When I was there picking up my lh 77 there was a customer picking up a rh stainless 77 in 450 (Randy said they got "a couple" with the lh shipment) and it had the threaded/belled muzzle.
I also have one of the threaded 16.5" Americans which started me down the path to get a suppressor. With the addition of my new (unthreaded) 77 .450 I'm rethinking the suppressed .450 idea but I've read that you can use 5/8"-32 for the .450BM. Might work better on the thinner/unbelled 77 barrel?
from
Silencer Central website:
Common Pitch Range.17 to below .243 – 1/2×28
.243 to .300 Win Mag – 5/8×24
Common Platforms.223/5.56 (AR15) – 1/2×28
.30 Cal (AR10 etc.) – 5/8/24
300 BLK – 5/8×24
AK – M 14×1 LH
*350 Legend – 1/2×28
**450 Bushmaster – 5/8×32
458 SOCOM – 5/8×24
