Ok now comes the fun part.... As I said before AR10/LR308's I like AR15's ...have no mil spec meaning alot of stuff is not interchangeable heck even if the upper and lower should fit if ones comes from company a and the other from company b parts might have SLIGHT differences in this or that where they won't fit . That's why most people say to just get everything from eh same company..... I'm not right int he head so I decided to get a BCA upper and PSA10 lower because most of the time they fit no issue apparently....but sometimes they do need a lil fitment the requires a Dremel tool. Now...the up side to this is if you don't right and take you time you can end up with a rock solid upper and lower fit . usually they will rattle and jingle a little bit since you fitting them together well you can make them fit really tight.
Now I was of course one of the goobers who has a deal that don't quite fit as you can see
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262023-img_20250629_140708565.jpg)
Those pin holes are off just enough so I can't get my pin in so.... Dremel time !
First mask it off a little
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262024-img_20250629_141129247.jpg)
And now what part to grind ? From all the reading and watching apparently this radius right here is what causes alllll the issue so we're gonna work nice and easy with a sanding drum on both sides checking frequently
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262026-screenshot_20250629_183423.png)
And as you see I also tried some other spots just because
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262029-img_20250629_165651093.jpg)
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262031-img_20250629_165701921_burst002.jpg)
Though that part I circled was really the only one I kept needing to hit. Found. Out of you put a light behind it you could see pretty easy where you making contact and needed to grind
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262032-img_20250629_165602064.jpg)
And after about 10-15 min of sanding and fitting got a nice solid fit and this is my outcome
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262033-img_20250629_165718473.jpg)
Also sanding down just a little bit of the read take down pins head because it was hitting the top of this lil ridge but wasn't needed
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/06/full-34110-262035-img_20250629_165733816.jpg)