Chambering for 30 degree shoulder

[Lucky Shooter]

I'm reaming a chamber for a 221 FB with 30 degree shoulder----have the reamer
and matching GO GAGE from Pacific.

Would appreciate it if someone here would either confirm or correct my thinking.

The headspace for a new Lapua case----23 degree shoulder--- is .009" shorter than
the GO GAGE. Was hard to believe but repeated measurements have confirmed
this difference.

My understanding of this is that I have at least two options:

1) Set HS on the GO gage and seat bullet longer to fireform. This should blow
shoulders forward, slightly increase case capacity and slightly shorten the neck.

2) Set headspace on the case with slight crush fit. This should form shoulders to
30 degrees, ???? on case capacity and not shorten the case neck.

With no experience on shoulder angle change, and if my understanding is correct,
I'd choose not losing neck length over more case capacity.

Would appreciate some expert opinions.

A. Weldy

 

[Ramblerman]

I'm reaming a chamber for a 221 FB with 30 degree shoulder----have the reamer
and matching GO GAGE from Pacific.

Would appreciate it if someone here would either confirm or correct my thinking.

The headspace for a new Lapua case----23 degree shoulder--- is .009" shorter than
the GO GAGE. Was hard to believe but repeated measurements have confirmed
this difference.

My understanding of this is that I have at least two options:

1) Set HS on the GO gage and seat bullet longer to fireform. This should blow
shoulders forward, slightly increase case capacity and slightly shorten the neck.

2) Set headspace on the case with slight crush fit. This should form shoulders to
30 degrees, ???? on case capacity and not shorten the case neck.

With no experience on shoulder angle change, and if my understanding is correct,
I'd choose not losing neck length over more case capacity.

Would appreciate some expert opinions.

A. Weldy

No expert here, but to keep my brass sorta interchangeable between different rifles in same caliber, I have been known to use fired brass to set the headspace on a new chamber....so if it were me, I'd just just use the brass you got and chamber to that.... fireform and you're done. Just my $.02

 

[Dusty Stevens]

False shoulder

 

[DaveTooley]

Personally I would use the go gage. With the wildcat chamber you will be fire forming anyway. It will make any future barrels an easy transition . Also if you need more brass in the future a new lot may have a different length.

 

[skeetlee]

I never use the same brass in different barrels. in other words I always keep my brass dedicated to one barrel. when the barrel goes so does the brass. I would also recommend using a go gauge and not brass. to many variables to have happen and resulting in a chamber that's no in spec. safety first fellas. Lee

 

[mikecr]

No reason to go from wildcat to bastard out of it.
It does not appear that Lapua offers actual 221FB ammo (just cases), so there should not be a problem with ammo fitting.
I would set it up with your go gage, as normal. Inform the customer that they may need to tweak a fire-forming condition with Lapua cases (however they prefer). To check it, watch for it always, and have a basic plan in their log.

 

[Nightraider]

False shoulder

Just use a virgin case as the go gauge

 

[luckyshot52]

Lapua 221 brass should have the correct 30 degree shoulder. If u are using non fireball brass then you need to do as Dusty suggested. False shoulder. Look for instructions on doing Dasher brass for a good instruction. Not a wise idea to work to brass as a headspace gage.

 

[STS]

Personally I would use the go gage. With the wildcat chamber you will be fire forming anyway. It will make any future barrels an easy transition . Also if you need more brass in the future a new lot may have a different length.

Do yourself a favor and take Daves advise. In the long run you will be happy you did.