Necking down .308 to .243

[Wm.Traynor]

A question has occurred to me that might be relevant
Do the necks have to be inside-reamed after reforming? Wondering if the re-sizing process thickens the neck and does it make bullet seating difficult or increase pressures?

[brett1868]

A few notes on annealing
1. There is no metallurgical purpose for quenching brass.
2. 650F-750F is the min / max temp required to anneal the necks otherwise pointless.
3. >450F at the base destroys the case.
4. Don't anneal pistol cases with a flame, it's dangerous due to the small case size and risk of softening the base.
5. Brass isn't the best of heat conductors, there isn't enough residual heat in the neck / shoulder to soak down and ruin the base once the heat source is removed unless you've over heated the shoulder. So the only reason to quench would be to cool the brass to enable handling.
6. In the absence of a proper temp indicator a dull red in a darked room is reasonably close.
7. Heat must be applied consistently around the neck / shoulder. Ideally the case should rotate in the flame from a controlled distance.

Tempilaq paints can be purchased online which "Melt" at a specific temperature. I use the 650F on the necks and 450F on the bases when setting up the Bench Source for new cases to calibrate the timer.

[Gwion]

Conducting any heat treatment purely on colour is a questionable practice. You say 'dull red', but what that looks like to you is completely different to how i will interperate it.

Mucking around with approximates might be ok if your hardening a knife in spring steel, the margin of error isn't going to blow up in your face... annealing cartridge cases, on the other hand......

Not saying some of you guys aren't getting it right with experience; this is just a word of warning to anyone thinking of trying it for the first time.

I say get some tempilaq, as Brett suggests.

[Lorgar]

7mm-08 is a round thats got some popularity here i dont no what you gain but i would have to read up on it

It's a bit more niche here in my experience.

I'm a fan though, I had a .308 and .243 a while back and have since replaced both with a 7mm-08 Tikka.

Great all purpose hunting cartridge for here in Australia, won't matter in the US but it's about the perfect spot to cover the game hunting laws here,

Mine shoots 0.4 MOA so is more than accurate enough for some target fun when I get to the range too.

[Lorgar]

A question has occurred to me that might be relevant
Do the necks have to be inside-reamed after reforming? Wondering if the re-sizing process thickens the neck and does it make bullet seating difficult or increase pressures?

The necks will thicken, you're not removing material by necking down the brass so it has to go somewhere as you reduce the neck diameter.

I've never bothered to measure or turn/ream the necks as I'm not chasing the kind of accuracy that requires fanatical case prep, and reloading is just a chore for me these days, not fun, so I wouldn't do it 'just because'.

Seating projectiles in .308 cases necked down to .243 you could feel it was tight as you raised the ram of the press, but didn't require excessive force and I never had one fail to seat.

Seating pills in cases necked down to 7mm I'd get the occasional tight one, but in most you wouldn't notice a difference at all. After I got my 7mm-08 I necked down about 400 308 cases and have reloaded them all several times without any problem at all.

[Wm.Traynor]

Thanks Lorgar

[Bills Shed]

Conducting any heat treatment purely on colour is a questionable practice. You say 'dull red', but what that looks like to you is completely different to how i will interperate it.

I say get some tempilaq, as Brett suggests.

Totally agree, I did just that for the first couple of hundred cases. After that my consistency got pretty good. Still use it every now and then though.

Bill

[bladeracer]

A question has occurred to me that might be relevant
Do the necks have to be inside-reamed after reforming? Wondering if the re-sizing process thickens the neck and does it make bullet seating difficult or increase pressures?

If you're necking down then the neck will get thicker. As long as it's not thicker than the gap between the bullet and the chamber throat then there's no problem.
If it's too thick to allow the neck to open up and release the bullet then pressure will increase significantly.
I doubt .308 down to .243 would be a problem with most brass but it's always best to check clearance before shooting the brass and turn the outside down if required.

[bladeracer]

7mm-08 is a round thats got some popularity here i dont no what you gain but i would have to read up on it

It's a bit more niche here in my experience.

I'm a fan though, I had a .308 and .243 a while back and have since replaced both with a 7mm-08 Tikka.

Great all purpose hunting cartridge for here in Australia, won't matter in the US but it's about the perfect spot to cover the game hunting laws here,

Mine shoots 0.4 MOA so is more than accurate enough for some target fun when I get to the range too.

I'm with you, 7mm-08 is pretty amazing.
Only downside is you can't run the really heavy hitters that you can in .308.
Heaviest .284" bullet I'm aware of is 220gn from Alco, but it requires a minimum 7" twist.
http://www.alcobullets.com/7mm-bullets/
Generally, you're probably not going to use anything heavier than 162gn for hunting.

[Lorgar]

Heavier pills is no concern for me at all.

I have two loads for mine. 120gr Ballistic Tips and 140gr Ballistic Tips.

120gr for when I'm on a friends property expecting foxes and fallow, and 140gr for the forest when expecting the larger deer species (and the odd goat).

I'm yet to find the deer that can shrug off a 140gr hunting bullet to the chest inside 200m.

If you really wanted to run something heavier you could use 150gr BT's, 160gr Accubond's, 154gr Interbond's, 162gr and 175gr Interlock's, 162gr SST's etc. etc.

With a quality projectile and taking sensible shots 140gr - 160gr is plenty.

To be frank, those 220gr Alco bullets seem ridiculous to me. If someone wanted to shoot 220gr bullets I think they've bought the wrong rifle going with a 7mm.

I note as well that the BC figures they quote along side most (all?) of those 7mm bullets are stated with velocities that exceed the ADI and other powder makers maximum load muzzle velocity by 150 - 200 fps so aren't even practical.

They're just about high Ballistic Coefficient bragging rights as far as I can tell

If I was building a long-range hunting or match rifle (where BC actually mattered), a 7mm Rem Mag with 180gr Berger's or Sierra's would do me just fine.