Quote Originally Posted by USN-PO2 View Post
I have 16" uppers in both 350 Legend and 450 Bushmaster. Vortex 3-9x44 scopes on both.

The magazines can be problematic, depending on the ones used. I needed to modify the front of the magazine so the bullet wouldn't catch on them as their sliding forward. It's relatively easy to do with a Dremel. Most AR magazines are flat across and it needs more of a U shape to clear. Doesn't need much. Go slow and test often.
You can buy magazines for both calibers that are already "fixed".

Both are fun to shoot. I shoot the 350 Legend more since the local Walmart usually has ammo cheaper. 450 Bushmaster is harder to find and fairly expensive.
Just curious, does your 350 Legend barrel have a single center feed ramp, like the Bushmaster, or dual feed ramps like most other AR barrels? They are a dual feed magazine of course, but I've noticed some companies making the barrels with a single feed ramp and have to wonder if some of the mag issues stem from that.

I haven't seen any need to modify my C-Products Legend mags, but my barrel is set up for dual feed as it should be. What is important though is using a magazine without the internal ribs that a 5.56 mag has; either actual Legend magazines or 5.56 mags can be modified. Lancer 300 Blk mags might work too, but I haven't tried mine in the Legend. Probably should do that.