Variation in headspace from FL resizing

[Mainer]

Question for those that check headspce on each case as you full length resize/bump shoulders. How much variation do you get?

Folks talk about bumping back .002" , but is that something that you verify by measurement, or do you randomly check a few and assume all are the same?

I bet if more folks checked each case as they full length sized them, they would be surprised by the variation in headspace that they are getting.

 

[Olen_4504]

mine are pretty damn consistent case to case.

what die are you using? what lube?

 

[Mainer]

mine are pretty damn consistent case to case.

what die are you using? what lube?

Sounds like we're getting the same results.

Mine are "pretty damn consistent " also.

 

[zacii]

I do a few cases at first, checking dimensions with a comparator. Once I see they’re all consistent I go through and resize the whole lot of brass that I’m working on. Through the process, I’ll check random cases, but I’ve never seen any variations in sizes to worry about.

 

[Olen_4504]

Sounds like we're getting the same results.

Mine are "pretty damn consistent " also.

i don't measure every. single. piece. but if i randomly grab 10 - they'll all be the same.

i will say - my new harrels die is much smoother and sizes much better than my old hornady die.

also with some lubes or if the case isn't lubed very well it'll kinda stick in the die and stretch back out when removing from the die.

 

[Mainer]

i don't measure every. single. piece. but if i randomly grab 10 - they'll all be the same.

i will say - my new harrels die is much smoother and sizes much better than my old hornady die.

also some if the case isn't lube very well itll kinda stick in the die and stretch back out when removing from the die.

I had some cases that were sizing hard while using Imperial sizing wax. Switching back to RCBS lube 2 cured that.

 

[Olen_4504]

I had some cases that were sizing hard while using Imperial sizing wax. Switching back to RCBS lube 2 cured that.

i use imperial for onesy/twosey stuff. but for large batches i use lanolin/alcohol mix. works fantastic

dump all the brass in a ziploc bag. two sprays. slosh the brass around. dump out onto towel and let alcohol evaporate. good to go!

 

[FishDr]

I use the alcohol / lanolin as well. For smaller groups I'll use the Hornady OneShot spray.
Generally, when I check them all (I check everything on my 260), I'll be w/in +/- .0005. But that is checking with calipers and very subjective to feel and inconsistent pressure. You have to be consistent in the measuring process.

 

[Steel head]

lube or brass hardness variations can make shoulder bump vary with hardness variations being the bigger offender.
Used to see it a lot before I started annealing.
I just spot check every 10-15 and it’s within a thou.

 

[shoot4fun]

There are a multitude of things that can cause variation in what I refer to as the amount of shoulder bump.
Often overlooked is proper lubrication
Annealing (or not) and inconsistent/incorrect annealing
Flex in the ram of your press
Dwell time when case has been fully inserted in the die
Measurement process
Mine, and I will check virtually every case, is always consistent. If not, that is when I start to root out the cause. Same with seating or, for that matte, any part of the process.
Do you deprime brass before measuring? The primer can cause you to get bad readings and leave you with, maybe not inconsistent bump but, bad data and too much shoulder bump.

 

[AKMarty]

I just started reloading 6.5 CM. This is my first cartridge that I have loaded for long range precision. Past reloading experience is with .338 WM, .375 H&H, .44 Mag.

I was checking my chamber dimension CB to the lands. I removed the firing pin and plunger type ejector (Tikka Tac A1). I neck sized (bushing type sizer) and mandrel expanded the neck before seating a bullet long. At first the long loaded cartridge would not chamber(expected) and I would re-seat the bullet deeper. The idea being that when the bolt drops I will have reached the CBTO at the lands. Several pieces of once fired brass with a bullet seated, would not close easily even when short of factory CBTO. As I investigated why I was having this problem I discovered what seems like large variations in the headspace . Factory ammo headspace on the Hornady 147 ELDM was 1.552". The once fired brass was varying from 1.552" to 1.555". I could always close the bolt but the 1.554"+ was more firm.

Is this normal?
Do you FL resize, bump the shoulder, or just neck size? Why?

Thanks ahead of time.
Marty

 

[spife7980]

I just started reloading 6.5 CM. This is my first cartridge that I have loaded for long range precision. Past reloading experience is with .338 WM, .375 H&H, .44 Mag.

I was checking my chamber dimension CB to the lands. I removed the firing pin and plunger type ejector (Tikka Tac A1). I neck sized (bushing type sizer) and mandrel expanded the neck before seating a bullet long. At first the long loaded cartridge would not chamber(expected) and I would re-seat the bullet deeper. The idea being that when the bolt drops I will have reached the CBTO at the lands. Several pieces of once fired brass with a bullet seated, would not close easily even when short of factory CBTO. As I investigated why I was having this problem I discovered what seems like large variations in the headspace . Factory ammo headspace on the Hornady 147 ELDM was 1.552". The once fired brass was varying from 1.552" to 1.555". I could always close the bolt but the 1.554"+ was more firm.

Is this normal?
Do you FL resize, bump the shoulder, or just neck size? Why?

Thanks ahead of time.
Marty

Your bolt should fall free of interference from the brass. If your brass is interfering try coloring it in sharpie to tell when you touch the lands.

 

[phlegethon]

Your bolt should fall free of interference from the brass. If your brass is interfering try coloring it in sharpie to tell when you touch the lands.

