Subsonic Cast Loads for a 7MM Rem Mag

[Milanodan]

I just loaded a few old 7MM 152 gr. boolits that I cast and lubed about 40 years ago. Trying to keep the velocity down, I used 10 gr. of some old Hi-Skor 700X (also ~40 years old, but it looks and smells fine). My old Lyman book shows 13.5 gr. as a 32ksi starting load, but the speed is way above Mach 1.

That got me thinking about how low I could go to get a subsonic load--w/o sticking a boolit in the barrel. Any ideas?

[rugerman1]

http://data.hodgdon.com/cartridge_load.asp shows a trail boss load with a 140gr j-word @1400/21k psi.I never used trail boss in a 7mm rem mag,so I can't offer any advice past what is listed there.

[MNruss]

The expansion ratio is really working against you here.
Subsonic w/o being position sensitive is gonna take some trying.
Of course, that's part of the fun! :-)
Russ

[Milanodan]

Guess the 26" barrel doesn't help either, and my old Pact chrono doesn't work well either.

Guess I'll ease back on the powder until the "crack" is gone. Must check bore after every no-crack shot.

[Milanodan]

Fired a couple of rounds, 8 gr. 700X with 152 gr. Boolits. Chrono said 1250 fps. I'll load some with 6 and 7 gr. and see what happens.

[seppos]

Dacron filler is the key in this one.
I have loaded subsonic loads with cast bullets to .338 LM and j-words to .243 Win.
Remember to start from the bigger loads and go down to the smaller ones..;)
Experience has shown to me that one needs to work less in pulling out the stuck bullets from the barrel that way..;)

S