has a lathe. I ended up shaving some from the shell holder./QUOTE]

It seems to work ok so far. Some 7.62 LC brass is too stubborn though. I chunk those in my recycle bin, to be sold for scrap. Better to get a few pennies for them. I wish I had a multi position hydraulic press where I could force that stretched LC brass back down to spec.

[arnie]

I have found that the shoulder sets back further when I roll my cases on a freshly lubed pad . As the lube goes away after more groups of rolling cases the shoulder sets back less .So if you have some brass that wont set back try more lube .