Thread: Headspace variation after sizing

Just looking for some insight.

I'm sizing once fired Hornady brass with a Forster FL sizer. Using a Lee hand press.

I'm getting more variation in the shoulder length than I think I should.

Aiming for 1.553". Half size to that length and others come out at anything down to 1.550 even down to 1.549 in one case.

Trying to keep the lube and press action consistent. Measuring shoulder length with a Hornady comparitor.

Is that kind of variability common? If not it's probably the hand press eh?

Yep, the Lee hand press will actually flex and stretch under pressure.

Are you measuring the cases before sizing to confirm the hand press is actually bumping the shoulder back ?

How are you measuring the headspace ? Hornady shoulder comparator in a vernier caliper ? Do you have a flat anvil on the base side or just the vernier blade ?

Hi EBF. Yes pre-sizing the cases average 1.5549 ranging from 1.553 to 1.556. So we're bumping but not consistently.

I can't find any relationship between starting length and finishing length. It's not like the long ones stay long.

I wondered if sizing wax build-up in the die was causing it so cleaned it and swapped to oil. But same results.

Yes. Hornady shoulder comparitor in vernier calliper against flat anvil edge of moving blade. Have tested the measuring set up for consistency and its sound.

Sweet, sounds like the hand press is flexing. Try the die in a solid bench press and see what the results are.

Post them here, interesting thread

Thanks. I have a proper press just haven't mounted it. Will do this weekend. The take away is the variation is not normal. Thanks a tonne.

Using a Co-Ax press, Redding FL die, Hornady comparator and anvil, I got 6mmPPC cases at .330" dia on shoulder measuring from 1.1555 to 1.1565" (5 cases)
For the 7mm08 (Redding FL) at 0.400" dia, 5 cases ranged from 1.6280 to 1.6285". These were a bit tight to chamber. Before sizing they had been 1.6265 to 1.6275 so they were getting longer when sized !
Then I shortened the length and got 5 ranging from 1.621 to 1.622. This 0.006" made them chamber nice and easy.

So a total range of 0.001" seems achievable on a good bench press with an average operator.

My 7mm08 and .270win all range within a 0.001" ES prior to and post full length sizing (0.002" shoulder set back) using RCBS dies. So a range of 0.004" does sound off, especially with a Forster die. Must be the hand press to blame!

Best get that bench press mounted ASAP or have a play with some old cases to find out how much pressure to get consistent results on the hand press.

You guys are legends thanks for the help.

You could be getting spring back with some of the cases try annealing that may even out the spread.

As discussed I mounted the single stage press and went back to square one and trying to be more accurate with everything.

Rem 700 in 6.5 Creedmoor .....

Pulled the firing pin and ejector from the rifle bolt this time so I could feel for ideal headspace without interference. 1.555 and I can barely feel the bolt locking in. 1.556 and I can feel it. 1.557 and I'm applying a little pressure to close the bolt and at 1.558 its uncomfortably tight. So I'm thinking 1.555 would be a good place to be with the resized brass.

As a point of reference the Hornady factory round measures 1.553 before firing.

I pop the Forster FL die into the press and screw it down until it touches the shell holder. I back off the lever and screw the die down another 1/8th of a turn.

I've deprimed with a deprimer die and lubed the cartridges with One Shot.

Unsized the 50 once-fired cases average 1.5547 with a spread of .007. I give them all a run through the press trying to be consistent in pressure and timing.

Afterwards the average length is close to 1.556, which I can work with. But the spread is .006. Longest cartridges are 1.558, which I really can't use.

I give all the longer ones another run or two through the die. I get the average length down to 1.5555 for the 50 shells. But the spread is .005. Topping out at 1.558 still.

9 of them, so 18%, are in the 1.557, 1.558 area which is longer than I'm prepared to work with.

I'd love to be the guy bumping my shoulders back by .002 like the text books says. But I need some consistency first eh?

Any suggestion please?

Lee collet die.

What make of press?
My Lee anniversary runs about the same variation (004-006) you are getting.

The Lee collet die will not bump the shoulder back, just make the neck smaller.

Originally Posted by wsm junkie

What make of press?
My Lee anniversary runs about the same variation (004-006) you are getting.

This one...Breeck lock I think...