I have some loaded with 20 gr. of Alliant 2400 powder and they work very well out of my Ruger Alaskan and SBH revolvers and my Henry .45 Colt Carbine.
Now what would be a safe load for the 25-7 using 2400 or Unique powder? From some of my old water jug tests using this bullet there was little to no expansion at 850 FPS at the Unique 8-8.5 level.

If you are referring to Hornady product 45200, As you already know that projectile is intended to be used at a higher velocity than Unique can drive it to in that casing

I am not a user of 2400 so I can not really comment on it's use with this powder

I would stick with them in the Ruger only loads or some 454 loads.

It is a shame to put an expensive projectile where it is unable to achieve peek performance

__________________
"Acta non verba"

Yep I agree. I have 200 of them and may just keep those for the Ruger and Henry loads where they really shine.
I always see Speer Gold Dot or deep curl bullets mentioned in some .45 Colt loadings but trying to find those bullets online or elsewhere even in the "good times" was a problem.

Well, Hodgdons lists this bullet in their "regular" 45 Colt data using CFE Pistol with a START of 8.0gr @ 832 and a MAX of 8.8gr @ 915...

This is interesting as there is both a range (effectively +10%) AND their START load @ 832 fps is actually "in the ballpark" with almost ALL the other (15!) listed powder's MAX loads! This should be a good thing.

The O/P doesn't really describe the intended use but somewhere in the midrange might just develop enough additionally velocity to initiate expansion...?

Cheers!

P.S. I have a supply of the aforementioned Speer Deep Curl bullets and this looks like a good place to start.

The Hornady 240 gr XTP MAG bullet requires more velocity to open. The 250 XTP mentioned by the OP not as much. It is pretty well recognized that M25 Smiths can be loaded to 23k psi as that is pressure of a 45 acp +p load and the cylinders are the same size.

I have fired many 250 XTP’s in my -5 and -7 M25’s. My load is 18.5 gr 2400. Safe in MY guns. Work up carefully.

Dan

Hornady lists the suggested velocity range for their 250gr XTP at 800-1600fps.

In your related thread here 20.0gr/2400 with the 250gr XTP from a 2.5" bbl Ruger Alaskan got 1100fps & showed pretty good expansion.
Some of my Hornady XTP bullet test results...

John Linebaugh suggests 20.0gr/2400 with 260gr L-SWC as "Recommended Max" & 24.0gr as "Absolute Max" in the S&W M25 45 Colts.

In Starline brass I've loaded the HDY 250gr XTP with 19.0gr/2400, COAL@ 1.600", with no issues in my M25-13.
QuickLoad estimates that's 1126/me & 704/me (5" bbl) at 22.4K psi

Q-L estimates 19.5gr/2400 is 1157/mv, 744/me @ 23.8K psi.

Q-L estimates 20.0gr/2400 is 1189/mv, 784/me @ 25.4K psi.

.

Q-L estimates 9.5gr/UNIQ is 1005/mv, 561/me @ 19.4K psi.

Q-L estimates 10.0gr/UNIQ is 1044/mv, 605/me @ 21.3K psi.

Q-L estimates 10.5gr/UNIQ is 1081/mv, 649/me @ 23.3K psi.

.

These pressures are not the optimal for 2400 but it's a very forgiving powder & doesn't mind being loaded on the light side, unlike H110/W296.

As mentioned, the 45ACP M25s can shoot 45ACP +P loads with a SAAMI max of 23K psi & many of us shoot 45 Super in them with no issues.

.



.

__________________
Waiting for the break of day