458 SoCom AR

[Hoss50]

Has anyone built one? My son has a dream of a big bore AR. What are the things I need to know if any?

 

[Darryle]

I like the 458, love the 375

Built the 458, 375 and 358. If I was going to build one again, it would be the 375. Unless he plans on running heavy subsonics, the 375 will do everything he'd want.

Go over to the 458 Socom forums, those guys have a ton of information on every variant, every know issue and every known solution.

There are barrels to avoid, the biggest issue is that some manufacturers completely remove the 6 O-clock lug in the barrel extension creating one wide smooth ramp, that puts more stress on the remaining lugs.

It's not a cheap to run chambering, be prepared for deep empty pockets.

It's a great choice for quite a few scenarios, unless you have the poors like me

 

[Dave in WI]

Save yourself some grief and work directly with Tony Rumore.
Tromix

 

[bschneiderheinze]

I have an upper for sale Rock River factory 14.5" barrel with pinned brake

 

[Wolf76]

Why not a 450bm? Seems much easier

 

[crazymonkey]

Looked at building one and way to much stuff to watch for . You've got barrel issues with feed ramp and gas port. Issues with bolt and carrier from opening the face to accept the case . They run thin and stress the locking lugs. Then you get into the buffer system to keep it all running. After all that I'd look at Tromix if you go that way . I went into a ar10 in 308 for my heavy work. And I'm in the middle of a 300 blk build for hogs running subs and a can.

 

[HRM Johnny]

Tag

 

[Mike D Texas]

Yes I've had one for years and have none of the internet lore problems mentioned here. Buy good parts from reputable people and you'll be good.

Tri mix is probably the best resource out there for parts and information.

 

[ARlife4me]

Make sure it's a "big bore" upper receiver or the case/brass will NOT eject! Standard ejection ports are NOT large enough for the brass.

 

[Mike D Texas]

Make sure it's a "big bore" upper receiver or the case/brass will NOT eject! Standard ejection ports are NOT large enough for the brass.

My VLTOR upper has a large enough ejection port but yes a lot of them don't.

Tromix has the large port ones.

 

[cohunt]

Why not a 450bm? Seems much easier

This is what I did.

Looked Into all the big bores including 50 beo, settled on the 450bm for cost, ammo,brass, bullet availability, and least possible operating issues.

 

[Morrison]

Has anyone built one? My son has a dream of a big bore AR. What are the things I need to know if any?

I chose the 450 Bushmaster over the Socom because of the hunting regulations that require straight walled cartridges. My only suggestion would be to use an adjustable gas block and a brake to prevent damage to the lower.

 

[Hoss50]

I don't think he is dead set on 458 socom, so maybe we will look more at Bushmaster too.

I had heard 450 bushmaster was hard on magazines vs socom.

 

[Varmint Hunter]

There is a better selection of bullets for the SOCOM, IMO. I just slapped a RRA complete upper on my lower and have never had a problem.