Problems necking up/down Lapua brass to 7mm?

[mattri]

Looking at building a 7m-08 AI and using either Lapua 308 necked down or Lapua 260 necked up. Has anyone had any experience doing this? Not planning to turn necks, keep things as simple as possible.

 

[ShootDots]

In either event, you WILL get a small "bulge" at the juncture of the neck and shoulder. The further you go up or down, the larger that bulge. If not turned off, it will go into the inside of the case as that dreaded "doughnut".. So you say you are not going to neck turn... Well in that case you need a LONG enough freebore to keep the bullets you are shooting WELL above the neck / shoulder junction!..

 

[lurcher]

I have a standard 7-08

norma 7-08 brass seems pretty good I used it, once I ran out I neck turned some lapua .308 and it worked fine but was a little on the short side.

It was suggested to me on here that it is probably best to sharpen up the shoulders with a .308 non bushing full length die and turn on a .308 mandrel and then neck down and fire form with bullets seated into the lands (I necked down then turned on a 7mm mandrel)

As i have used the brass I sized by shoulder bumping with a redding body die and neck sizing with a lee collet die with a washer over the top so I only sized the top 3/4 of the neck in the hopes of avoiding any donut-related issues seems to work fine in a factory chamber

really norma brass is way less hassle I will go that way again next time I buy brass. Actually for a factory-chambered hunting rifle I should be less OCD and just buy winchester 7-08 brass

 

[ShootDots]

IMHO whenever you neck down you should ALWAYS use a "non-bushing" "regular" die. You also need a "better than normal" outside neck chamfer on the case.. This will cause the case to "find it's way" into the die properly..

 

[BradY]

I neck 308 lapua palma cases to 260 in one go. Works ok with plenty of lube. But going to 7-08 first is alot easier. Before you build the rifle, neck down a 308 case to 7mm with a standard 7-08 FL die and plenty of imperial sizing wax in and outside of the neck. Then seat a bullet. Add 4 thou to that number and that will be the neck diameter for your reamer.

When necking down/up I feed a neckturn is a good idea especially into the shoulder to stop donuts from forming. But if you run a no turn chamber then you may end up inside neck reaming and need custom sized reamers made to suit fired brass. Neck turning isnt a bad thing. 100 cases, neck turning gear, a few beers and a game of football on TV.

 

[mattri]

Interesting replies, thanks.

 

[Jay Christopherson]

In either event, you WILL get a small "bulge" at the juncture of the neck and shoulder. The further you go up or down, the larger that bulge. If not turned off, it will go into the inside of the case as that dreaded "doughnut".. So you say you are not going to neck turn... Well in that case you need a LONG enough freebore to keep the bullets you are shooting WELL above the neck / shoulder junction!..

This is not my experience - you will need to account for "doughnuts" if you are necking up to 7MM (into the thicker shoulder). Easily prevented ahead of time by skim turning your necks down into the shoulder. If you are necking down, you'll be fine.

Personally, I prefer to neck down when possible

 

[ShootDots]

In either event, you WILL get a small "bulge" at the juncture of the neck and shoulder. The further you go up or down, the larger that bulge. If not turned off, it will go into the inside of the case as that dreaded "doughnut".. So you say you are not going to neck turn... Well in that case you need a LONG enough freebore to keep the bullets you are shooting WELL above the neck / shoulder junction!..

This is not my experience - you will need to account for "doughnuts" if you are necking up to 7MM (into the thicker shoulder). Easily prevented ahead of time by skim turning your necks down into the shoulder. If you are necking down, you'll be fine.

Personally, I prefer to neck down when possible

Necking down is easier or should I say "can be easier".. If you use virgin brass, that needs to be fireformed before it reaches it's full length by "growing in the shoulder area several thousandths" and neck that down, you WILL get a slight bulge at the neck shoulder junction. The reason for this is that the F/L or Neck Sizing die will not reach all the way down to that junction til after it's fireformed. That bulge needs to be turned off or it can become a doughnut. Now if you use say already fireformed 6.5 x 47 Lapua brass and then neck it down to 6-6.5 x 47 Lapua you will NOT get a bulge because the virgin brass has reached it's full fireformed length and the sizer die can reach down to where it needs to..

 

[Jay Christopherson]

In either event, you WILL get a small "bulge" at the juncture of the neck and shoulder. The further you go up or down, the larger that bulge. If not turned off, it will go into the inside of the case as that dreaded "doughnut".. So you say you are not going to neck turn... Well in that case you need a LONG enough freebore to keep the bullets you are shooting WELL above the neck / shoulder junction!..

This is not my experience- you will need to account for "doughnuts" if you are necking up to 7MM (into the thicker shoulder). Easily prevented ahead of time by skim turning your necks down into the shoulder. If you are necking down, you'll be fine.

Personally, I prefer to neck down when possible

Necking down is easier or should I say "can be easier".. If you use virgin brass, that needs to be fireformed before it reaches it's full length by "growing in the shoulder area several thousandths" and neck that down, you WILL get a slight bulge at the neck shoulder junction. The reason for this is that the F/L or Neck Sizing die will not reach all the way down to that junction til after it's fireformed. That bulge needs to be turned off or it can become a doughnut. Now if you use say already fireformed 6.5 x 47 Lapua brass and then neck it down to 6-6.5 x 47 Lapua you will NOT get a bulge because the virgin brass has reached it's full fireformed length and the sizer die can reach down to where it needs to..

You are making a lot of assumptions there. My experience does not match your statement. I'll leave it there, the OP can try whatever he likes.

 

[scpaul]

It's my understanding that one of the strong points of Ackley Improving a case is that you can use the original round(in this case 7-08)fire it in the improved chamber and it reforms itself.If you already have 7-80 unimproved cases it isn't supposed to require a full-house to do the reforming.Check w/other older loaders & see if I'm remembering right! Sometimes I get C.R.S. (can't remember stuff) Paul

 

[ShootDots]

Just "improving" a case is as easy as pie.. However, I do not just put factory ammo in the improved chamber and fire. I load and seat the bullet into the lands to hold the case against the bolt face to get proper headspacing, as it were, in the newly fireformed case..