Basically I forced the pins in with a mallet, not realizing there was a detent. Stupid, I know, but to be fair I had dropped the gun off to have the barrel shortened and never had to push the pins out myself. When I got it back it was separated into upper and lower receivers.

The pins seem to work fine still with just an extremely small amount of finish/ material gone from the holes in the receiver. However, I can now push the front pin out without using the tool if I apply sufficient force (about the same as required on a standard AR td pin). It all seems tight and secure to me but I’m wondering if the front pin is at risk of walking out during fire. I’d just test it myself but currently don’t have access to a range area.

Those pins were made to utilize the tool to take down and assemble.  If I were you, I get a set of milspec pins to install and forget about having to use a tool in order to take down or install upper/lower.

Or get a new set of HK pins……