I set my 280ai (unformed norma 280) with a 160gr pill over a light load (38gr imr4895) about .005-.006" into the lands (as referenced by the split case method). My question is,..that after reading some of the fireforming advice posted here,..am I far enough into the lands to get my brass growth from the neck and not from the case head area?

Thanks

The real purpose of seating into the lands is to prevent the primer strike from shoving the cartridge forward. Any contact should be enough but .010" or even .020" wouldn't hurt anything.

Bob338,..I have to use SOME, but not a lot of pressure closing the bolt on these,..which lets me know they are into the lands fairly well. Do you think I am doing OK with these? The shiny area on the 12 already fired appears up at the neck/shoulder area,..which I assume is an indicator of the brass flow being in the correct place???

Thanks

I tried that method of fireforming for my 338-06 AI, but gave it up promptly. Even when I left the bullet minimally seated and forced it the rest of the way into the case while chambering it, I still got head separation marks. I just don't think there was/is enough neck tension to resist the force of the firing pin.

Of course, this was in a mauser action, so your rifle might have a different strength firing pin spring. You might get away with fireforming this way with no troubles - I coudn't, though. Now I neck up to one caliber larger (.358") and then back down in the right die to set the shoulder right where I need it.

If this method is working for you, it doesn't matter how far into the lands the bullet is seated. As long as it is firmly in contact, you will have the needed pressure to push the shoulder out. maxman

I think you're doing fine from your description. As I said earlier, all you are trying to stop or slow down is the case being moved forward by the primer strike.

I also agree with Maxman to a point. You CAN increase your neck tension plenty, to prevent the case going forward. If you measure a case at the neck before seating a bullet and measure it again after seating, if the difference is .003", it's just not likely the case is going forward. There just isn't enough momentum in firing pin strike to seat the bullet deeper.

I think what Maxman has discovered is that it's really pretty hard to blow out the shoulder without stretching the body. I've not really looked into what happens with the improved cases but I did a bunch of testing on belted mag cases to try to determine if I could slow down the beginning of head separation. I tried fireforming those cases with bullets jammed into the lands while carefully marking the body at the shoulder with Dykem. I never could get the shoulder to fold "up" to extend the body of the case. I tried greasing them, greasing only a part of them, or as normal. In every case the body stretched.

I also tried creating the false shoulder by necking up, again using the Dykem at the shoulder/body joint. I could NEVER keep the cases from stretching in the body near the head, and I could NEVER see any part of the shoulder fold up into the body. I marvel at those who claim they have accomplished this. I've just never been able to do it nor have I seen any case that indicates this has occurred. I think your body will always stretch. The question is whether the stretch is confined to just one area near the head, or if the stretch is over most of the case body.

Well, if you read enough about AI calibers, you will find that if the new chamber is headspaced properly, a new factory case should provide proper fit without the necessity for jamming the bullet into the lands. The ordinary .280 headspaces on the shoulder, at the datum line, which is ordinarily about half way up the shoulder. That is for a normal chamber. The AI, when using the standard case headspaces on the junction of the neck and the shoulder, at least for that first shot. That is the way it is supposed to be.

Since I have more than one AI rifle, I will tell you that I do jam my bullets into the rifling for the first shot, quite tightly, and it works well.

Your real problem is using a mild load to fire-form. You ordinarily do not need to load down when fire-forming an AI caliber. After all, a .22-250 AI will fire max factory loads without any trouble, and they are loaded pretty hot.

Use a medium-heavy bullet with a moderate powder like 4895, with the bullet seated well into the lands. You pretty much have that part. But you need more powder to get this to work. Typically I go to the standard cartridge loading data in a good book and pick a load by going about half way between the lowest starting load and the top max load. Say, about 5% under max or so. Remember, the standard cartridge will be expanding in the fire-forming step and gain a little in case capacity.

With this method, I lose very few cases and most of them are from bungling the loading process to get everything exactly right.

Look at your primers when they come out after being fired. There should be no protrusion of the primer, from edge-to-edge, above the case head. Do not use the firing pin dent to judge this. If there is pressure enough to give you no primer protrusion, you have a good case forming load.

Have fun, be safe. Geo.

What about annealing the neck and sholder area before fireforming? Wouldn't this make a softer area that would expand and deform first? I'm in the process of makeing a 3200Hawk ish with a surplus 8x57 barrel on my VZ24. I'm planning on useing some LC 30-06 brass. I was thinking about useing a casefull of IMR5010 to fireform with. Would the compressed load help to push out the sholder upon fireing?
anybody know what the base to sholder measurement is on the 3200 Hawk?

Lar 45 I think you are planning on using a powder that is way too slow.I agree with what Geo has just explained. You are going to end up with cases that are not fireformed properly because of low pressure. I would also question the use of military brass.I suspect the main reason you are going to the 3200 Hawk is to increase case capacity and velocity.If this is the case why aren't you using the case with the largest capacity to start with? In most cases this is the Winchester case.I have filled std 06 cases with a fine ball powder full to the top of the neck. Win cases will hold between 2 and 3 grs more powder than most military cases. I've also measured the difference between std 06 cases and after they have been fireformed in my 30-06 Ackley.The case capacity is increased by about 3 grs in the fireformed case. So if I used military cases I would end up with fireformed cases with the same capacity as std Win 06 cases.

Lar45~
I've annealed before fireforming using a false shoulder and using a stout load of a fast pistol powder like Unique, stuffing the balance of the case with Cream O' Wheat or cornmeal, etc., etc. I've still NEVER seen the corner of the shoulder/body fold over. However, it may be a bit different for a radically improved case that is non-belted. There's only about a .025" gap between the chamber and the brass in my case whereas in the radically improved cases there is much more. I've just never had the opportunity to do any.

JustC,
If I had to recommend anything, it would be to not use an expander ball so you ended up with .003" - .005" tension, seat the bullet into the lands a minimum of .015", .020" - .025" wouldn't hurt, lightly lube the cases with crisco and use a medium load. All things mentioned will increase pressure and bolt thrust so don't over do things with a max load, shouldn't be necessary anyway. Compare headspace and case lengths to ones you know have been blown out all the way and I believe that's the best you could do to minimize stretching.

Bob338,
Interesting stuff, thanks for sharing your findings on that.

Thanks guys.