Stupid question that I should know the answer to RE AR lowers and caliber....

[gungate]

Stupid question that I should know the answer to and probably could be found if I wasn't too lazy to search.......

If I buy a .308 upper will it work with my Milspec AR-15 lower?

Like this one:

Aero Precision M5 20in .308 Winchester RM15 Complete Upper Receiver Up to 10% Off w/ Free S&H — 4 models

Shop Aero Precision M5 20in .308 Winchester RM15 Complete Upper Receiver | Up to 10% Off 4.2 Star Rating on 6 Reviews for Aero Precision M5 20in .308 Winchester RM15 Complete Upper Receiver...

www.opticsplanet.com

 

[trickg]

Stupid question that I should know the answer to and probably could be found if I wasn't too lazy to search.......

If I buy a .308 upper will it work with my Milspec AR-15 lower?

Like this one:

Aero Precision M5 20in .308 Winchester RM15 Complete Upper Receiver Up to 10% Off w/ Free S&H — 4 models

Shop Aero Precision M5 20in .308 Winchester RM15 Complete Upper Receiver | Up to 10% Off 4.2 Star Rating on 6 Reviews for Aero Precision M5 20in .308 Winchester RM15 Complete Upper Receiver...

www.opticsplanet.com

No. They are considerably different. You need an AR10 lower for an AR10 upper.

 

[DutchV]

You want one like this for that upper.

M5 (.308) Complete Lower Receiver, Standard - Anodized Black

Shop M5 (.308) Complete Lower Receiver, Standard - Anodized Black and more online at aeroprecisionusa.com. Free shipping on all orders over $99.

www.aeroprecisionusa.com

 

[rseymorejr]

No. And the AR10 uppers and lowers need to match, they aren't all compatible like AR's are.
I found this out the hard way

 

[fabsroman]

Yep, there are two different styles of AR-10 lowers/uppers. I answered this a long time ago regarding the differences, but I cannot remember what thread that was in.

The original Armalite AR-10 lower/upper is different than the LR-308 type lower.

Here is a good write up:

DPMS vs Armalite: AR 10 & LR 308 Pattern Differences

Do you know the difference between the DPMS Gen 1 LR 308 and Armalite AR 10 platform patterns? Before creating your next AR build, read our complete guide!

www.80percentarms.com

All of mine are LR-308 lowers.

 

[gungate]

No. They are considerably different. You need an AR10 lower for an AR10 upper.

OK cool. So just about every other caliber you can get for a standard AR-15 lower but .308 needs specialized lower and upper it looks like. I really want to build a long-distance shooter so I'll research more. Thanks!

 

[gungate]

Yep, there are two different styles of AR-10 lowers/uppers. I answered this a long time ago regarding the differences, but I cannot remember what thread that was in.

The original Armalite AR-10 lower/upper is different than the LR-308 type lower.

Here is a good write up:

DPMS vs Armalite: AR 10 & LR 308 Pattern Differences

Do you know the difference between the DPMS Gen 1 LR 308 and Armalite AR 10 platform patterns? Before creating your next AR build, read our complete guide!

www.80percentarms.com

All of mine are LR-308 lowers.

So LR-308 is the way to go. I will research them. Do complete rifles tend to be the same cost as building them myself?

 

[DutchV]

Get on the Aero mailing list. They'll run a sale every couple months, or maybe have a batch of so-called blems at a good price.

 

[ted76]

I also recommend getting an AERO lower receiver, the color should be a good match and will fit perfectly. I have two M5 builds with AERO uppers and lowers, one in.308 and the other in .243.

 

[Johnny5k]

If you like Lucas this is a good watch.

 

[jcutonilli]

OK cool. So just about every other caliber you can get for a standard AR-15 lower but .308 needs specialized lower and upper it looks like. I really want to build a long-distance shooter so I'll research more. Thanks!

