260 AI What brass?

[mo]

Going to build new F-class rifle and looking at the 260 ai. Which would be the least amount of prep time. The 308 Lapua necked or the 243 Lapua necked up?

I read the article on the Accurate Shooter about the 243 Brass leaving a donut when necked up. Will the 308 brass do the same?

What about sizing the 243 brass to 7mm, then back down to 6.5 would I still have the donut problem?

 

[Johnboy]

hey I am just stabbing in the dark here.but to me I would think necking up the 243 Lapua brass would give you a less of a problem than necking down 308 brass.necking down the 308 brass will give you alot more brass to cut down for an over all case length and then you will have to trim the necks down because of the brass in the neck area will be from the shoulder area of the 308 brass.meaning to thick for a tight chamber for a match chamber.but with the 243 brass you will only be sizeing the brass up .5mm(.021) more than the 6mm 243 bullet.which is .021 difference from the two.kind of like the same as 7/08-308.and this I have done with no problem many times.

but hey I do not match shoot.just seems more of a chance to have problems when sizeing down.did it one time when resizeing for a 22-250 with 243 brass.and I had to thick of a neck area when I went to chamber the brass empty it still would not chamber.(too thick)was told that I would have to trim the necks down to be able to allow for the neck to expand in the chamber and not cause alot of pressure while fired.(hint blow up)so I turned away from the 243 brass and just bought some 22-250 brass.

but will also say that I think alot of the rem brass.have never had the type of problems you read about the other guys have had.maybe I am just lucky or something.but really like the remington brass.always order my brass from Midway and have yet had a bad batch from them.would try winchester brass but read alot that guys have been haveing to send it back to winshester.mostly from off centered fash holes or the cases looked like they have been in a 3 year loads hands.even to add I do not weigh my brass.think its to much of a mind thing for me to do it.think the weight difference is all in the case head.so I just do not weigh my brass.but hey this is all based on my opinionso take it with a grain of salt.just thought that I would give out my .02 cents worth.hope was able to help or try to help.

 

[J E Custom]

I would recomend using the 308 Lapua brass and neck it down.

After necking it then you can turn the necks and end up with some fine brass that will last
a long time and be the best quality brass that you can have.

The 260 Rem brass is very good and if prepped and sorted (You may lose a few but at the
price so what) and all you have to do is fire form it.

If I were hunting I would go with the Rem brass. But for a match rifle I would have to use
the Lapua brass because of quality and Life.

J E CUSTOM

 

[Mikecr]

I would also go down from 308.
Leave a bit of false shoulder for fireforming..

 

[Limbic]

How do you know if you have "donut" issues are not. The donuts are inside the neck near the shoulder/neck junction arent they. I checked a bunch of my .243 brass that I expanded for reg 260rem work. I couldn't find any problems with donuts.

 

[J E Custom]

How do you know if you have "donut" issues are not. The donuts are inside the neck near the shoulder/neck junction arent they. I checked a bunch of my .243 brass that I expanded for reg 260rem work. I couldn't find any problems with donuts.

The term "Donut" refers to the small amount of fire formed neck left to center the round
after sizing.

It is not an issue just the results of a sizing method used by some.

If you full length size you should not have a "Donut" at the base of the neck.

J E CUSTOM

 

[Mikecr]

How do you know if you have "donut" issues are not.

Well, if you hit step resistance while seating a bullet deep enough..
You may have driven neck brass nearest the shoulder outward, & you'll likely have inconsistent or flat out too much tension.
It can be checked with pin gauges as well.
Now if you don't seat bullet bearing to a doughnut, it may not be of any concern really.

Cases taper in thickness from the web all the way up into necks.
And with this, doughnut's result from shoulder brass in neck real estate.
-Necking up brass, which causes a bit of shoulder to become neck.
-Lengthening the neck(for a wildcat) through forming, without following up with turning.
-Too much FL sizing. If you're forced to body size heavily, the thickening brass may roll up the body towards and eventually into the necks. This takes repeated offence.
You see this first as cases lengthening, creating the need to trim often. Then you might notice doughnuts. Then a ring of thinning in front of the webs(guess where that brass went). And finally, case head seperation.