Given the option, should I go with 7075 instead of 6061 for the upper or is it not going to make a difference?

Who is the go-to for enlarging a standard AR upper ejection port? It’s a billet receiver if it matters.

7075 all day and everyday...  Aero Precision makes a great XL receiver

Aero and Anderson both make an enlarged port model and both are 100% good to go.  I have both.  I cannot recommend one over the other except for the lower price of the Anderson.

If you have an upper in mind that does not come with an enlarged ejection port, Paladin Machine Shop Service, tp555(at)windstream.net, will enlarge them and will also square the front of the receiver if asked and you'll have it back within two weeks and at a very low cost.  Less than $50 for sure, WAY less unless you count shipping both ways.  He has done more ejection port enlarging than just about anyone in the country and has done most of mine, until I switched to buying Andersons that come pre-enlarged.

6065 or 7075, both will work.  I also have both and I don't see a lick of difference.  Many billet are 6065, or used to be, and that is what I have on one of my .458s and it has never given me a lick of trouble.  I know it is in vogue to say 7075 no matter what these days but in my personal experience with uppers made from both, it doesn't matter a lick.  My .470 Rhino and .500 Phantom are both older DPMS LR uppers and I am pretty sure they are 6065, along with the DPMS old LR 6065 lowers, and you'd never know it unless I told you.    Those two rounds will punish the upper and lower a hell of a lot more than a 5.56 or even a .458 SOCOM.

Attached File


This fucking dude... he knows the SOCOM.  And p.s.... tromix, your welcome OP

Thanks for the info. I do already have an upper in mind so I’ll check out Paladin.

The price difference between the 6061 and 7075 is only $30 so I’ll probably just get the 7071.

I’m looking at the 14” Tromix barrel with an SLR gas block which says it needs a 1.35” ID on the hand guard. In your opinion, is going with a guard that is exactly 1.35” ID (Geissele would be my first choice) cutting it too close?

While I agree with the point made, I believe you meant 6061/7075

Dremel, files, whatever you have handy.

If you dremel/file yoursef and aren’t mindful, your dust cover may not close anymore. The detent in the dust cover needs a bit of shelf on the top of the ejection port to latch closed. Better off having someone experienced do it.

Yea I’m not too keen on doing it myself without seeing a pro job in person first.

Of all the shit I’ve wasted money on in my life another 40 or 50 bucks to have this done isn’t a huge deal.

Yes, of course.  Thanks for pointing that out.

I have done a couple of ejection ports myself and by the time you tape everything up, Dremel out the bulk and finish dressing up with a Pillar and round file, along with several checks to make sure you are not getting too much off the top (by the way, I only remove very little off the top) then clean up all the shavings that go every freaking place, it's not worth it to me anymore.  I either buy one already enlarged or send it off to Thomas at Paladin.  He does not touch up the raw aluminum so do your Duracoating or Ceracoating after the port enlarging.  Or if leaving the receiver black, scuff the cut lightly with Scotch-Brite and then hit it immediately with Birchwood Casey's Aluma-Black. Aluminum oxidizes very quickly and for best results with AB, cleaning the cut area with Alcohol then scuffing with SB and hitting with AB as fast as you can will give better and longer lasting results.  And when you put the AB on, let it sit a couple of minutes and add more if needed.  If you see it smoking a little good, you are getting good penetration, and yes, I am still talking about blackening the raw aluminum cut.

Since you're already buying a Tromix barrel (I'm assuming straight from them) why not get the upper they sell?  I did and couldn't be happier.  I don't know if it's 6061 or 7075 though.



If you don't like the engraving, they have blank ones for $130.

TROMIX uppers are run of the mill “milspec” 7075 with the enlarged ejection port and caliber engraved on the left side.  You can also get an engraved ejection port door if you like.  Other than the engraving and enlarging there is nothing special about them, but they are nice.

They also have a non-engraved upper, that I posted a link for above.