Headspace Woes

[lancetkenyon]

Before you actually FL sized the brass, did you pop the primer and check to see how much your headspace grew with the once fired compared to virgin brass? I have found MOST virgin 28Nos brass to be fairly close to correct shoulder length compared to once/twice/three X fired cases. Very little growth after once fired. I have a LOT of experience with the 28 Nos.

There are other cases that grow a TON, like belted magnums. Not uncommon to see .014-.021" shoulder growth from virgin to even once fired.

 

[Doom2]

It's possible any or all of the items mentioned can affect your datum dimension. You are overthinkng the whole issue. Setting for 0.002" bump is not going to give you 0.002" every time. If you expect this then you will be disappointed. If you can measure or shoot the difference that +/-0,002" will make in precision or standard deviation I would love to see the data. Yes there are people who show it. Or they think that they see it but it's in the noise.

 

[Hikinghunter]

Ahhhhh, if ES was that simple... Lots of variables go into finding a good load and ES is just one of them and lots of variable go into finding a low ES as well.

Sure. Im asking about drastic inconsistencies, though.

Look at it the other way around. Say you have a load worked up that's shooting, say, single digit ES and 1/2moa with your 3x fired brass. Then you get a batch of new brass with the same headstamp. You load it with the same primer/bullet/powder charge. All other things being equal, Would you typically expect the new brass to shoot 2MOA with an ES of 40 just because it's not fire formed yet?

I'm sure if you mixed your new and 3x fired brass, you'd get a lot of inconsistency since you'd have different case volumes. Not what I'm talking about. I'm asking if load development with new cases is worthless, cause the fire-formed cases that are a few thou longer will have such a drastically different velocity that the harmonics of your barrel are completely different, requiring not just a small adjustment of powder charge to compensate but a complete re-do of load development.

 

[lancetkenyon]

Sure. Im asking about drastic inconsistencies, though.

Look at it the other way around. Say you have a load worked up that's shooting, say, single digit ES and 1/2moa with your 3x fired brass. Then you get a batch of new brass with the same headstamp. You load it with the same primer/bullet/powder charge. All other things being equal, Would you typically expect the new brass to shoot 2MOA with an ES of 40 just because it's not fire formed yet?

I'm sure if you mixed your new and 3x fired brass, you'd get a lot of inconsistency since you'd have different case volumes. Not what I'm talking about. I'm asking if load development with new cases is worthless, cause the fire-formed cases that are a few thou longer will have such a drastically different velocity that the harmonics of your barrel are completely different, requiring not just a small adjustment of powder charge to compensate but a complete re-do of load development.

I have not had THAT big of differences from virgin to fired brass loads in 28Nos. But, you need to check brass volume between brass lots. Nosler and Hornady have both done some crazy things with brass lots. Nosler switched their brass for the 28 Nos a few years ago. Brass weight differed as much as 25gr, meaning internal volume changed significantly. Plus, the brass they use for factory ammo and the brass they sold for handloaders was vastly different volume. Like not even interchangeable.

Hornady changes brass so often, it is crazy. When they first started making brass for the 6.5SAUM, there were three distinct batches. All varied by huge amounts for brass weight and case capacity. Again, making them not interchangeable. Same with the 6.5CM brass. And now some 7PRC brass.

 

[Buckskinner]

Sure. Im asking about drastic inconsistencies, though.

Look at it the other way around. Say you have a load worked up that's shooting, say, single digit ES and 1/2moa with your 3x fired brass. Then you get a batch of new brass with the same headstamp. You load it with the same primer/bullet/powder charge. All other things being equal, Would you typically expect the new brass to shoot 2MOA with an ES of 40 just because it's not fire formed yet?

Absolutely not, If you are getting that drastic of a change from new vs fired formed brass there is something very wrong somewhere in your system either gun or load. Most of my rifles show very little difference on paper with new vs fired brass and a slight difference in ES. Although I don't chase ES once my load is established.

 

[Hikinghunter]

I have not had THAT big of differences from virgin to fired brass loads in 28Nos. But, you need to check brass volume between brass lots. Nosler and Hornady have both done some crazy things with brass lots. Nosler switched their brass for the 28 Nos a few years ago. Brass weight differed as much as 25gr, meaning internal volume changed significantly. Plus, the brass they use for factory ammo and the brass they sold for handloaders was vastly different volume. Like not even interchangeable.

Hornady changes brass so often, it is crazy. When they first started making brass for the 6.5SAUM, there were three distinct batches. All varied by huge amounts for brass weight and case capacity. Again, making them not interchangeable. Same with the 6.5CM brass. And now some 7PRC brass.

Nice. Thats really helpful.

I'm using Peterson brass, so hopefully more consistent. How would you measure case volume of unprimed virgin brass?

 

[Hikinghunter]

Nice. Thats really helpful.

I'm using Peterson brass, so hopefully more consistent. How would you measure case volume of unprimed virgin brass?

Or would you bother, if your goal is just a half-decent sub-moa load?

