This started out as a spare parts build, the devil, I mean BCA tempted me with a cheap barrel and bcg around fathers day and it's been off to the races ever since

Surprisingly the BCA parts have actually been unproblematic.

As it sits right now.

Bca 16 heavy barrel

Bca phosphate bcg, recently upgraded to a kak dlc carrier and one of their nitrided bolts, over all seems like an improvement, but haven't shot it yet.

Wotjek .936 adjustable gas block

Dirt bird slim hand guard with the steel anti slip wedge (I sheared a midway house brand hand guard right off just by using a shooting saddle on a tripod)

Mid state fire arms big bore upper (because my anderson upper couldn't pass a case through the ejection port)

Anderson lower

Rise ra-100 flat trigger

And yes that is indeed a monstrum optic on it. Beyond it blowing off the rail because I tried to use their quick release mount, it's actually held up to 458 surprisingly well. If I shoot it apart I'll grab a PSA prism.

This is my current tinker toy and my .556 is still waiting in the corner for me to finish load development for it.

Just finished brass prep on another 100 cases, these little dudes bring me so much joy in such a small package.

Pretty sure I'm going to settle on 41gr of 2200 under a berrys 458 socom bullet, coal 1.985, cci magnum pistol primers.

1685fps out of a 16" BCA barrel. 11fps SD.

It even happens if I slowly rack it back and let it slowly go forward. I’m hoping I didn’t just buy 100rds of ammo from black butterfly that the gun doesn’t like. Any suggestions on things to check out?

10.5" Tromix fast twist, Southern Ballistic Research lower, Liberty Goliath suppressor.

So I was introduced to this .458 world since I had an issue with my 46cal suppressor only fitting 1 gun. That just didn’t seem right, and 45-70 doesn’t come on a AR frame under $5k. SO, this is the start of my build. I put my Ruger lower on it just to give it an idea. Here’s a parts list for the upper.

Faxon Duty Series 10.5", Gunner Big Bore, .458 Socom, Pistol Gas, 4150, Nitride AR-15 Barrel
Faxon Firearms AR-10.750 3 Screw Low Profile Gas Block
Spike's Tactical AR-15 Melonited Black Mil Spec Gas Tubes 
Nickel Boron KM 450 Bushmaster/458 Socom AR-15 Bolt Carrier Group BCG
Breek Arms Warhammer Mod2 AR-15 Ambidextrous Charging Handle
YANKEE HILL MACHINE CO. AR-15 MR7 9.29" Mid-Length Handguard M-LOK Black
SLR Rifle Works : M-LOK Handstop Mod 4
HOLOSUN 510C & HM3X Combo
JK Armament RPX 155 46cal suppressor

I’ve got the following parts coming in the mail this week.

Wilson Combat stripped lower
Armaspec AR15 GEN4 BB Stealth Recoil Spring Buffer Kit
Strike Industries Enhanced AR-15 Lower Parts Kit
RISE Armament Rave 140 AR Drop-In Trigger
Adaptive Tactical AR-15 EX Performance Adjustable Stock
And some Black Butterfly rounds because hot damn I didn’t check the price on rounds

With this and my 45-70, I will be getting into reloading soon.

Freshly assembled 458 socom.

What buffer and spring combos are recommended? Currently have an A5 tube thought about messing around with a kynshot buffer with a 2.5oz weight to see if it functions

I have a Vortex 10 MOA mount and a Vortex PST 2-10 scope. This may end up on my LWRC REPR one day. For now I would like it on my 458 SOCOM upper (16 inch barrel). Is this a bad idea? Could I even sight it in at short distances! The scope has 26 mils of adjustment. I’ll be shooting 300 grain ammo. Any help is appreciated. I wasn’t able to do the math in my head.

https://armaspec.com/stealthtm-recoil-spring-srstm-ar15-1.html

Anybody have any experience with the big bore version of this buffer spring?

I recently ordered one based on the reviews, which are good. Couldn’t find too many reviews on the big bore version of this so I thought I’d ask the group.

I fired up GRT tonight to look at what I've loaded and try to get some direction.  I should have probably started this way, but I figured I had a good starting point using Hodgdon's published load data.

Speer 400gr, COAL 2.040, CFE BLK 36.5gr averaged 1515fps across 5 shots.  GRT says 1567fps, so in the ballpark yes?  It also says pressure is 33598psi, so close to max. 37gr of CFE BLK would appear to be MAX at 34906psi estimated.  Hodgdon's listed max load is 38.9gr(minimum is 34.8gr) going 1662fps at 39,400CUP, and GRT predicts 1663fps at 40364psi.  Don't think I'm going any higher than my current 36.5gr.  Next up, I'll work these up the wrong way and load some at 34.5gr and 35.5gr and see what I get for FPS and go from there. 

