Still doubts about shoulder bump...

[Bora72]

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

 

[Richard Jones]

That would be too snug for me. I would bump it at least until the resistance is gone.

 

[1shot]

I prefer to have the slightest bit of resistance on a bare bolt. As you described, the weight of your finger. Neither of the two dimensions will cause you any problems. I hope this helps,

Lloyd

 

[Bora72]

Thanks guys for your advice, but especially for the quick replies!
While I was writing, I tried to see what happened to the bolt closing after switching to 0.262" expander.
The bolt closing, as I expected, became harder.
I assume it's due to the fact that when the expander passes through the neck and expands it, it also changes the shoulder angle. Can you confirm that the hardening of the bolt could be due to this?
At this point, I think that when I insert the bullet (.264"), the bolt will become even harder to operate.
Therefore, I think I'll have to go down to 1.4690" shoulder bump.

 

[Clancy]

I would bump another .001 or until the bolt closes freely. Bumping .002-.003 isn’t going to hurt your case life.

If your expander is changing the shoulder, you likely just need to lubricate it. Just a question here… but why is the expander needed if you had the die honed?

 

[Bora72]

Hello, if the inside of the neck is .260 and the expander is .262, when it expands, the geometry/angle of the shoulder also changes. I lubricate the inside of the neck with graphite. I use the expander because I want an interference of .262".

 

[William Vogel]

Having the die modified has changed the die. Your old dimension records are possibly void. The bolt lugs aren’t really designed to press the case into the chamber. It’s important to make sure they are well lubricated if you decide to run the brass at the dimension that requires a slight push to close. I’d adjust the die to get an easy close on the bolt. The brass may have a formation of a donut and the expander is shaping the inside of the neck at the donut outward which makes the neck/shoulder junction outside larger than the chamber. I’m not looking at the brass or measuring it. If this is happening and your bullet seats in the donut, it’s a dangerous bullet clamping situation that causes excess pressure to release the bullet. An easy check for donut is to find a gauge pin that is the size of the fired brass neck and if it fully inserts past the neck/shoulder, there is no donut. If it stops at the neck/shoulder junction, you have a donut formation and bullets should only be seated above this area.

 

[Bora72]

Is it possible that the modified die (by Forster) has different shoulder angle measurements?! The average cartridge case measures 1.4710" so 0.002" less should be fine if the die has dimensions and angles according to specifications, certainly not the neck diameter. If the die doesn't meet the CIP measurements, especially the shoulder angles, it's a real rip-off! With the FL bushing die I close at 1.4695" without any problems even after I change the expander to .2620".

 

[SKWERLZ]

That would be too snug for me. I would bump it at least until the resistance is gone.

i concur.

 

[jimmymac]

I would forget about trying to measure out to the 4th decimal place. If the brass is coming out of the gun at 1.471 you are not going to hurt anything by sizing them all to 1.468 or even 1.467 and call it a day. IMO, brass life will be good, accuracy will not suffer and your gun handling will be good.

 

[SKWERLZ]

I would forget about trying to measure out to the 4th decimal place. If the brass is coming out of the gun at 1.471 you are not going to hurt anything by sizing them all to 1.468 or even 1.467 and call it a day. IMO, brass life will be good, accuracy will not suffer and your gun handling will be good.

^^^
What I found is riding the edge with minimal
brass sizing is you get some snug, some jammed and some with some room.
Not an issue with short range accuracy but usually detrimental to ES.
ES is important for most of my shooting so that’s a factor I’m tuned in on.

Same with bullets, jam them well or stay off the lands enough to guarantee no touch accounting for bullet and oal variations.

 

[rwj]

I resize without expander ball.

If you’re full length resizing without the expander ball, then you’re expanding the neck in a separate operation. Simply switch from using the expander ball to a .262” mandrel to avoid distorting neck geometry.

 

[AlNyhus]

I would forget about trying to measure out to the 4th decimal place. If the brass is coming out of the gun at 1.471 you are not going to hurt anything by sizing them all to 1.468 or even 1.467 and call it a day. IMO, brass life will be good, accuracy will not suffer and your gun handling will be good.

This^^^^^

There's nothing to be gained by trying to bump cases back to some theoretical 'perfect' dimension. If great shooting guns depended on that.......there wouldn't be any great shooting guns.

Good shootin' -Al

 

[dellet]

Is it possible that the modified die (by Forster) has different shoulder angle measurements?! The average cartridge case measures 1.4710" so 0.002" less should be fine if the die has dimensions and angles according to specifications, certainly not the neck diameter. If the die doesn't meet the CIP measurements, especially the shoulder angles, it's a real rip-off! With the FL bushing die I close at 1.4695" without any problems even after I change the expander to .2620".

Did the honed die work before honing? You might not have tried.

If I understand the above post correctly, you are comparing brass sized with two different dies, in the same chamber. This will not work. It’s no different than expecting brass sized in one die to fit two different chambers.

The only way to do that is to loosen the tolerances. Both dies meet standards, the standards allow .010”, you are only allowing .001”. That is a problem, +/- .0005” will not be possible until you have a custom die made to match brass fired in your chamber.

 

[Coyotefurharvester]

With the bolt tension shown in the video, that typically(for me) is less than 0.002 from 0.001 bolt face clearance. So you can size for bolt clearance ( no tension on closing) to 0.002-0.003 bolt face clearance (hunting or field guns where dirt/dust contamination is possible). Of course you do need to factor in extreme variations in how individual cases size or check each case if wanting to run minimum clearance. Not sure what you mean by pressure issues, the load(charge weight) and bullet seating will be the same regardless of -0.002 to +0.003 bolt face clearance.

 

[DaveTooley]

Very often there is a mismatch in the radius at the neck shoulder junction causing a touch point. Not variations in shoulder angle.

 

[6MMsteve]

get the bump set for no resistance then enjoy the day

 

[Coyotefurharvester]

Dave, do you mean in the chamber or in the sizing die(or both)? Is this why sometimes just a very slight adjustment in die (in or out) results in 0.002+ movement in comparator numbers? Standard factory dies.

 

[Bottom Fodder]

Don’t over think or tec. It, if the bolt closes with very minimal pressure your good to go I druther have it A little tight than to loose

 

[DaveTooley]

Dave, do you mean in the chamber or in the sizing die(or both)? Is this why sometimes just a very slight adjustment in die (in or out) results in 0.002+ movement in comparator numbers? Standard factory dies.

Either can be off slightly. Sometimes you can mark up a case with a magic marker, then when you close the bolt it will leave a ring around the neck/shoulder junction. Probably happens more than we know.
Concerning a larger than expected change in the bump number. There is always spring back that has to overcome. Tap tap bigger bump then it moves.
I have never ever measured shoulder bump. The bolt handle tells all. I think in over 40+ years of shooting I've pulled the head off a case once. Have I seen case head separation approaching, yes and then taken those out of service. In todays world brass is cheap.
YMMV