Hey all,

I am trying to get Discreet Ballistics Selous rounds to feed in my rifle.

Q barrel assembly
Aero upper
Toolcraft BCG
Lancer 300blk Mags
Aero and Anderson lower


The rounds seem to be getting caught where the upper feed ramps meet the barrel feed ramps. It looks like there is just the slightest bit of misalignment/offset on the right ramp (the only one exhibiting the problem) causing the problem. I don't experience the problem when i push the magazine up. Visually it doesn't appear so much to be a misalignment so much as the upper feed ramps being deeper than the barrel feed ramps.

I polished the feed ramps hoping that would fix the issue, but it didn't.  At this point, I am wondering what my options are to fix this problem. The only thing I can think of is dremelling the barrel feed ramp a bit to reduce the offset or trying a new upper. With parts being scarce and expensive, i'm trying to avoid a new upper (especially since it isn't guaranteed to fix the issue), but i'm also pretty hesitant to take a dremel to my barrel and cause even more problems.


Any other suggestions?

Try some 20 rounders or a Magpul 300BLK mag? I’m guessing it’s mag related.

I've tried 20 rounder, 30 rounds, and USGI mag. I'm thinking its the upper/barrel because even if the mags are sitting a little low, the round should be able to feed if it first connects with the upper feed ramp - right?

i'll try to get some good pictures tonight / tomorrow.

Mag catch is good, using 300blk magazines.

I’ll get the Honey Badger out tomorrow with some Discreet Ballistics Selous rounds and see if I can replicate anything of value.

For those curious - i was able to confirm that the bullet was getting snagged on the gap / step / overhang between the upper and the lower. I coated the tip of the rounds with a paint pen and observed where the paint transferred to the feed ramps.

I'm thinking of trying another upper (if i can get ahold of another aero slick-side upper) since i accidentally took off some of the anodize when i was polishing the feed ramps. Otherwise i think i'm going to send it to Trajectory Arms to recut the feed ramps a but to match the upper.

Thanks for the suggestions / input!

I ended up trying another Aero upper. I couldn't get it to work - the round snagged on the other feed ramp, not the junction. I've already polished the ramps pretty well, so I think I'm going to give up on the DB rounds and try to trade for a more traditional HP - maybe the Hornady Subx?