AR-15 mag catch problem

[Pipedoc]

So I built 2 AR's with Anderson lowers. Don't remember the brand of LPK's. Now I have built several others with no issues and now I have not 1 but 2 that it is hard to get the mags to seat properly. I've tried several mags with the same results. the mags do seat if you rap them hard into place. Once the mag is seated both rifles run great. I am looking for someone who can rectify the problem on both. I have tried adjusting them with no positive results. Any help would be appreciated and I am willing to pay to get this problem resolved. thx Doc

 

[Toy00taco]

If you have any other lowers that are currently functioning correctly I would remove the magazine catch, spring and release from one and try it in the lower that is not functioning. This way you can narrow down if it’s an issue with the unknown LPK or the Anderson lower receiver.