Hiya
I've always used Winchester brass in this 7x57AI of mine, but Winchester brass in 7mm Mauser is getting tough to find.

Would I run into any problems with using Winchester 257 Roberts+P brass? The only concern I have is maybe necks a little thin..

Thanks

My data shows the Roberts case is 2.233 the 7x57 is 2.244 when you neck it up it will get shorter yet. You would also need to work up your load again because I doubt the capacity is the same.

I've take 280 brass to 375 & 416 so I would not worry about taking 257 to 284.

the +p brass does what you want but it does have a bit less capacity.
most of the +p brass has been a bit long from the bag, and was trimmed to 2.225 easily enough i think i had 5-6 out of the 300 i bought to make regular 7 mauser brass from that was under that length.
my best ackley loads have been with remington brass.
the +p brass didn't get too thin, it did however have thickness differences in spots,and some of it had excessive run-out [up to.0020] untill fired in the chamber.

Ok.. I guess I can start using Rem brass, I do have some and they are fine as far as I can tell.
Thanks.

I was also wondering.. If anyone has used any of that Privi brass?

I was working the Cartridge Collectors booth at the NRA show in so.cal a bunch of years ago and the 257 R +P has just came out and I asked the people at the Win booth what the difference between the regular and the +P brass was and they said that the +p brass was marked +P and the non-+p brass was not. I fired a box of +P in my 257R and with the same case lenght and checking capasity with a fine ball powder(H110?) with my regular case they were both within a 1/2 gr of the same capasity. Things could have changed over the years. I uses Privi brass in my 9.3x62 and in 5 different military cartridges and have had no problems with it.

You can use 6mm Remington or 8mm Mauser...or ANY x57 brass. If worst came to worst you could use ANY .473" case head that is long enough...just resize and trim.

Keep watch at Midway, Midsouth, Cabelas, Graf and Sons or Natchez. Norma or RWS is usually always available through someone...100 cases should last a life time of normal hunting. If you are varminting with it, buy a couple hundred extra. Several ways to skin that 'Cat.

Luck

I neck up .257R +P brass for my 7x57 without problem. I use a tapered expander ball in my F/L die then neck size only. The case headspaces on the neck/shoulder junction just fine and if that is where your AI headspaces you will be fine.

Yes they are shorter but not enough to make any difference except to save trimming.

I buy that brass as it is cheaper than other brands of 7x57 brass when it is available here.

I just got 100 Win 7x57 cases from Graff, think they still show it in stock.
C.G.B.

midway has all the 7x57 you need
http://www.midwayusa.com/brows...*652***670***9013***

if you are worried about pressure, start with 270 brass