Old Fired Cases Won't Chamber in New Barrel

[Ross1147]

If you FL resize and it still doesn't chamber you'll need a small base resizing die. I had this happen in a custom 300 WSM a while back. Even went as far as contacting Defiance thinking something was wrong with the action. While I was on the phone with them I started measuring everything and found out the base was too larger even after FL sizing. I just trashed the brass and started over…in those days brass was plentiful and it wasn't worth the cost of buying a new die set. Today, I'd buy the dies.

 

[L.Sherm]

DO NOT just keep turning the die down untill they chamber. Before you know it you will start having case separation from bumping the shoulders back so far.
Get a small base die or body die

 

[hawk-i]

So you have cases that were fired in the old barrel. And now, even after sizing, they don't fit in the new barrel?

Old barrel had a worn out out of spec chamber, new barrel has a tight chamber.

The easiest way to tell is to Mic. the resized brass that won't fit the new chamber...I had a new barrel put on a 300PRC that had the same problem and it ended up being the new chamber wasn't cut correctly.

 

[19 Badger]

Will a factory round chamber in it? If so, chamber it and shoot it to get a good idea of your chamber size from base to shoulder datum. It will probably take a couple firings to completely fireform to your chamber. I would do this before I started running your sizing die in blindly and possibly bumping the shoulder back to far and setting yourself up for a possible case head separation in the future. After reading further, I believe L. Sherm is correct.

 

[Lone Hunter]

In a print look at the .200 line. In brass that was fired in another rifle most times every chamber is a little different. You might get some Redding Competition Shell Holders and try to size the base out with them. Maybe they could get you down far enough to get it sized. There is .002 difference between the shell holders. From .002-.010

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What L Sherm said is GOOD advice also.. Redding also states you can remove the bushing and internal parts you can use it as a body die.

Type S – Full Bushing Die

Full length resizing while maintaining exact control of the case neck is often desirable in one operation. The new Type S - Full Length Resizing/Bushing Die accomplishes this task with the precision you would expect from Redding.

• Uses the same interchangeable bushings (.001" increments) as those used in our bushing style neck sizing dies.
• The adjustable decapping rod allows you to adjust the bushing position, sizing only part of the neck length when desire d .
• Concentricity is enhanced by the ability of the bushing to self-center on the neck of the cartridge case.
• All Type S (except 17 and 20 Cal.) dies are supplied with both the standard size button and a decapping pin retainer for the advantages and versatility described under our Type S - Bushing Style Neck Sizing Dies.

Note: By removing the bushing and all internal parts, the Type-S full bushing die may also be used as a body die.

All dies are supplied without bushings.

 

[L.Sherm]

Your still gonna have to be careful using a body die, they bump the shoulder too.
It might get you more sizing on the .200 line though. A small base die is really the answer.

 

[L.Sherm]

Cape Coves advice is probably the best, use a 300 Rum die and you might have to take some off a shell holder but atleast you won't be bumping the shoulders

 

[59FLH]

He bumped the shoulder .002" relative to the OLD chamber, how do any of you know more sizing of the case is to much for his NEW chamber and it's going to cause separation?

I would recommend screwing the die down until brass fits the NEW chamber or like was mentioned earlier, set the FL size die according to the mfg instructions. Size a few pieces, if they fit load them, fire them, measure them, then proceed.

 

[Mike D Texas]

Do you have a way to measure base to shoulder datum like a shoulder bump gauge? It could be that the chamber shoulder was further forward on the older chamber than the newer one. I wouldn't instantly assume that it's at the case web area until you check the shoulder datum.

 

[L.Sherm]

I used some new cases to make the loads I used to break in the new barrel. I also used these newly fired cases to measure the headspace of the new barrel. This morning I FL sized a few of my old cases and bumped the shoulders .002" back.

 

[bballard]

I had this same situation with a new cooper 6mm Remington.......basically my new cooper has a very tight chamber. I could not get FL sized brass to work if they were already fired in other 6mm's. I bought a small base die to remedy this problem, but did not use it. Instead I just bought some brand new brass and will only use it in that rifle. I believe either solution will work......

 

[Willys]

I had to make my own small base die, got a cheap full size die, cut top off at the shoulder, sanded .010 off a shell holder . Golden. May or may not work for you.

 

[azarcher10x]

Like others have said, you need a small base die. Thay do nothing to the shoulder, and will size the base. I had a similar issue after neck sizing only on some 300 RUM. Difference was, they didn't want to eject after firing. My first thoughts were over pressure, but the weren't loaded hot at all. It only started after the second loading. Basically, the brass lost it's "memory." Even after FL sizing, there was still an issue. I ran all my brass and loaded rounds through a small base die, and problem solved! The brass needs some room to expand and retract on firing. If you're starting out where you're having trouble getting them to chamber, it's only going to be worse if some manage to chamber.

 

[RidgeTop]

Get a Full Length Small Base die