Time for a small base die?

[mattri]

Interesting situation- here are the dimensions-

New unfired brass:
Base to shoulder= 1.6255-1.626
Diameter at .200 from base= .4635

Fired cases:
Base to shoulder= 1.626
Diameter at .200 from base= .4685-.469

If I set the die (Forster FLS) to bump the shoulder back .002 the bulge at the base is still pronounced enough to cause a hard bolt closure. If I set the die to size the base diameter down to .467 the bulge is reduced enough the bolt closure goes away but the shoulder ends up pushed back to 1.6215-1.622.

My concern is that in order to size the bulge out of the base the shoulder needs to be pushed back to the point that accuracy suffers or ignition issues arise.

Thoughts?

 

[JMayo]

Calaber ?
Ring die fixes the .200 line.
Some parent case dies will size down farther with out bumping sholder.

 

[mattri]

308 Win. Have to look at a ring die, hadn't heard of it before thanks.

 

[stevenpoplin]

havn't heard of a ring die either, Do Tell

 

[JMayo]

@Uthink Uknow is who i got it from.
With my shell holder it sizes right to the very edge of the extraction Grove. With a competition shell holder I think it would go a little past the groove.

 

[JMayo]

See the color change down. That much was sized down. .4685
Pm him.

 

[Dusty Stevens]

Is this a factory chamber? Sounds like you should send some fired cases to whidden and get some dies that work

 

[Uthink Uknow]

As our ring dies are a straight wall die they size only the base of the Cartridge. They do not touch the shoulder. Pictured is my ring die and a 30BR case that has been sized with the ring die.

 

[Coyotefurharvester]

308 win minimum chamber @.200 is .4714 if I'm reading drawing correct. So you are already sizing smaller?

 

[mattri]

Yes, perhaps an undersized chamber but getting hard bokt closure until base diameter is appr .4675-.468

 

[K22]

The hard bolt closure got my attention. I'll offer my experience with a similar condition, but I don't know if it will help you but here it is.

While I've never had 308 reloads that developed bulges in the base, I've had a fair number of 223 Rem cases exhibit this condition. However, none of them exhibited hard bolt closure or extraction.

First issue I'd consider is how hot is the load? I ruled it out in my situation since the load was well within published data and I did not encounter any other signs of pressure. Also, in my situation, the vast majority of cases were unaffected. So, have you ruled out too hot of a load?

The small base die caused other problems and didn't fix my situation. You can try it, but I'd only do one or two cases, shoot them and decide if this is the fix. In my cases sized with a small base die, excessive expansion occurred so I can't recommend this as a fix.

Sierra wrote a paper of this condition and I believe it was posted in the Daily Bulletin. If I remember correctly, the bottom line was that this occurrence is not unusual even with loads that are not at the pressure limit. However, the hard chambering in your situation needs to be addressed.

In my case, the rifles where this was happening were examined by my rifles smith who determined that the chambers were slightly out of round. He explained the reason that not all cases were affected were due to differences in the metallurgy of the cases. I continued to use the cases without any ill effects but again, I did not have any hard chambering or extraction issues.

 

[stevenpoplin]

so the sized case is dificult to chamber aftersizing, and I assume before sizing, so how dificult is it comming out of the chamber? bolt lift harder than usual? Having to beat on the bolt handle with a hammer to open bolt? I don't think you would do that but had to ask.
BTW what manufacturer of brass? New factory rifle? make of action? barrel, reamer?
Someting abnormal is going on here obviosly, and a small base only die may fix your dillema, but not solve an underlying problem. Like the chamber expanding abnormally for some reason.
Before I purchased a specialty die, I would barrow a small base 308 die and try that first. I have one I would loan you if you want.

 

[243winxb]

If I set the die to size the base diameter down to .467 the bulge is reduced enough the bolt closure goes away but the shoulder ends up pushed back to 1.6215-1.622.

The .004" set back will work fine. The shell holder contacting the bottom of the fl die may work as well. . Try it and measure set back. Maximum set back should be around .005"

If you want longer case life, get a bushing die that doesnt over work the necks.

 

[stevenpoplin]

so if he bumps the shoulder back .002 from fired case size, case wont chamber. But if shoulder is bumped .004 or .0045 now base is sized enough... in .002 more than before? am I missing someting ?

 

[mattri]

Great replies- will try to address questions raised.

It would seem that when adjusted to bump the shoulder back .002 the die does not size the base enough to allow for smooth chambering- when the die is adjusted to size the base more it unfortunately also bumps the shoulder back excessively.

Rifle is a Rem 700 factory barreled 308.

Brass is weight sorted WW virgin, then measured after 1x.

Initial chambering of virgin brass is smooth, extraction is not noticeably difficult.

Taking a fired case and trying to chamber without sizing results in difficult bolt closure.

A fired case that has been sized, but not enough to eliminate the bulge results in difficult bolt closure.

Load was nowhere near hot.

At this point the chamber is certainly suspect.

 

[Murray Brook]

Would you happen to have on hand another sizing die based on the 30/06 case like 25/06 or 270 or 30/06. If yes then try running your case all the way up in one of these dies till the base of the die is in sloid contact with the shell holder. This should size the .200 line and not affect your shoulder bump . Then use your 308 die to bump the shoulder. Might work.

 

[Dusty Stevens]

If it shoots good and you plan on keeping it a while id get a die made from whidden

 

[JMayo]

Just thinking out loud.
I pulled my 6ppc barrel back out & screwed it on after a year of 6bra.
My notes from then were good i thought ... Took ejector & FP off bolt.

Previously made ammo is really tight, hard bolt close. I Markered .200 line. It didn't show any scrub. (220 Russian)

I was thinking jaming to much bullet may be causing hard bolt close. Took a round apart, used the empty case and found it wouldn't chamber easily ..
Bumped back brass until it fit easy this raising the sholder #'s question.
I played with some cases and now i think i had sholder wrong. Bumping them .001 more gave just a little scrub .

Scratching my head on this one because i take barrels on and off. But i decided to go with changing my notes and bumping to a new #.
I suppose a go & no go guage would take out my confusion....

I don't know what die i might could use to size lower without hitting sholder.

 

[243winxb]

https://forum.accurateshooter.com/threads/harder-bolt-close-after-sizing.4057277/

To many new reloaders are running into a "bump" problem. Man made, most of the time. Like in the link.

Excessive shoulder set back is .010" or more. Then you will see case separations.

 

[Dusty Stevens]

Just thinking out loud.
I pulled my 6ppc barrel back out & screwed it on after a year of 6bra.
My notes from then were good i thought ... Took ejector & FP off bolt.

Previously made ammo is really tight, hard bolt close. I Markered .200 line. It didn't show any scrub. (220 Russian)

I was thinking jaming to much bullet may be causing hard bolt close. Took a round apart, used the empty case and found it wouldn't chamber easily ..
Bumped back brass until it fit easy this raising the sholder #'s question.
I played with some cases and now i think i had sholder wrong. Bumping them .001 more gave just a little scrub .

Scratching my head on this one because i take barrels on and off. But i decided to go with changing my notes and bumping to a new #.
I suppose a go & no go guage would take out my confusion....

I don't know what die i might could use to size lower without hitting sholder.

You could have set back your lugs, worn your lugs, press worn (if you just put a preadjusted die in), or the barrel shoulder could be seating different (most likely choice). This is why taking your best barrels off to save them for a big match never works out well.