Lower for my 450

[Stealthshooter]

I love my RRA lower receiver but I'm think I'm going to get a separate lower for my 450 eventually. I think I have found the winner!! Not only does it look like a work of art but I like supporting businesses in my state!!

http://seekinsprecision.com/index.php?o ... &Itemid=14

[BillytheKid]

Very Cool!

[Hoot]

Very Futuristic Looking indeed!

Being in Minnesota, I like the glove friendly trigger guard. I also love my RRA lower with 2-stage trigger. 2 lbs takeup, 2 pounds break. However, it seems that nearly 1k or 450b rounds and about 500 .300 WSSM rounds may be taking their toll on the front pivot hinge, pin, or both. It has been getting sloppier over time, more than I'd like. The rattle can be eliminated with a small piece of silicone rubber jammed under the takedown pin tang like an accu-wedge, but that's bandaiding the problem, not solving it. I am reluctant to use one of those adjustable diameter pivot pins, or the old trick of an o-ring around the pivot hinge, though also helpful, as they are yet another bandaid. It's not the upper as my three other uppers, which share that lower, started out fitting beautifully snug in that same lower and all of them are equally loose now in it. The 6.5 Grendel and 5.56 are not nearly as punishing a caliber as the thumper and thumpette.

Not to hijack the thread, but who makes the generally accepted strongest material lower out there aside from a steel one, which I've already seen? I could care less about what is engraved on them. Brute strength in the pivot hinge is the order of the day. Given aluminum is not as strong as steel, I have not tried a new pivot pin. Should I?

Hoot

[Stealthshooter]

Have you thought about trying one of these to take the slop out? http://www.demontactical.com/demon-tact ... -pins.html

Here is a list of top end lowers. http://www.ar15.com/forums/t_3_4/477813_.html

[commander faschisto]

I vaguely recall reading about something called an Armalite National Match oversize pivot pin somewhere out there in the ether...might be worth some quality time with a search engine?

[Hoot]

Have you thought about trying one of these to take the slop out? http://www.demontactical.com/demon-tact ... -pins.html

Here is a list of top end lowers. http://www.ar15.com/forums/t_3_4/477813_.html

When I saw that one with the stainless steel hole inserts I got my hopes up until I read closely and realized it was just the trigger and hammer pin holes. Why not the pivot and takedown holes? It did however give me an idea for machining and putting my own stainless steel bushings in. Hmmm...

Point of clarification: the rear takedown pin hole is not the problem. The front pivot hole is the problem. It allows the uppers to wobble both side to side as well as up and down. I'll do some more precise measuring. Hole slop begets more hole slop as the mating halves batter one another with a running start, albeit a small running start. there's always 1 mil nickel or chrome shim sheet that you can cut to line a hole with. I had some, but darned if I can find it now.

Thanks for the tips. My rule of thumb is that if a manufacturer puts a lot of effort into eye candy crap like flags, skull and crossbones, molon labe logos, whatever decorations they choose to lure in the mall ninjas, that's time and money they could be putting into making the design stronger. Just my personal opinion. Fancy window dressings don't do anything for performance. They exist to draw in the people who value form over function. Maybe that blued steel one is the best choice after all.

I realize many would argue that slop in all four planes is not a problem, but it still worries me, especially with these heavy hitters. Thanks to everyone for their suggestions. If it gets to bothering me enough, I'll do something about it as opposed to just grousing.

Hoot

[Texas Sheepdawg]

I did quite a bit of research on Lowers earlier this year and Stag Arms got my business.
I bought two standard 5.56 lowers with consecutive serial #s. They are "Mates". The machine work is very good and it was a total blast putting them together, (except for the Bushmaster parts on backorder fiasco). I should have bought the RRA parts kits or the Stag parts kits, but I really wanted to give Bushmaster a chance to come through. But that's another story. I ordered the lowers direct from Stag and then called my FFL guy with the order details and we both had very good service from the folks at Stag Arms. And for $135.00 per lower, it was a great deal.
http://www.stagarms.com/index.php?cPath=18_30

[commander faschisto]

Steel bushings are a good idea, and no real problem for the rear takedown pin, but the front pivot pin hole has the design problem of the flat surface on the rear side of the hole. That would make for an interesting machining effort!

[Hoot]

Steel bushings are a good idea, and no real problem for the rear takedown pin, but the front pivot pin hole has the design problem of the flat surface on the rear side of the hole. That would make for an interesting machining effort!

Ooh, I forgot about that detent also. Good point Mike. the complexity just went up a few notches.

Hoot

[Siringo]

Hoot -- you could always go the JB Weld route. Machine (via a dremel tool) a small groove around the base of the upper near the front pivot pin and bed the upper to the lower. The would eliminate the rocking side to side movement.

I cut up foam ear plugs and wedge it in between the upper pivot boss and lower frame outer face.