Fire forming 250 Sav AI

[grizlywinkleman]

Hello,

New to fire forming. My plan is to load RP 250 Savage brass with 20 gr of 3031 and some old 100 gr Sierra Spitzers that I have plenty of. The Sierra manual starts at a 38 gr charge of 3031.

Will 20 gr be sufficient? Is there a good resource where I can find safe minimums that wont lodge the bullet in the barrel or not fully form the brass? Or am I over thinking it?

Thanks in advance for your help!

Ryan

 

[MagnumManiac]

If the AI chamber is cut correctly with negative headspace of .003"-.005", then you should be good to go using a NORMAL load to form brass. If 3031 is all you have, use a middle load, not a start load.
If not, then a forming load using a fast pistol powder, COW (Cream Of Wheat) and a snug piece of of TP is in order with a false shoulder to keep the case head against the bolt.
I use Clays to form all of my improved cases, including my 375 Weatherby and 338-416 Rigby Improved.
My 22-250AI only needs 10gr to form a case, the next full powder load gets all corners nice and sharp.

Cheers.

 

[just_jon]

i was told by an old timer smith back before I became an old timer to use green dot shot shell powder. His rule of thumb was to use 1/3 of a normal powder charge. I use 15.3 grains in my 250AI with the heaviest bullet I have seating touching the lands.

 

[kiwikid]

Before I started fire forming the 250 Sav AI for my Wife's Cooper I contacted Sierra Bullets to see what their recommendation was since they use this cartridge for their 25 Cal bullet testing.

One of their Techs emailed me saying to use 35.3 grains of IMR 4064 with a 100 grain bullet seated into the rifling. That load is the Max load for the 100 grain bullets in the Standard 250 Savage. I used new Winchester brass, Fed 210 Match primers and Sierra 100 grain Pro Hunter (#1620) bullets.

Fire forming the cases produced <.5 MOA 5 shot groups at 100m and the cases came out with nice sharp corners.

Once I had fire formed the cases I swapped to 40 grains of Reloader No 15 with Fed 210 M primers and 100 grain Sierra Game King (#1625) bullets at an average velocity of 3088 fps.

Here is a photo of the loaded fire formed round and a Winchester Silver Tip factory round.

 

[grizlywinkleman]

Thanks for the help. I think I'll wait on the TP trick for the next round of forming. I'm using 3031 because I don't currently use it in any of my loads. Sounds like I was going to way undercharge my loads! Ill go ahead and load middle of the road to what the Sierra manual says.

Thanks for your help everyone!

 

[Hondo64d]

Hello,

New to fire forming. My plan is to load RP 250 Savage brass with 20 gr of 3031 and some old 100 gr Sierra Spitzers that I have plenty of. The Sierra manual starts at a 38 gr charge of 3031.

Will 20 gr be sufficient? Is there a good resource where I can find safe minimums that wont lodge the bullet in the barrel or not fully form the brass? Or am I over thinking it?

Thanks in advance for your help!

Ryan

Not sure how much .250 Savage brass you have, but if you can source some 6.5 Creedmoor brass, I'm pretty sure you could neck it down and form a false shoulder and load it and shoot it.

John

 

[sierracharlie338]

One of their Techs emailed me saying to use 35.3 grains of IMR 4064 with a 100 grain bullet seated into the rifling. That load is the Max load for the 100 grain bullets in the Standard 250 Savage. I used new Winchester brass, Fed 210 Match primers and Sierra 100 grain Pro Hunter (#1620) bullets.

Fire forming the cases produced <.5 MOA 5 shot groups at 100m and the cases came out with nice sharp corners.

This more or less is how I did my 257 AI. Went with two grains under max load of standard cartridge but seated them .020 off the lands. Had to run them through twice to get proper shoulder though so the bullet being in the lands is the way to go.

 

[Seabeeken]

I form for a number of AI rounds including 250. Use a max 250 Savage load of a fast powder to get them fully formed. PO Ackley also recommended a full load.
I also use the COW method but with coffee to form with 15 gr of IMR Red,
I found the COW liked to burn and pack up in the shoulder of the cases. Coffee didn't present this issue and was also already burnt to a degree and was easier to clean from the barrel. it smells better when firing too.

 

[lancetkenyon]

I had a .250AI for years. Great round.
For fire forming, I always used 1gr below max for the parent case and 100 SMKs. Gave me sharp shoulders without pressure. Nice, moderate loads that were very accurate.
So with IMR3031, Hodgdon/IMR book shows 33.0gr max w. 100gr. So, 32gr would be my load. But, wouldn't hurt to load 31.0 to 33.0gr in .5gr increments, and shoot for groups. Nice to have the most accurate fire forming loads to double as varmint loads.

For final loads, I liked H414. Worked great, and gave good speeds. 3100 w. 100 SMKs in a 23" 1:10", or 3020fps w. 115 HVLDs.