Forming .260AI from .308,.243, etc.. Dies needed & Process?

Hey all... Wanting to know what the process is and what dies are needed to form 260AI from other cartridges, NOT fire forming, I got that part..... I know that a "false shoulder" is needed when forming AI's, (BillPa hooked me up w/ that invaluable knowledge, thank you Bill), so I have a good understanding of that I think, and I've been reloading for 10 years or so but not much forming yet. Is it best to take the new .308 & FL size it in a 308 die or just skip that and size it in a 7mm-08? Or just a body die? Before necking it down? These are the things I don't know. What's the cheapest way around the die question? How do I not buy 30 sets of dies?, etc... Can you just buy a different decapping assy, with a taper mandrel in .277 for the "false shoulder" and put it in a 260 die or a 7mm-08 die? Lot's of questions I guess? ::)

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Originally Posted by L.H. Clark

Hey all... Wanting to know what the process is and what dies are needed to form 260AI from other cartridges, NOT fire forming, I got that part..... I know that a "false shoulder" is needed when forming AI's, (BillPa hooked me up w/ that invaluable knowledge, thank you Bill), so I have a good understanding of that I think, and I've been reloading for 10 years or so but not much forming yet. Is it best to take the new .308 & FL size it in a 308 die or just skip that and size it in a 7mm-08? Or just a body die? Before necking it down? These are the things I don't know. What's the cheapest way around the die question? How do I not buy 30 sets of dies?, etc... Can you just buy a different decapping assy, with a taper mandrel in .277 for the "false shoulder" and put it in a 260 die or a 7mm-08 die? Lot's of questions I guess? ::)

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LOL...me again!

One invaluable tool you might want to consider is Dave's (CH4D) neck bushing die, about 60 bucks with one bushig.
http://i37.tinypic.com/124tzis.jpg http://www.ch4d.com/catalog/images/StdBNS.gif

http://www.ch4d.com/

Now you can play some games with it. One obviously, necking brass down in one or more steps with only the appropriate sized bushing(s). You can also remove the bushing and use the decapping rod with a sized button to neck up brass, again in one pass or with different buttons in multiple passes. If you use a well undersized button you can punch out the spent primers and neck size in one step without over working the brass. I turned the button in my picture to .190", one size fits all! ;D

With that arrangement you can neck up, neck down and stop short of the junction to form a false shoulders if need be....on the cheap.! To top things off for only 11 bucks a pop for a bushing you can neck size all your other stuff. It beats the snot out of $75 or more per cartridge. Oh, and by the way, the floating bushing doesn't pull the necks out of alignment. Of course it doesn't straighten them either! ;D

After you have some brass formed send a few pieces to Dave and have a custom FL die made.

I made all but one or two of the bushings and my own floating expander die and tapered mandrels, but lacking the tools to make them the floating bushing die with some additional parts is a good less expensive way to accomplish the same thing, only cheaper.

Bill

I made 260AI brass from .308 Lapua as follows: Size brass to .284 w/ a 7-08 die then to .260 w/ a .260 Rem die. Then fireform. I trim and clean up the necks and we are good to go.

You are going to have to REALLY watch the neck thickness if you use 308 brass necked down. Better to neck up with 243 brass.

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Originally Posted by savageboy

I made 260AI brass from .308 Lapua as follows: Size brass to .284 w/ a 7-08 die then to .260 w/ a .260 Rem die. Then fireform. I trim and clean up the necks and we are good to go.

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Too many dies and steps. ;D

This is for a "normal" 260 and NOT a 260AI.

I Just use a 260 body die and jam it all the way up with the 308 brass. Then run it thru a neck only die and you're done. No need for a 7-08 die. I tried this and the fire forming rounds shoots in .5s. I don't see any problems using this method for 260AI as well.

Make sure to trim the necks though.

I found that it is much easier and somewhat cheaper to use .260 brass to start with. Full length size, trim and fire form.

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Originally Posted by JCalhoun

I found that it is much easier and somewhat cheaper to use .260 brass to start with. Full length size, trim and fire form.

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Yes just neck size lapua 260 brass, jam a cheap bullet in the lands with a middle to upper end load and shoot and done!

The way i did it was this. I formed my cases out of 30-06 lake city match cases. The first thing I did was measure my chamber length and then cut the necks off the 06 cases just above the shoulder and anneal. I then ran them though the .308 die and ended up with a .308 case with a really long neck. I then trimmed the necks off to 20 thousandths longer then my chamber length and then ran them through the .260 die. I then adjusted my die and crimped the necks over a little so I could get them to chamber. I used the cream of wheat fire forming method of using 26 grains of HS-6 pistol powder covered by cream of wheat and topped off with crisco. During the fire forming process the necks will shrink down from the 20 thousands to long to about 5 thousandths. I then run them through the .260 Ackley die and then trim with a modified lee case trimmer to my exact case length. This process my be a little long but you only need 3 die sets and this eliminates some of the throat erosion problems that happen when forming ackley cases from a .308 or .243 due to the shrinking of the necks during the fire forming process. Hope this helps.