Magnum case sizing

[Ackley Kid]

I recently started using some magnum cases ( 300WSM , 7Saum , 7PRC ) for f class shooting .
What amount of sizing is required at the base to keep cases running smooth for numerous cycle’s?
As the case heads are substantially thicker than the 473 case heads , is more sizing required here than say 284 win ?
Current die set ups give give around 1 thou sizing , is this to much or not enough ?
Running ADG and Lapua brass in PRC , ADG in SAUM .
Any thoughts on this would be appreciated.
Thanks in advance

 

[Preacher]

With the correct die there is no more problem sizing than any other case..
.001 is fine as long as it's kept clean...

 

[ronemus]

The only problem is when you have a sloppy chamber that allow excessive expansion, then try to use the brass in a barrel with a minimum chamber; a small-base die may then be needed to sufficiently size the brass.

 

[SKWERLZ]

I size my 7 saum and 338 edge cases down 1-2 thou.

I’ve gotten excellent life out of the adg 7 saum cases that way.
A good lube and some dwell time in the die is your friend.

 

[JFrank]

We run a 270 wsm at about .0015-.002 at the .200 line, it seems to cycle well.

 

[46and2]

We run a 270 wsm at about .0015-.002 at the .200 line, it seems to cycle well.

That is the critical place on non-belted magnums. Regardless of the shoulder bump, if this area isn't sized enough you'll have chambering problems.
Same way on belted magnums at about 5/16" ( above the belt) on belted magnums.

 

[Ackley Kid]

Thanks guys .
On the Saum we tweaked the base on the reamer to accommodate the ADG brass as it’s a little smaller , and I had dies made .
On the PRC I went the other way and used Alex Wheelers AW2 body to accommodate off the shelf dies .
WSM is in Limbo as brass is impossible to find at present time …. Only had 20 pieces of Norma and had dies made for this one as well .
Currently have two cycles on Saum , and PRC brass and haven’t has issues yet , but time will tell ….. headed home from work this week and plan to get some more testing done .
Appreciate all the information !

 

[Straightshooter1]

I've only had my 6.5 PRC for about a year and have 4 firings on both Lapua and some Hornady brass. I've been using a Forster FL sizing die and so far have not had any issues. The brass measures .532 after firing and will still chamber. After sizing, the brass measures at .531"; so I'm getting that .001 sizing.

 

[gunsandgunsmithing]

I've only had my 6.5 PRC for about a year and have 4 firings on both Lapua and some Hornady brass. I've been using a Forster FL sizing die and so far have not had any issues. The brass measures .532 after firing and will still chamber. After sizing, the brass measures at .531"; so I'm getting that .001 sizing.

It'd scare some people to know how much smaller the sizing die is to yield .001" after springback, though. Probably about .006"! The bottom of the brass is thick and hard compared to the shoulder area and it resists sizing quite a bit. You've really got to be pretty aggressive with it to yield that much. I don't do many big guns but on ppc/br cases, I like a chamber reamer to be spec'd about .003 larger than the die itself. That yields me about .0015 at the shoulder and about .0005-.0006 at the .200 line. You can cast the die to get those numbers but Kiff at PTG is a wealth of knowledge in that area as they supply many of the die reamers to Redding and other die makers. He's very familiar with die and chamber reamers as well as the spring back. Whatever you think of PTG, he's still a big player in our game and we use a lot of his products, even if indirectly.
As I understand it, Remington owed him $$$ when they went under, to the tune of multi million dollars. That's how he's coming up with all those remington actions and such. He's getting that in lieu of cash as the court allows them to distribute. BTW, he's got some really cool and rare items right now. Some of which, I never new were made.