Fired brass headspace grows after FL resizing

[longrangeprecisionshooter]

Something I have thought about. When increasing the bump are you moving the the harder body/ shoulder junction back or just caving in the more movable flat shoulder more concave. In otherwords the corner doesn't get moved. I believe the bump gauge measures off the middle of the shoulder not the transition from body to shoulder? Are we just making the shoulder more concave? If your moving the body/shouder junction back the body must get a little bigger in diameter?

I am not an expert of this, but from my understanding, how FL sizing die works, it should move the body/shoulder junction back.
But correct me if I go this wrong.

Yes, I am aware the headspace is measured somewhere on the shoulder instead of the body/shoulder junction point. But for my measurement, I have to assume the FL sizing primarily push the body/shoulder junction point down and the shoulder remains the same.

From what I observed, I am guessing during the FL sizing process, if headspace is increasing, most likely the die is not pushing the brass shoulder in B area, and the brass's body/shoulder junction point has reached the highest point C inside the die, but not reach at the die's body/shoulder junction point A because die has firmly touched the shell holder at D, the brass can not go any further up. Therefore all the resizing changes would have to go to somewhere between C and A on the brass, eventually make the brass body longer, so does the headspace.





That's just my throughs on this. Not sure if it is right or wrong.

 

[longrangeprecisionshooter]

Go to a machine shop and have .005 - .010 ground off the bottom of your die. I've had to do this lately with Redding Type S full length dies. the comp shell holders won't do t!

That's what I thought I might need to do, cut the bottom of the die off a bit.

 

[Webster]

That's what I thought I might need to do, cut the bottom of the die off a bit.

Doesn't removing a few thou off the top of the shell holder do the same thing as removing metal from the die. Shell holders are inexpensive compared to die. A die would have to be put in a lath. You can sand a little off a shell holder.

 

[Fast14riot]

Doesn't removing a few thou off the top of the shell holder do the same thing as removing metal from the die. Shell holders are iexpensive compared to die. A die would have to be put in a lath. You can sand a little off a shell holder.

Yes, but I know several people who by default remove up to .030" off the bottom of Redding type-s diesright out of the box because they're usually a bit long. Just enough to remove the radius on the die mouth.

 

[BoydAllen]

Something I have thought about. When increasing the bump are you moving the the harder body/ shoulder junction back or just caving in the more movable flat shoulder more concave. In otherwords the corner doesn't get moved. I believe the bump gauge measures off the middle of the shoulder not the transition from body to shoulder? Are we just making the shoulder more concave? If your moving the body/shouder junction back the body must get a little bigger in diameter?

As the shoulder is moved back the top of the body goes into the outside of the shoulder and the top of the shoulder is forced into the base of the neck, and the neck gets longer, as does the overall length of the case, which requires trimming. If you back up to the part where I mentioned the top of the shoulder moving into the bottom of the neck, since the shoulder brass is usually thicker than the neck, particularly if the neck has been turned, this is how doughnuts are created.

One time, just for fun, I backed a one piece 22-250 die out until it just engaged the top two or three press threads. I was able to stroke a .30-06 case full the full stroke of the ram. Backing the ram down a bit, I turned the die down a bit and short stroked the press, repeating all of this several times until the die met the shell holder at the top of the rams stroke. I forgot to mention that I had taken the decapping rod and adapter bushing out of the top of the RCBS die. When I had finished I had a case that looked like a regular .22-250 case with a VERY long neck. Near the top of the ram stroke a Rock Chucker has a LOT of leverage. Naturally I made sure that the case was properly lubricated, The lube was the original RCBS based on lanolin. The point of the story was what I did was an extreme example of what happens when you bump a case shoulder back. I just bumped it back a lot farther. This was over 40 years ago.

 

[JFrank]

Mr. Guffey would say that it’s impossible to bump a shoulder using a die with full body support

Something I have thought about. When increasing the bump are you moving the the harder body/ shoulder junction back or just caving in the more movable flat shoulder more concave. In otherwords the corner doesn't get moved. I believe the bump gauge measures off the middle of the shoulder not the transition from body to shoulder? Are we just making the shoulder more concave? If your moving the body/shouder junction back the body must get a little bigger in diameter?

 

[Rick300]

I think I would send the die back rather than remove material off the bottom of the die. With the amount of error you are seeing, I wouldn't trust that any other dimension is correct. A new die is in order.

 

[rayporter]

shell holders vary enough that buying a few different brands may get you 6or 7 thou with out having to grind anything. grinding 8 or 10 thou off the shell holder is so easy and quick you can be up and running in an minutes. with 20 thou to go shell holders wont help fix this.

taking off more than 12 thou on the shell holder may get you a rim torn off the shell holder.

 

[10XSHOOTER]

I f you grind off the shell holder. The die is the same length . You still won't get the shoulder bump. The die needs to be shortened to get it down on the shoulder.

 

[alf]

One time, just for fun, I backed a one piece 22-250 die out until it just engaged the top two or three press threads. I was able to stroke a .30-06 case full the full stroke of the ram. Backing the ram down a bit, I turned the die down a bit and short stroked the press, repeating all of this several times until the die met the shell holder at the top of the rams stroke. I forgot to mention that I had taken the decapping rod and adapter bushing out of the top of the RCBS die. When I had finished I had a case that looked like a regular .22-250 case with a VERY long neck. Near the top of the ram stroke a Rock Chucker has a LOT of leverage. Naturally I made sure that the case was properly lubricated, The lube was the original RCBS based on lanolin. The point of the story was what I did was an extreme example of what happens when you bump a case shoulder back. I just bumped it back a lot farther. This was over 40 years ago.

