Necking Down Proceedure

[n8ess]

I have been using Winchester brass in my 7mm-08, but I would like to try necking down some Lapua 308 brass. Could someone explain the procedure for me.

 

Cheers

 

Neil

[6mmBR]

Should be as easy as running a .308 case through a 7-08 full length size die.

I form 6x47 from 6.5x47 and it is just a one step technique as above.

Cheers

Dave

[Ronin]

You need a 308 die that accepts bushings (or a 7mm-08 die that accepts bushings)

 

Either will do.

 

I would make my own reducer bushing personally, but if I had to buy bushings I would look at the following:

 

Basic OD for 308 Win is .343"

 

7mm-08 OD is .315"

 

 

So you need to reduce the brass OD .028", which is a fairly big step.

 

 

I would consider using two stepped bushing sizes, (although I use one reducer I machined to reduce from .300WSM down to 7mm for my F class gun)

 

 

So use a .333" bushing then a 323" to get the initial step down, then a 7mm 08 die for the final re-size.

 

 

If your rifle has a tight neck you will have to consider neck turning prior as well (another process entirely)

 

Use a good resize lube such as Imperial Size Wax or similar to lube the case necks and put an outside chamfer on the case neck edge to assist entry into the dies bushing.

 

Go slowly too otherwise you will damage case mouths.

[Andrew]

Either of the above methods will work. I neck down 30-40 Krag Jorgensen case to 25 caliber in one pass using Hornady "One-Shot" lube inside and out. Marine PMI of this board can relate tales of making 6.5 Creedmore in which one brand of brass necked down fine, the other crumpled necks. I used to anneal .357 Magnum pistol cases and take them down to 25 caliber for my .256 Winchester Magnum in a single pass: A feat that annoyed and puzzled P.O. Ackley greatly. He repeatedly insisted that I (should have) needed a form-die set to get the job done. You just have to try it to see what's necessary.

 

Remember to go slowly and check your progress during the final stages for fit in your chamber. When you get everything fitting nicely it may be good to fire-form with the bullet seated into the lands so as to support the back end of the case against the bolt face and avoid any unintended stretching. ~Andrew

[Scotch_egg]

I only use remington 7-08 brass, however I know a few 7-08 shooters who neck down .308 brass in one step, through a full length die. If you have a full length die I would give it a go. Much less hassle and cheaper than a bushing die set.

[Chris-NZ]

Yup, single pass through an FL die.

You do end up with a shorter-than-std neck but it does grow over time

Chris-NZ