Rifle Case Sizing

[Bucksnort1]

While tackling the problem of finding the photo of the shortened bulge removing die, I tried an experiment.

As I said, I sold my 300 Weatherby loading equipment/brass but, I have the outer barrel of a 300 sizing die. I retrieved one of the few un-prepped cases I kept and full length sized it. I wanted to know if after resizing, would the case slide into the die all the way to the belt. It did not. The case stopped about .5" from the belt. I also have a few factory 300 rounds so I dropped one of those into the sizing die with the same result.

Why is this?

 

[nhyrum]

Spring back. After the sizing pressure is released, the brass "springs back" a few thousandths. Die manufacturers are aware of this and size the dies accordingly

Sent from my SM-G996U using Tapatalk

 

[rsnell]

Rifle dies for belted cases will not size a belted case just above the belt. To do this a die is available from Innovative Technologies.

 

[hooligan1]

Larry Willis die

I bought one, and the only use it gets is to use as a case guage to make sure my Forster Full Length sizing die is running right...
Like a Hundred dollar case guage......

 

[gwpercle]

Brass spring back . To go down where brass spring back is over come ... you get / use "Small Base" resizing dies . These size the case and last .5" of the case down more than normal ... when the brass "springs back " it is now back to factory new size .
Small base dies essentially over size them down ... they aid in semi-auto and punmp rifle operation , where extraction is limited , but do not aide in case life .
Gary

 

[Bucksnort1]

gwpercle, thanks for the information.

 

[Unclenick]

This thread describes using the Willis die nicely, if it interests you to own a weapon like this again.

I think in the other thread I described the die modification incompletely. If your cases run into the shoulder of a sizing die before it touches the belt, what you want to do is get a spare one and cut it off at the shoulder, so it won't stop the case from going further in. Once that has been done, then you can consider trimming the die mouth back as I described before if needed to eliminate mouth radius and hug the case down to the belt. Once you had used the modified die on the case, then you would follow up that operation by sizing with the intact sizing die to set the shoulder where you want it. You could sequence it the other way around, but be prepared the modified die will lengthen the brass by squeezing its diameter down. The brass has to flow somewhere. The main issue with this approach is it will narrow the 300 WBY cases to about 0.004" too much right at the belt. That's about how much diameter difference the SAAMI drawing says the chamber's side taper will have narrowed a half-inch forward of the belt. So you would probably want to get a small cylinder hone and open the trimmed case diameter four thousandths with it and then repolish the inside.

 

[Bart B.]

Updated

I forget who first cut off both ends of a belted magnum full length sizing die so only the case body between shoulder and belt would be reduced in diameter. That happened about 1960. It was used after traditional full length sizing with a gelded die with neck honed out to about .002" under loaded round's neck diameter.

That made regular full length sized belted cases test about half MOA at long range.

 

[Unclenick]

That's encouraging to hear. Makes it sound worth the trouble.