noob: ar 15 80% lower question

[n3rdc0re]

So i picked up a springfeild xd 9mm about a month ago and now im looking to do my ar 15 project. I was wondering if i could build a multi cal lower from an 80% one?

[Riceball]

I'd say, yes, within the limits of what a standard .223/5.56 AR lower can normally handle. So that means the usual .223.5.56 and .22LR but not .308 or anything else in the .30 caliber range.

[n3rdc0re]

A buddy of mine told my brother inlaw (has a pair of m16s) that he would able to fire the 6.8mm and 300 blackout rounds with the proper uppers.... this true?

[hardlyworking]

Yup.

6.8 requires new magazines from what I gather, 300BLK uses standard mags.

[yari]

You can build it into whatever you want. A pistol, rifle, any cal. If you don't engrave it saying this is a .223 rifle how can anyone prove you didn't build it as a 9mm pistol?

[n3rdc0re]

Nice what about the 6.5 grendel, will i need diffent mags too?

[tpuig]

Take a look at the different uppers available (theoretically) from a place like Midway. There will be a lot of different caliber options. Most will use a magazine specific to that caliber.

So if you already have an AR-15 lower, there are a lot of options to put on it. Just depends on your budget.

[stix213]

Lots of options available. Mine for example is a .50 Beowulf pistol build. Go crazy big with it, go pistol rounds, swap back and forth uppers as long as the caliber doesn't require specific parts in the lower. Have fun.

[NiccoHel]

Hopping onto this thread instead of posting a nearly identical one...

I've seen a few places offering 80% lowers for a pretty good price, and I am somewhat competent with the machining required to build them. So, if I picked one up, are there any CA-specific requirements regarding finishing an 80% AR lower? For instance, do I have to fit a bullet button, or is that only if/when the rifle is assembled and includes the "features"? I'm fine with a fixed stock, but I definitely want a standard pistol grip.

[n3rdc0re]

Thanks for the info guys

[paratroop]

Hopping onto this thread instead of posting a nearly identical one...

I've seen a few places offering 80% lowers for a pretty good price, and I am somewhat competent with the machining required to build them. So, if I picked one up, are there any CA-specific requirements regarding finishing an 80% AR lower? For instance, do I have to fit a bullet button, or is that only if/when the rifle is assembled and includes the "features"? I'm fine with a fixed stock, but I definitely want a standard pistol grip.

Pistol grip is an evil feature for centerfire. You would need a mag lock if you don't want to go rimfire.

[Oceanbob]

Is there a reason you don''t just buy a stripped lower for $150 bucks and assemble it from the ground up?

Seems a lot of work machining an 80% and the added expense of time and anodizing..etc...

You can simply buy multi caliber and do what you want..

[goober]

Is there a reason you don''t just buy a stripped lower for $150 bucks and assemble it from the ground up?

Seems a lot of work machining an 80% and the added expense of time and anodizing..etc...

You can simply buy multi caliber and do what you want..

unless you want to build a pistol, or have the satisfaction of having built it yourself, or don't wish to have records associated with it, or want to do something custom, or....
cheaper? no.
easier? no.
better? depends on your criteria.

[Riceball]

Is there a reason you don''t just buy a stripped lower for $150 bucks and assemble it from the ground up?

Seems a lot of work machining an 80% and the added expense of time and anodizing..etc...

You can simply buy multi caliber and do what you want..

I could be mistaken here but from what I've gathered from reading here on Calguns the biggest benefit of building an AR using an 80% lower is that it has no serial number and requires no DROS and thus, technically, doesn't exist. However, I don't know if that would make it immune from any future registration requirement or if they would still be legal to buy if there were an AW ban in place.

[Riceball]

Another option that will work off of any regular AR lower is the AR57 upper. This upper just goes on top of your lower and allows you to fire the FN 5.7mm round that the P90 and the FN Five SeveN use, it does require different mags but they go on your upper like on the P90 and your mag well becomes an ejection port. I don't know how expensive 5.7mm rounds are or how available but getting the AR57 upper would get a pretty unique looking AR.

http://www.57center.com/6m8/ar57-upper-assembly.html