View Full Version : A lower is not a lower: rifle buffer tube not fitting Mega

10-30-2009, 9:44 PM
I tried to finish my RRA Varmint A2 24" earlier. I waited for this back order about 5-6 months. The rifle length buffer tube was not fitting my Mega lower (purchased Nov 2006). After 1-1.5 twist, it's hella tight. I pulled one of my unbuilt Lauer lowers (LMT cut, purchased Dec 2008) and it screws on very easily. As additional test, I pulled the buffer from my U15 stock build (Doublestar OLL, purchased Nov 2006). It screws into the Mega easily too. I thought the issue might be both the buffer and lower because the tube would not go into my new PRS stock. (I found out later I had to loosen the 2 screws on the PRS, though it still didn't quite slide in very easily. It was concluded later in the day buffer was not the issue.)

I went to a local gun store and checked their rifle length buffer tubes. Theirs was able to screw in more, but still very tight before it can get into the buffer retainer (and he pointed the 2 screws to be loosened on the PRS stock. Thanks!). I wasn't sure if I wanted to force the issue with a little grease to help. Or just uninstall all the LPK and put it on the Lauer. I didn't have the right size punch to push the roll pins out though (1 punch too small and other I use to push in is just slightly larger than all the pins).

I had a N4 lower coming to complete my Noveske SPR VIS upper (to "noveske" it out. :rolleyes:). I decided instead to pull the attached built Lauer lower off it, remove the UBR and just swap it out for the Varmint A2 24" upper. Everything now fits fine. Odd that the Mega will not take the rifle buffer but on my other Mega build (carbine, CMMG upper on a CTR stock), there was zero issues.

Here are some pics. I guess an lower is definitely not a lower even among better brands.

Mega having problems with buffer tube

Lauer w/o issues

Full build

* Rock Rivers Varmint A2 24" upper (bead blasted bull barrel with Badger tactical latch)
* Lauer lower (LMT cut)
* Magpul PRS
* Hogue grip
* bullet button (of course)
* Larue LT-104 mount on a Super Sniper 20x (now shared with my 20" build)
* shooter's ridge bipod (shared also with my 20" build)
* Midwest Industries Flip-up gas block front iron sight and low profile rear sight. (also shared).

Maybe when all the projects are over (yah right), I'll get dedicated glass and BUIS on this build.

10-30-2009, 9:49 PM
Lowers are lowers. It is unreasonable to expect every single lower to be built exactly right. You just happend to get one when the buffer tube wasn't cut right. Contact Mega and they will replace it. http://megamachineshop.com/

10-30-2009, 9:56 PM
I have two Mega lowers from about the same time frame.
They both have rifle length receiver extensions on them, on PRS one A2.
I didn't have a problem with either.
Who made the receiver extension?

The threads can vary on both the receiver extensions and lowers a little.
If the tolerances stack up you may run into what you did.
I have one lower that I could fit a Vltor mil spec carbine extension on but not a Stag mil spec.
That lower also fit a RRA commercial extension but not a CAA commercial.

Nice build :)

10-30-2009, 9:58 PM
true. maybe i should reword the title to not all lowers quite cut perfectly. i have a piston upper coming soon to put on a sopmod (maybe). if a milspec carbine tube fits perfect, i'll keep it. would like not to have to punch anything out. and since my other mega fit my ctr/carbine buffer jsut fine, i'm expecting it to be fine. just sharing. found it kinda strange.

Desert AIP, i don't know who cut the receiver tube actually. I don't think those are usually listed in most online sights, right? I saw the threads vary because the gun stores tube screws in a little futher, but still not quite there yet before it gets very tight. so i guess it's how the Mega is thread. I'll still keep it. I guess it'll be the piston upper on this one and a collapsible stock. hopefully coming soon.

10-30-2009, 9:58 PM
That can happen, and has happened, with every brand of lower.