 

[Doom2]

Sure. Im asking about drastic inconsistencies, though.

Look at it the other way around. Say you have a load worked up that's shooting, say, single digit ES and 1/2moa with your 3x fired brass. Then you get a batch of new brass with the same headstamp. You load it with the same primer/bullet/powder charge. All other things being equal, Would you typically expect the new brass to shoot 2MOA with an ES of 40 just because it's not fire formed yet?

I'm sure if you mixed your new and 3x fired brass, you'd get a lot of inconsistency since you'd have different case volumes. Not what I'm talking about. I'm asking if load development with new cases is worthless, cause the fire-formed cases that are a few thou longer will have such a drastically different velocity that the harmonics of your barrel are completely different, requiring not just a small adjustment of powder charge to compensate but a complete re-do of load development.

Absolutely not, If you are getting that drastic of a change from new vs fired formed brass there is something very wrong somewhere in your system either gun or load. Most of my rifles show very little difference on paper with new vs fired brass and a slight difference in ES. Although I don't chase ES once my load is established.

The first thing you should do is check the volume of the fired/resized brass versus the new unfired brass (Google it). You can also check weight within a lot but with different lots of brass that is not a good measure. It is possible there is enough difference to take you away from your node. 2MOA at 100yds is a lot and would likely indicate a barrel time effect. 2 MOA at 300yds would be a barrel time and velocity effect.

 

[cabelasken]

I once bought a 270 win , an old xtr that had a lousy cut chamber. Brass lasted just one or two reloads and anything approaching a max load was just a shotgun pattern on paper. But if load 3 to 4 grains under max, bug hold groups were achievable. After initial firings, factory brass was already damaged - with the bright ring at the base of head. It did kill game however and if you stayed under 2750 -2775 FPS with a 130 grain pellet, it was extremely accurate. I achieved 7 straight one shot kills before I gave up.

 

[Carlos88]

Sure. Im asking about drastic inconsistencies, though.

Look at it the other way around. Say you have a load worked up that's shooting, say, single digit ES and 1/2moa with your 3x fired brass. Then you get a batch of new brass with the same headstamp. You load it with the same primer/bullet/powder charge. All other things being equal, Would you typically expect the new brass to shoot 2MOA with an ES of 40 just because it's not fire formed yet?

I'm sure if you mixed your new and 3x fired brass, you'd get a lot of inconsistency since you'd have different case volumes. Not what I'm talking about. I'm asking if load development with new cases is worthless, cause the fire-formed cases that are a few thou longer will have such a drastically different velocity that the harmonics of your barrel are completely different, requiring not just a small adjustment of powder charge to compensate but a complete re-do of load development.

It's not worthless. Any day at the range is better than a day at work.

Reloading isn't an exact science. There are processes that are absolute (decapping, resizing, seating, etc.). By absolute I mean the bare minimum to make the rifle go bang.

You will never get to a zero deviation on anything that involves different ogive lengths, different powder lots, internal case dimensions, flash hole size and location, etc. Match primers are those that have the most "consistent" priming compound and even they will vary.

Establish a starting point and eliminate one thing at a time. Don't try two, one. Finally, are your reeloads straight?

 

[243winxb]

Redding competition shell holders- Start with .010" see if sized brass fits rifle.

When fired brass gets hard to chamber, go down 1 size to .008" and so on, till all chamber.

Or feeler gauge to set die.

 

[MagnumManiac]

This is my advice I tell everyone.
Fire your cases 3 times with only neck sizing, regardless of what it is, measure it EVERYWHERE, not just the shoulder. THEN size it to get your .002" bump. Measure the case everywhere again and see how much you are sizing the case at the .200" line up from the base.
As an example, my 300RUM brass still doesn't match the chamber, I fired a single piece 3 times to get a benchmark, bolt still doesn't close firmly, so I know another firing is required. What is impressive is that none of the measurements on the body are in-excess of .003", which means my brass won't be overworked causing incipient head separations over many sizings. People size too much without realising it too often. Brass needs to stabilise and minimal sizing is the key to this.

Cheers.

 

[HandgunHTR]

Wondering if this is unusual. I'm using a Lyman t-mag 2 press, which is admittedly not the best. It does have a pretty fair amount of cam-over.

Any thoughts on how to get better consistently?

I didn't see this mentioned anywhere else in the thread yet. While the T-Mag makes it easy to swap from cartridge to cartridge, or from sizing to seating, it has quite a bit of flex in it.
Do this. If you can, have someone else pull on the handle and size a piece of brass. While they are doing that, you look at the turret from the side with your eye even with the turret. You will see it flex.
I started with a T-Mag as well, but have switched to a standard single stage for precision reloading. As long as you continue to use the turret press, you cannot expect to get consistency in sizing. Seating is usually fine as the amount of force required to seat bullets is minimal.

 

[Mike6158]

^^ That was a good catch. I use a Forster CO-AX and didn't consider the press that he's using.