Just fireformed some 250 Savage brass (for my new-to-me 250 Sav A.I.). Trying to determine what the max case length is. Tried googling it and only came up with 1.912, same as standard 250 Savage.

Is that correct? If so I'd assume 1.892 would be the 'trim to' length.

sounds good to me

https://loaddata.com/Cartridge...Ackley-Improved/3099

Sierra #5 says case length is 1.912 and trim to length is 1.900.

Steve.........

Ackley improved chambers should be as long as the parent cartridge because the beauty of this arrangement is the ability to fire factory ammunition. Trim-to length is apparently an arbitrary number shorter than the case mouth touching the end of the chamber. I was under the impression that the rule of thumb was .010" less than max. except for some pistol cartridges. For 250 Savage this would be 1.902", but a touch more or less is unimportant. When Ackley cases are blown out they get significantly shorter (.020-.040"+) than the parent case & it takes quite a number of firings to reach even trim-to length. I usually trim mine after fireforming & resizing just enough to square the case mouths. It often takes about 8 to 10 full house firing cycles before it's necessary to trim again.

Since a picture is worth 1000 words there are some pictures showing the relationship between chamber & cartridge case here...

https://forum.nosler.com/viewtopic.php?f=4&t=41029

Cases become shorter when yo fire form them.

There is no problem in this, just trim them to the same length.

Thanks Saeed and 358, that is what I experienced (they came out shorter).

While we are on the topic, does anybody know if the 'load book' for 250 Savage include data for the 250 AI? My single load book for the 257 Roberts does.

Plus 1, you do shorten a case when fireforming the 250 and most cases/calibers for that matter..In the 250 it makes little difference for a while maybe 3 max firing in my cases and never with mild loads it seems. Basically use the same as mentioned above for the standard 250-3000 length....Love the caliber, its so easy to load and problem free and a good killer of game beyond its approved scope within 300 yards at least is my experience anyway.