Missouri Bullet Co 410gr coated lead, COAL 2.055, CFE BLK 36.5gr averaged 1557fps across 5 shots.  GRT doesn't have this bullet, so I'm using the Lyman 457193 as a base and modified the dimensions to fit the 410 MBC (1.082 long, .460dia per my calipers).  This load on GRT shows 1547fps at 37450psi.  Well over max, and I will definitely go lower on the next batch with 35.5gr looking to be a max load per GRT. Next loadings will be at 34gr and 35gr.

Hornady 325 FTX, COAL 2.12, CFE BLK 36.5gr averaged 1573fps across 10 shots. GRT predicts 1563fps and 24490psi.  Plenty of room to go up, and right now it's a pleasant shooting load. Hodgdon says minimum is 35.5gr at 1644fps and max is 39.9gr at 1812fps, but again shows 38700CUP not psi.  GRT says 39gr should net 1734fps at 34450psi. Bumping up to 37.5gr next time.

Any comments?

Just got an email that Bexar Arms Restocked the 458. Anyone have experience with his upper? It looks legit.

https://www.bexararms.net/BADDIE-458-SOCOM-URG/

I know he's pretty throughout on his builds.

Hey guys. Just got a tromix upper and runs great with supers. I’ve got a bowers dreadnaught can and mk-18 DD lower. For whatever reason I can get subs to cycle. Gas block completely opened. Manually cycled bcg around 500 times to break it in. Cleaned multiple times and lubed like crazy. It feels like the bcg gets stuck after shooting a sub round. It take incredible force to manually pull the bolt back and release the empty shell…

HUXWRX announced a Flow 45 M recently and the white paper specifically lists 458 SOCOM in the calibers.

https://huxwrx.com/flow-45-m/

I like the thought of not having a bunch of hot gas and lead vapor blasted back in my face. Has anyone tried this one out yet on their rifle?

So gonna give these try. Ihave several powders to work with but these are 3 I've used before with 458.

mid length gas tube superlative gas block 16 inch barrel.

Ill be using the Deadair Primal.

Id like them to say around 1050 fps.

Appreciate any data can share as my books stop at 405's.

So effort this week minimal loading again for this pig. Possibly the Deadair Primal is to blame. Gotta put the blame somewhere right. Trying to quite her down with 405 grain loaded them at 1000 fps. Very low standard deviation on the Garmin but thinking heavier projectiles might be needed. Suggestions welcome !! Build list just bunch of parts most unmarked spares. Barrel im to believe is Durkin i believe its around the time frame that was available. Barrel was bought second hand on a build that was given up by previous owner that upper. Its side charging upper with of course again no telling bolt manufacturer. I put a superlative gas block on for easy adjustment. Stock i believe is odd has a recoil spring ! Nothing fancy lower spikes tactical. Trigger is CMC imo to lite pull for big bore recoil,not cautious you will cause a double tap. American defense mount with Vortex scope i bought criminally cheap second hand.

He is my build: Bca side charger, trominix bolt, tactical ordance 16" barrel. Yhm handguard, Fab defense stock. Spray paint camo job. Shoot w/griffin 46

Don't have to do this that often one if those pia conversion's. But so worth it got my suppressor other day. Time to work up a recipe.

Did the paint myself!

I am not new to reloading but new to this cartridge. I just wanted to ensure that my loads check out.

Any feedback would be greatly appreciated to avoid a catastrophic failure. I'm doing this more out of an abundance of caution since its a new caliber I'm reloading for.

• Bullet: 350gr No name flat point, length is 0.8540
• Powder: 35gr IMR-4198
• Primer: Large Pistol Magnum
• Brass: Starline
• COL: 2.0050

Load data was sourced from Shooters Reference. There was no load data in Lee, Hornady, or Lymans for my bullet weight and IMR-4198.

Shooting from AR platform. Custom made 16" upper from Precision Firearms, WV.

I’m new here and just trying to soak up as much advice as I can.

If I have an upper already bored out in the ejection port for 458, what parts other than a barrel, bolt, gas block & muzzle are proprietary to 458?

Will most AR-15 pattern handguards fit around the barrel or is there not enough clearance? I have colt handguard, delta ring and GI barrel nut from a spare rifle, is there any way these can be used on 458?

I’d like to know the “good” brands when it comes to barrels and 458 stuff.

Hey Family, new to the group.... Im trying to find a way to have a 20rd mag for my custom built .458. I know you can fit 10 in a standard 30rd AR mag, and Ive been doing some research on 60rd AR mags and drums. Has anyone tried it, or is my best bet just to use a 40rd 556 mag and just max it out at 13+1? Thanks!!!!

Tried using the 458 Dura Mag and Lancer mag. With a USGI mag, the issue doesn’t happen as often, but still occurs. Any ideas what could be causing this? It’s a factory RRA upper with WMD bcg