More fun with a 30-06 case......

 

[alf]

I f you grind off the shell holder. The die is the same length . You still won't get the shoulder bump. The die needs to be shortened to get it down on the shoulder.

No.....

 

[Kracken McGraw]

Thanks a lot.

That's really helpful. I agree the description on Redding's website is really confusing.
I guess I am not be the only person thought it is going the other direction: Say my fired brass headspace is 1.193", if I want 0.002" bump when FL resizing, use the +0.002 shell holder from the set would by my choice and have a firm touch between shell holder and the die would get the job done with 1.191" headspace.
But it actually goes to an opposite direction, by using the +0.002 shell holder, I am kind of extending the headspace, most likely to 1.195", right?

The way I use the Competition shell holder with a die like yours is to put the .010 shell holder on the ram and raise it to top stroke. Screw your die into the press until it stops with contact on the shell holder, then screw down a additional 1/16 of a turn for camover and lock lock rig down there. Start replacing lower number shell holders till you find the one that gives your brass the closest measurement to your desired bump. Yes there may be a point that the brass lengthens( this has been talked about in past threads, and it happens). Go from the .010 down to the .002 then your regular shell holder would be last to give the most bump. I bet you find the desired bump around the .006 to .004 shell holder range.

 

[RussellJ]

From Mike Ratigan's book: Extreme Rifle Accuracy

From Tony Boyer's book: The Book of Rifle Accuracy

 

[Hohn]

Thank you.

Correct me if I got it wrong, using some sort of sand paper to reduce the depth between the top of the shell holder to the case head, just like how Redding competition shell holder works right?

It’s actually the opposite. The competition shell holders are progressively deeper than the standard 0.125” depth. They’re talking about sanding down the top of the holder to make it *shallower*.

Redding dies have more bump built into them (generally) so the assumption is that you’ll never or rarely need to have hard jam of die into shell holder, but you might want a bit more space. This extra space (in calibrated increments) is provided by the comp shell holders.

Personally, I find feeler gauges more than adequate for determining die setting.

 

[Ray123]

I was re-sizing some 4-5times fired 6 Dasher Alpha OCD brasses using a newly received FL sizing die, found the headspace grows about 0.0015-0.0020" after resize.
Fired brass headspace: 1.1935-1.1940"
After resizing headspace: 1.1950-1.1955"

1.My initial setup was, push the press handle all the way down(rise the ram all the way up) and screw the FL sizing die all the way down to touch the shell holder firmly. The decapping pin, expander and rod assembly is uninstalled.

2.Then I made some changes based on my initial setup, after lower the press ram down, I give the FL sizing die additional 1/4 turn towards the shell holder, in case there were some gap, now the shell holder and the bottom of the die are contacting tightly.
But, same result.

I repeated the above 2 methods using Redding competition shell holders, tried 0.002, 0.004 and 0.010 ones, all give the same result.

3. Based on my initial setup, I give the FL sizing die more adjustment going down, add from 1 full turn to 3 full turn step by step. At some point I wasn't sure exactly how much adjustment I made, probably around 2 full turns, it actually resized the brass with increased headspace from 1.1955" down to 1.1910". Unfortunately, I lost that point when I tried to back the FL sizing die up a little bit so it will size the brass to 1.192" and I can't find where that point is after.

Here is a photo of the brass after resized with black marker covers from neck/shoulder joint to the top of the body.
It seems there are contact/force applied on the body and the joint between body and shoulder, but no contact or only a minor scratch on the shoulder.
View attachment 1428268


4. Tried with a Redding Type S FL sizing die using my initial setup, it works as expected, sized brass to 1.192+/-0.0005" including those brasses I tried above with increased headspace.

As I suspect the new sizing die might have a longer body, I used depth rod on my caliper measured the depth from the bottom of the die to the brass body and shoulder joint point inside the sizing die, I got approximately:
1.100+/-0.005" for the new FL sizing die
1.070+/-0.002" for the Redding Type S FL sizing die
Seems there is 0.025-0.030" difference.

Does this sounds like a manufacturing issue with the sizing die? or something I did wrong. Thank you.

Had another guy having a sizing problem, asked what sizing die I used for 6 Dasher alpha brass, I told Wilson bushing FL die ...he ordered one and it solved his shoulder bump problem.
My fired cases, sized cased, and new cases are all the same at the shoulder, with the wilson die I bump em back, .0005" one half of one thousandths ...or zero. I chambered for the new Alpha brass as a go gauge and the go as the beginning of no go. The 40° shoulder doesn't move from new to fired, even with very hot loads.

 

[Old Navy]

Exactly.

Redding competition shell holders are taller for when the die pushes the shoulder down too far.

 

[longrangeprecisionshooter]

Had another guy having a sizing problem, asked what sizing die I used for 6 Dasher alpha brass, I told Wilson bushing FL die ...he ordered one and it solved his shoulder bump problem.
My fired cases, sized cased, and new cases are all the same at the shoulder, with the wilson die I bump em back, .0005" one half of one thousandths ...or zero. I chambered for the new Alpha brass as a go gauge and the go as the beginning of no go. The 40° shoulder doesn't move from new to fired, even with very hot loads.

Thanks.

Yeah, the Redding Type S FL sizing die works for my 6 dasher brass. Just the new FL sizing die from a different manufacture doesn't which surprised me with such a big gap inside.