The issue is really cartridge length and whether you want the cartridge to feed through the mag well. .308 does not feed through an AR15 mag well so there is a different lower that accommodates that cartridge length through the mag well. You may be able to find longer cartridge uppers that attach to an AR15, but they do not feed through the mag well. I have seen them for 50BMG. It is possible that someone else makes other caliber uppers that do not feed through the mag well, but you are kind of defeating the purpose of using an AR15 lower.

 

[Johnny5k]

The issue is really cartridge length and whether you want the cartridge to feed through the mag well. .308 does not feed through an AR15 mag well so there is a different lower that accommodates that cartridge length through the mag well. You may be able to find longer cartridge uppers that attach to an AR15, but they do not feed through the mag well. I have seen them for 50BMG. It is possible that someone else makes other caliber uppers that do not feed through the mag well, but you are kind of defeating the purpose of using an AR15 lower.

Some use the mag well as the ejection port. AR57 I believe.

 

[gungate]

The issue is really cartridge length and whether you want the cartridge to feed through the mag well. .308 does not feed through an AR15 mag well so there is a different lower that accommodates that cartridge length through the mag well. You may be able to find longer cartridge uppers that attach to an AR15, but they do not feed through the mag well. I have seen them for 50BMG. It is possible that someone else makes other caliber uppers that do not feed through the mag well, but you are kind of defeating the purpose of using an AR15 lower.

Thank you! - That is the best reason yet for why an AR-15 lower can't do .308. The bullets don't fit!

 

[gungate]

I am budgeting $1500 for 2023 for new firearms. I haven't gotten anything new in a long time. So the question is, should I get a Kriss Vector (or H&K USC) or an AR-10? Hard decision! I would use the carbine more and ammo is cheaper. But, the only long range I really have is an old Remington 700 in 30-06. But I never use that at all and suspect I would rarely use an AR-10.

 

[Art3]

I am budgeting $1500 for 2023 for new firearms. I haven't gotten anything new in a long time. So the question is, should I get a Kriss Vector (or H&K USC) or an AR-10? Hard decision! I would use the carbine more and ammo is cheaper. But, the only long range I really have is an old Remington 700 in 30-06. But I never use that at all and suspect I would rarely use an AR-10.

The AR10 could easily suck up that budget...and more (especially if you put decent glass on it). The parts are not all the same Lego-like spec as 15 either, so you have to be a little more careful about building.

I found that, once it was in stock, the fully assembled Aero upper I wanted was a good bit cheaper as a whole than piecing it together.

 

[gungate]

The AR10 could easily suck up that budget...and more (especially if you put decent glass on it). The parts are not all the same Lego-like spec as 15 either, so you have to be a little more careful about building.

I found that, once it was in stock, the fully assembled Aero upper I wanted was a good bit cheaper as a whole than piecing it together.

Good call. I was thinking $1.1kish for the gun and $400ish for the optics. I do have a decent Vortex that I could put in it. It currently is on an air-gun so really being wasted at the moment. I guess I could also maybe swap or sell one of my 5 or 6 (or so) AR-15s that also don't get used and get an AR-10 instead.

 

[DaemonAssassin]

Good call. I was thinking $1.1kish for the gun and $400ish for the optics. I do have a decent Vortex that I could put in it. It currently is on an air-gun so really being wasted at the moment. I guess I could also maybe swap or sell one of my 5 or 6 (or so) AR-15s that also don't get used and get an AR-10 instead.

Build the AR-10 from a Aero lower and Aero upper. Come to the dark side, we have milk, cookies, and bacon.

 

[Russ D]

There are cartridges out now that can get closer to .308 ballistics and still fit in an AR15 lower. That could give you more $ for glass if you are only buying an Upper.

 

[slsc98]

Someone (I believe it was here on MDS) posted THE MOST informative (incredible, really) chart on 7.62/308 uppers and lowers - I saved it regretting a bit the only credit I’d be able to give sharing it forward was that members forum “handle” … and now I can’t seem to find it … but, I’ll keep looking.

ETA: Found It!!!!!