Still doubts about shoulder bump...

[Bob3700]

Oh, I forgot, I anneal the necks after every shot.

The annealing should provide consistency of shoulder set back.
The resizing process reduces the brass dimensions overall so it fits the chamber. With ur stripped bolt, set ur die up to get the desired effort on bolt closure. Take a resized case and using a sharpie, color the case up. Chamber and extract the case, u will see where the case is actually touching the chamber. That may shed some light on where the bolt effort is coming from.

 

[ELR LVR]

get the bump set for no resistance then enjoy the day

Agreed here
I played with slight resistance upon closing bolt for awhile
I dont think it gains us any further brass life
and only increases bolt lug wear if anything
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the problem was if there was ever a case that maybe was .001" over
I couldn't close the bolt or it got stuck etc
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Best to have the bolt close with no resistance to ensure you can close and fire all loaded cases
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Now, I really like knowing for a fact, the bolt simply falls easily and I can fire every round I've loaded
the necks will split way before anything else happens

 

[JFrank]

Hi,
You're right about the springback, so I'd add that if I measure 1.4710" headspace, it will definitely be 1.4715" or even 1.4720".
At this point, setting a 1.4690" headspace on the die should give me excellent bolt closure, but that's not the case.
So the hypothesis that you support, that it could also depend on the body taper, is plausible...
It seems strange to me, however, that there is a difference in dimensions and proportions between an FL die and an FL Bushing die from the same manufacturer, especially from a specialized company like Forster.
I haven't tested the repeatability of the measurements yet because I'm still trying to find the right die setting and I don't have many fired cases to resize.
Okay, regarding the case life reasons.
To measure headspace, I use the Hornady .375 comparator, which doesn't seem to be CIP-compliant.
The SAAMI or CIP measurements are like a love manual; they're useful as long as you can read them. Once the light goes out, everyone makes do as best they can...
I put a drop of silicone oil on the bolt lugs.

If you size a case back to where a stripped bolt falls without resistance then go .002 additional set back you’ll likely never have a problem cycling rounds after ignition.
With regards to spring back… if I had a week to think up a list of stuff to worry about , SB would not make the top 50.

 

[kevinbritvec]

Hello every one,
I have recently recived honed die from Forster for my 6,5x47 Lapua.
Now I'm setting for shoulder bump.
My fired case at middle load are 1.4710"/1.4715"(high load).
Normally I set shoulder to bump at 1.4690"/1.4695" for bolt falling without resistance(firing pin and ejector removed).
At 1.4700" the Bolt don't fall down free but the force for closing it are very low, I gently push It down with the finger.
For brass life are 1.4700" bump suitable or I can have pressure issues and so are better that I set shoulder bump at 1.4690"/1.4695"?
I resize without expander ball.

Regards

I really try to avoid any interference fit when closing the bolt. .0015" to .002" clearance is my goal.

 

[Bora72]

If you size a case back to where a stripped bolt falls without resistance then go .002 additional set back you’ll likely never have a problem cycling rounds after ignition.
With regards to spring back… if I had a week to think up a list of stuff to worry about , SB would not make the top 50.

Thanks for the reply and suggestions. I think I'll try to get the bump down to between 1.469 and 1.480.
First, however, I'll try to verify in some "homemade" way whether the measurement from the body portion to the shoulder joint of a fired case and a refired case are equivalent.

 

[Bora72]

I really try to avoid any interference fit when closing the bolt. .0015" to .002" clearance is my goal.

This has always been my goal so far...

 

[ELR LVR]

If you size a case back to where a stripped bolt falls without resistance then go .002 additional set back you’ll likely never have a problem cycling rounds after ignition.
With regards to spring back…

if I had a week to think up a list of stuff to worry about , SB would not make the top 50.

Listen to this ^^^

 

[jimmymac]

Please can you explain me better?

Thanks

Go back and read post #10. There is zero benefit by concentrating on the smallest shoulder bump you can get away with. It is just that easy and your target will never know the difference.