So I'm finishing up my 9mm ar build.  I got my cmmg bolt in and I install it into my upper. Everything is good so far.  Then I try to put on to my spikes 9mm lower and the pins will not go in.  So after messing around with it for a while I decide to put a light layer of grease on the top of the feed ramps and the middle to see where it is hitting.  After doing this I see that the grease on the top of the feed ramps is making contact with the bolt.  My question is it OK to file down the two posts of the feed ramps to give it extra clearance?

Look again. This problem is usually the CMMG bolt not clearing the top of the ejector arm when the bolt is forward. Never heard of an issue when using other manufacturer's 9mm bolts. Fix is to slowly shave off some of the upper rear radius of the ejector arm until you achieve clearance.

Ok thanks will take another look

So I took off the ejector to see if that was the problem.  The upper and lower would still not go together.  So I put it back and removed the feed ramps and it went together.  So I will be removing some material off the feed ramps.

ASC magazines?  If so, you may need to remove some material from the feed ramps to get the bolt to close.  There's a lot of discussion on this forum about doing that.