Need Help! What is a 250 HP ?

I bought a box of loaded rounds with SP bullets and a headstamp of "250 HP - REM" .
OK, I trust that Remington made the brass/original loading. I will pull the bullets as I cannot determine age. The rounds are pretty shiny, no corrosion or pits, etc, no tarnishing.
What have I got? Ballistics? pressures?

250 grain hollow point bullet. Probably a reload as the standard load is a 240 grain bullet. Pull 'em, re-prime, and reload. great hog load.

I think I found it. 250-3000 Rem -UMC cases made prior to Remington-Peters taking over. o "22 Savage HP".

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The heaviest .22 cal (.224") bullet is about 75gr.
The heaviest .25 cal (.257") bullet is about 120gr.

A 250gr bullet would be suitable for a .35 cal (.358") chambered rifle.

The .250-3000/.250 Savage, normally loaded with a .257" bullet (with a max weight of 120gr), is different than the .22 High Power, which uses a .228" bullet.

The .22-250 uses a "normal" .224" bullet.

I've been playing with & repairing guns since the early 1960's, and have never come across brass headstamped "250HP-REM".

I do know that (for a price) some of the smaller brass makers (like Starline, Bell & others) will make up a batch of brass headstamped however the customer wants.

If you have a ".25 HP", I would WAG that somebody had a .22HP that they had rebored to .257" so they could load bullets easier to find than .228" bullets.

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250HP= 250 High Power= .250 Savage /.250-3000

correct. these cases are 250-3000 savage, made prior to Remington changing to Remington-Peters.
These cases then were apparently manufactured prior to 1946, when Remington officially closed the Union Metallic Cartridge Co. operations in Ohio and San Paulo Brazil, and started using the "R-P" headstamps on everything subsequently manufactured.
--Shotshell headstamps not included - they are a mystery in themselves.

No gun in question, just the case headstamp query. I'm much too impatient to be a historian...