headspace

[mytwo60]

Hi,

So I was bored last night and didn't feel like working another 14hr day and decided to prep my brass for reloading. I full length size all my brass every time after each trip to the range.

I run my brass thru a body only die and measure the headspace to ensure they are within the limit of interest. However, after measuring several cases I have found some headspace are longer than others by as much as .002.

So, now I'm scratching my head. What could it be? The brass (I'm using Lapua)? The die (redding)? My measuring tool (hornday LnL Gage Bushing/Comparator)?

I'm thinking it could be the die but could also be the inaccuracy of the tool itself. So, what do you guys recommend? What is the best tool to measure headsapce? Oh and I use "Hornday one shot" to lubricate the brass and I always clean the die before each reloading. And yes, I made sure the die wasn't moving in the press.

[wbm]

.002? No big deal.

[Uncle Jack]

When resizing, is there any "spring" in the press? Is the die screwed down enough so that you get a good solid stroke?

uj

[mytwo60]

.002? No big deal.

No big deal as in it will not effect accuracy? Or this is expected tolerance/variation from sizing brass? Just trying to understand.

Yes, the die is screwed down tight but not overly tight.

I am working on a project right now where I want to be able to shoot the best group possible at 1000yds using the best loads with my cheap factory savage (minus the factory barrel). So far I have achieved average .5" groups at 100yds and last week I averaged .6" at 200yds. All 5 shot groups, btw.

My goal for next month is to shoot .75" avg groups at 300yds. So I am looking at other areas with respect to reloading that will help me achieve this 300yd goal.

I am taking small steps now so please don't overwhelm me with the 1000yds shooting tips yet. ;D

[wbm]

Let's start at the beginning. First, what are you shooting? Second, why do you full length resize your brass after each shooting session?

[358Hammer]

Once I have a case fire formed to a chamber I never size the body again. In fact my neck sizer is well off the shoulder junction.

Unless you have a chamber that is too long, either use a neck sizing die or move your die out away from the shoulder half a turn and I think you will be fine. Cases fired in a precision chamber will pretty much always remain the same size.

Well used hardened cases will tend to get brittle. Actually that isn't totally true as I have seen cases do what you are indicating right out of the new container. Some shoulders will size down and some will spring back from memory or other reasons.

No clue about your measuring techniques. A 2 thou difference can very easily be made in technique or equipment.

Neal

[RWO]

Anneal your cases and they will be much more uniform when they come out of the body die.

RWO

[scratcherky]

Try using lube on the inside of the case mouth. This will prevent the expander ball from pulling the case shoulder back.

[mytwo60]

Anneal your cases and they will be much more uniform when they come out of the body die.

RWO

Yes, I need to try this. I have done a couple of experiments tonight and noticed changes in the HS with various ways of resizing the brass. Annealing will be another experiment I need to try.

I will post my findings soon. The initial experiment is very interesting and I think most will find it useful. ;D

[mytwo60]

Once I have a case fire formed to a chamber I never size the body again. In fact my neck sizer is well off the shoulder junction.

Unless you have a chamber that is too long, either use a neck sizing die or move your die out away from the shoulder half a turn and I think you will be fine. Cases fired in a precision chamber will pretty much always remain the same size.

Well used hardened cases will tend to get brittle. Actually that isn't totally true as I have seen cases do what you are indicating right out of the new container. Some shoulders will size down and some will spring back from memory or other reasons.

No clue about your measuring techniques. A 2 thou difference can very easily be made in technique or equipment.

Neal

Hi Neal,

And you assume that by neck sizing only that the HS is the same with all the FF brass? Have you actually measured the HS from case to case? I am almost certain they will differ. This is why I FL all my brass to ensure they are all the same. Well at least that is the idea.

[mytwo60]

Try using lube on the inside of the case mouth. This will prevent the expander ball from pulling the case shoulder back.

Well I use Hornady one shot at a 45 degree angle so some of lube will get inside of the neck. But we are talking about a step before sizing the neck by using a body die only and measuring the HS after that.

[mytwo60]

Let's start at the beginning. First, what are you shooting? Second, why do you full length resize your brass after each shooting session?

Well my goal is to see how small of a group I can shoot at 1000yds with my "cheap" factory savage rifle minus the factory barrel. I FL all my brass to ensure they are all the same dimensionally. Also, I've heard the BR guys FL all their brass as well. Not saying this is the right or best thing to do but they must be doing something right. ;D

[trappst]

Error in tool, spring back in brass, and technique can all affect it.

Are you cleaning off the lube prior to measuring? Is the lube being applied the same to every case? Are you using the same amount of force to size each case?

Lots of factors come in to play here. Size it, load it and shoot it! ;D

If your load is good, you'll see more results on the target with practice and wind reading skills.

Lots of info on long range shooting/reloading techniques in the articles section over at 6mmbr.com