Mag or mag block issue?

[Caduceus]

Hi all
Just installed a Hahn block on an SBR and topped it with a PSA 7.5" upper. Using 2 different ASC mags, 115 and 124gr ball worked fine, but 147 HST wouldn't feed. The bolt hold open was also inconsistent.

Using a PSA glock lower, the upper fed all the above, including the 147s.

I've read good things about Hahn blocks, so I'm wondering if this is most likely a magazine, block or ammo?

Any thoughts?

[bfoosh006]

Deleted

[Caduceus]

Will try. I just got 2 metalform in yesterday. I also read somewhere recently that Colt styles hiccup more with HP rounds.

[wanderson]

FWIW when I put my first 9mm Colt pattern AR I used a Hahn toploader block & Metalform mags cause that seemed to be the overwhelmingly most popular trouble free setup.
No issues in 4 years of use, mainly FMJ round nose and some truncated (flat nose) bullets.

I've never owned any ASC mags, but in another thread someone claimed the Metalforms feed flat/horizontally and like to sit high while the ASCs feed at a slightly more upwards angle and like to sit low. So a bottom loading mag block can be adjusted to work with both but Hahn top loaders prefer the Metalforms.