I have a forbes 25-06 that Melvin Forbes worked over with a new barrel
recently i noticed that one of the nickel cases i have been shooting in it had the nickel separated with a small line around the case, so i opened the case up to find the start of a case separation issue....to my knowledge these have only been resized in the collet die i have ...seems like this couldnt happen when using this die ....thoughts

Could probably chalk that up to a difference in chamber dimensions.

I think I have 7 different cartridges in Lee collets....never experienced that...some of my 6.5 Swede match brass has been fired 15 times. .308 Federal nickel, almost that many firings. Maybe something else is going on.

I don't see it happening because of the collet die, but I can think of it happening for other reasons. For example, how far forward did the shoulder of the brass move from brand new to the once fired state? Despite neck sizing, are you needing to trim the brass anyway now and then?

Sounds to me like chamber dimensions and shoulder on original brass.

Yep not gonna blame LCD for this one.

Likely brass stretching on first firing in that chamber. If you want to avoid it, you could neck down .270 brass in a full length 25/06 die and form a false shoulder so that it chambers with a slight crush fit. Neck is longer on .270 so you would have to trim it as well.

Could do the same with 25/06 brass by first necking it up in a .270 die then proceed as above.

John

Sounds to me it wasn't adjusted right.... I've had some case head separations lately on some PMC 223 brass...

Re adjusted the die and the problem disappeared.....

and 15 firings like my friend Flintlocke speaks of, Proper care, I get at least 3 times that number or more...

My preferred method of resizing a case, is the Lee Neck Collet Die and then a Body die, Anneal it each time, and show a little prudence on the powder scale, and one can get a lot of mileage out of brass...

Extremely rare for one to acquire a rebuild with a chamber of the same dimensions as the previous example.

It probably happened on the first firing.
In my experience nickel plated brass Is much more brittle