Best AR Lower for .458 SOCOM + .223 Rem + .300 BO + .22LR Conv.

[Mike1234567]

I want to purchase an AR in .458 SOCOM plus a .223/5.56 Wylde upper plus .300 BO barrel plus a .22LR conversion. For now... I want to share the lower for all.

I know the .458 SOCOM requires a sturdy lower. Which ones are strongest without being overpriced?

I know many people don't like the .22LR conversions but I want to save some cash... but want reliability too. Also, this is primarily to shoot Aguila SSS so I need a faster twist rifling than typical .22LR barrels have... any 1:9 or faster twist AR barrel will be fine.

Are there any uppers that will make barrel change between .223/5.56 and .300 BO faster/easier?

I prefer stainless steel. I prefer 1:8 twist for the .223 so I have no worries at all shooting 75gr bullets.

Any other advice?

 

[wally]

Are there any uppers that will make barrel change between .223/5.56 and .300 BO faster/easier?

You have to remove the gas tube and or gas block to remove the barrel nut, I don't think they were really designed for swapping barrels out "often".

There are some "take down" AR uppers that might be adaptable to other barrels, but I've no experience with them other than seeing them at gun shows.

There are other "high end" ARs designed for fast barrel swaps but the special barrels seem limited in selection and in short supply.

I've not had the greatest luck with feeding reliability of the Aquila SSS in autoloaders.

 

[Ken70]

Get one of the $79 lowers floating around. Spending 3x isn't going to get you anything better; stronger. Only a billet that is cut to some oversize pattern is going to be stronger.

 

[sixgunner455]

I'd get the .223/5.56 first, then your .22 conversion kit. Then build the .458 upper. Then you can decide if you really need the .300 BO. What it can do that you won't have covered by then, I have no idea, but if you need/want it still, you could build a dedicated upper for it.

 

[Telekinesis]

A standard lower should be fine. I probably wouldn't go with a polymer lower though.

I would strongly recommend that you get separate uppers for the 5.56 and .300 Blk barrels. While the barrel is technically the only thing that will need to be changed, actually changing it requires you to disassemble the entire upper. Then once you get everything swapped, you'll still have to adjust your sights to the new barrel as it will likely have a different POI/POA.

Then you can decide if you really need the .300 BO. What it can do that you won't have covered by then, I have no idea, but if you need/want it still, you could build a dedicated upper for it.

.300 Blk makes a great caliber for a SBR because it doesn't loose much velocity dropping from a 16" barrel to a 10" barrel. It is also an excellent round to suppress if you are using subs. And, if you plan it right, you can wind up with a barrel/suppressor combo that still makes the gun shorter than a standar 16" barreled carbine.

 

[Mike1234567]

I'm paying attention... just waiting for more input.

 

[zoom6zoom]

As an armorer, I would also recommend a separate upper; you don't want to be having to swap barrels, you're not going to be doing that at the range. Can't get any faster changeover than pulling two pins. An upper will be cheaper than the aggravation and time needed to rebarrel over and over.

 

[ugaarguy]

I toyed with the changeable bbl idea. It doesn't make sense from the problems with sighting, the expense of the upper, and the expense of the bbls. It's much easier to just get separate standard uppers.

Any good forged aluminum lower will work. Get a mil-spec buffer tube for max strength in that area. The upper and the buffer tube assembly are going to take far more abuse than rest of the lower.

 

[gunnutery]

They make .50bmg bol action uppers that fit onto standard AR lowers, so you'd be fine with a no-name metal lower for .458.

 

[eldon519]

Just start with a Colt 6920 or 6720 complete rifle if you want a 5.56mm. They are mil-spec quality vs so many of the common AR names like DPMS, Bushmaster, Olympic Arms, etc. It's basically an actual military grade M4 with 2" added to the muzzle, and semiauto-only of course. Pretty much the gold standard and excellent bang for your buck if you are concerned with quality.

 

[.338-06]

Mike, here's some off-topic advise. If you are going to get a .458 Socom start looking for ammo/brass NOW. I just got a .458 upper and can't find a single piece of ammo in my state (AK).

 

[jmorris]

If you do a 458 upper you don't have a bunch of choices. The upper will be a little different than what other rounds will work with. For a lower, I have shot many round through mine in a few different lowers including a "plastic" cav arms, all work fine.

 

[Onewolf]

I agree with the others. Separate uppers would definitely be the way to go. And then once you have all the uppers you can get new lowers and have MORE GUNS. More guns > Less guns.

 

[Mike1234567]

Okay... my suspicions are confirmed regarding the 300 BO barrel. It's better to buy a complete upper. I thought I'd read about some uppers that had "quick-change" barrels but those are not yet prime-time. So, for now, I'll forgo the 300 BO.

I've read several threads in which a "standard" lower wasn't strong enough to handle the .458 SOCOM beast. It's good to know that an average lower can handle the task.

I agree that buying a complete .223Rem/5.56 rifle, to start, is the way to go.

I can add a .458 SOCOM upper later. Any advice? I've heard the RRA have had some issues lately.

RE .458 SOCOM brass and ammo availability: I'm aware this has always been a problem. I know I need to work around that. BTW, if I DO get into .458 SOCOM that will be the straw that broke the camel's back regarding me getting into reloading!!

RE .458 SBR: I'll probably get into that along with a sound suppressor. But the TWO tax stamps REALLY pee me off.

RE shooting Aguila SSS: I've read mixed reviews. I suspect I may need to tweak/tune a conversion kit to function well. Provided said tweak-ability can be done... I'm okay with that.