Your brass shouldn’t be touching the lands! You can use a similar method to find shoulder bump but the linked video is for bullet seating depth.

 

[spife7980]

Which is what they guy that bumped the thread was asking about in relation to interference from brass. So thanks?

Your brass shouldn’t be touching the lands! You can use a similar method to find shoulder bump but the linked video is for bullet seating depth.

 

[A&8's]

I started prepping my cases on my 650 a couple months ago. One Shot is my preferred lube. FL/Bump is 1st die. Due to shell plate load, my 1st two and last two cases varying a tad. I normally prep 100-200 cases at a setting, so I just add the 1st and last 2 get cycled in with the next batch. Other than those few, others stick right at .002" bump (+/- .0005".)

Also, be sure to wipe your brass when checking for bump. And lube again when adjusting. Ex: lube, bump, wipe, check. If more bump is required, lube again, bump, wipe, check. Then when desired bump is achieved, check 3-4 rounds to make sure everything in the die lockup is seated before running a hundred of them.

 

[Dthomas3523]

Your bolt should fall free of interference from the brass. If your brass is interfering try coloring it in sharpie to tell when you touch the lands.

Yep. Setting die up to fall free will give you room on both sides. If it doesn’t bump enough, bolt will still close with slight tension. If you bump too much, it won’t be enough to have excessive headspace.

 

[Dthomas3523]

Your brass shouldn’t be touching the lands! You can use a similar method to find shoulder bump but the linked video is for bullet seating depth.

Just the wrong video. Wheeler makes one showing shoulder bump as well.

 

[Dthomas3523]

Question for those that check headspce on each case as you full length resize/bump shoulders. How much variation do you get?

Folks talk about bumping back .002" , but is that something that you verify by measurement, or do you randomly check a few and assume all are the same?

I bet if more folks checked each case as they full length sized them, they would be surprised by the variation in headspace that they are getting.

I set mine up for the bolt to fall free. Then I take that measurement and make sure I’m within a thou or two across about a 10% sample of my brass.

I don’t care if it’s .001 or .003 bumped back from fired brass. Just like I don’t measure lands anymore when adjusting seating depth during the course of a barrel’s life.

 

[morganlamprecht]

if you want to take the majority of the variation out, get the redding comp shell holders that are set up to bottom out on the die

for a typical bump set up the die doesnt bottom out on the holder...any variation in brass hardness/lube can cause small differences in how much of the presses mechanical slack is taken out at full stoke

In my experience it doesnt matter much, ive ran 10s of thousands of rounds without them and they shot fine, but getting the adjustable redding holders took almost all of the variation out

 

[AKMarty]

Your bolt should fall free of interference from the brass. If your brass is interfering try coloring it in sharpie to tell when you touch the lands.

Your brass shouldn’t be touching the lands! You can use a similar method to find shoulder bump but the linked video is for bullet seating depth.

I used the technique in this video for finding the lands.

No brass was touching the lands. Only the bullet engaging the rifling. The deceptive tightness while measuring the lands was from the headspace not the bullet.

So, do you always at a minimum bump the shoulder? I saw above all the factors that can influence the headspace, some I had never thought of. How often will you FL resize?

My primary objective right now is to have a consistent process.

Thanks for all the replies.

 

[Dthomas3523]

I used the technique in this video for finding the lands.

No brass was touching the lands. Only the bullet engaging the rifling. The deceptive tightness while measuring the lands was from the headspace not the bullet.

So, do you always at a minimum bump the shoulder? I saw above all the factors that can influence the headspace, some I had never thought of. How often will you FL resize?

My primary objective right now is to have a consistent process.

Thanks for all the replies.

FL resize every firing.

Size to the point where your bolt falls free with the ejector removed.

 

[AKMarty]

FL resize every firing.

Size to the point where your bolt falls free with the ejector removed.

FL resize every time...do you do this to be exactly consistent reload to reload? What do you see as the problem with bumping the shoulder and neck sizing only?

Last night I used brass that was 1.552" headspaced and the bolt would always fall freely if I was out of the lands. It wouldn't work with 1.554" or bigger.

 

[Dthomas3523]

FL resize every time...do you do this to be exactly consistent reload to reload? What do you see as the problem with bumping the shoulder and neck sizing only?

Last night I used brass that was 1.552" headspaced and the bolt would always fall freely if I was out of the lands. It wouldn't work with 1.554" or bigger.

Lands don’t matter. That’s the shoulders being too far forward in chamber not letting it close.

Neck sizing only literally does nothing. No accuracy improvement, no brass life improvement, nothing.

What I can do however, is be a problem feeding/extracting. And you never know when.

F/L sizing is more consistent, and have zero chance to fail.

 

[Brux]

Are you working with different lot numbers of brass? If so you will never get anything consistent.

 

[Deleted member 10043]

I neck size until they get a little tight than FL. I mean FL according to the standard die instructions. I don't waste time with bumping measuring and whatever.

 

[AKMarty]

Are you working with different lot numbers of brass? If so you will never get anything consistent.

Single lot#

 

[Mainer]

Are you working with different lot numbers of brass? If so you will never get anything consistent.

The brass I bought (Lapua from Brouno's) was not packaged with any thing that gave a lot number.